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  • 42.75
  • Fluid Mechanics and Thermodynamics
  • 1995-1999  (441)
  • 1950-1954  (30)
  • 1
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    Notes on Menippus and Issikia from Sumatra and Java, Indonesia (Coleoptera: Chrysomelidae: Galerucinae) (1999)
    In:  Zoologische Mededelingen (00240672) vol.73, 1-11 (1999) p.187
    Details
    Publication Date: 2007-01-23
    Description: Menippus philippinensis Jacoby, 1894, is reported from Java, and Issikia clarki (Jacoby, 1884) comb. nov., from Sumatra.
    Keywords: Coleoptera ; Chrysomelidae ; Galerucinae ; Menippus ; Issikia ; Issikia clarki ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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  • 2
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    Galeruca malakkana spec. nov. from Malaysia (Coleoptera: Chrysomelidae: Galerucinae) (1998)
    In:  Zoologische Mededelingen (00240672) vol.72, 1-10 (1998) p.101
    Details
    Publication Date: 2007-01-26
    Description: Galeruca malakkana spec. nov., a new species is described from Malaysia.
    Keywords: Coleoptera ; Chrysomelidae ; Galerucinae ; Galeruca ; new species ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 3
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    Nieuwe en oude vindplaatsen van de roofvlieg Machimus cowini in Nederland (Diptera: Asilidae) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.143
    Details
    Publication Date: 2007-01-10
    Description: New and old records of the robberfly Machimus cowini in the Netherlands (Diptera: Asilidae) Until recently, Machimus cowini (Hobby, 1943) was known from just one record in the Netherlands. An examination of Dutch specimens of the similar M. cingulatus revealed specimens of M. cowini from five new localities. The records are concentrated on the island Ameland and along the rivers Waal and Maas. On Ameland, M. cowini probably occurs in coastal dunes. Near Nijmegen the species was found in grassy vegetation on floodplains and on riverdunes near the river.
    Keywords: Insecta ; Diptera ; Asilidae ; Machimus cowini ; Nederland ; Verspreiding ; Biotopen ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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  • 4
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    The Palaearctic species of the genus Diachasmimorpha Viereck (Hymenoptera: Braconidae: Opiinae) (1999)
    In:  Zoologische Mededelingen (00240672) vol.73, 1-11 (1999) p.1
    Details
    Publication Date: 2007-01-23
    Description: Two new species of the genus Diachasmimorpha Viereck, 1913 (Braconidae: Opiinae) are described: D. feijeni spec. nov. from Bhutan (reared from Bactrocera minax (Enderlein) (Diptera: Tephritidae) in fruits of Citrus reticulata Blanco (mandarin)) and D. budrysi spec. nov. from Far East Russia. A key to the Palaearctic species is added, including two similar species (Fopius alternatae (Tobias, 1977), and F. myolejae (Tobias, 1977)).
    Keywords: Hymenoptera ; Braconidae ; Opiinae ; Diachasmimorpha ; Palaearctic ; Bhutan ; Russia ; key ; Diptera ; Citrus reticulata ; Bactrocera minax ; Tephritidae ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 5
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    Bobekoides gen. nov. (Hymenoptera: Braconidae: Alysiinae) from South Africa (1998)
    In:  Zoologische Mededelingen (00240672) vol.72, 1-10 (1998) p.105
    Details
    Publication Date: 2007-01-23
    Description: A new genus of the subfamily Alysiinae (Braconidae) is reported from South Africa (Bobekoides gen. nov.; type species: Bobekoides fulvus spec. nov.), illustrated, and described. A key to the species is added. The new genus is closely related to the East Palaearctic genus Hylcalosia Fischer, 1967.
    Keywords: Hymenoptera ; Braconidae ; Alysiinae ; Alysiini ; Bobekoides ; Afrotropical ; South Africa ; key ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 6
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    Synopsis of the Neotropical genus Rhodopygia Kirby, 1889 (Odonata: Libellulidae) (1998)
    In:  Zoologische Mededelingen (00240672) vol.72, 1-10 (1998) p.1
    Details
    Publication Date: 2007-01-23
    Description: A synopsis of the genus Rhodopygia Kirby is given. Its species are discussed and their diagnostic morphological characters elucidated by figures. The hitherto unknown females of R. hinei Calvert and R. pruinosa Buchholz are described. A key to the species is provided.
    Keywords: Libellulidae ; Rhodopygia ; Central and South America ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 7
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    Phaenocarpa helophilae spec. nov. (Hymenoptera: Braconidae), a gregarious parasitoid of Helophilus larvae (Diptera: Syrphidae), with notes on related species (1998)
    In:  Zoologische Mededelingen (00240672) vol.72, 1-10 (1998) p.15
    Details
    Publication Date: 2007-01-23
    Description: For the first time a gregarious parasitoid belonging to the genus Phaenocarpa Foerster, 1862 (Braconidae: Alysiinae) is reported, and described as P. helophilae spec. nov. from England. The first record of Chloropidae as host for a Phaenocarpa species is given; P. livida (Haliday, 1838) reared from Calamoncosis (Rhaphiopyga) glyceriae Nartshuk, 1958. Sathra debilis Foerster, 1862, is synonymised with P. livida (Haliday). Additionally, Phaenocarpa curticauda spec. nov. from The Netherlands is described and fully illustrated. A lectotype is designated for Alysia pectoralis Zetterstedt, 1838, and Phaenocarpa rufoflava Papp, 1968, is recognised as a valid species.
    Keywords: Hymenoptera ; Braconidae ; Alysiinae ; Alysiini ; Phaenocarpa ; Diptera ; Syrphidae ; Chloropidae ; Helophilus ; Calamoncosis ; Europe ; Palaearctic ; distribution ; biology ; gregarious ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 8
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    Pemphredon montana, een nieuwe graafwesp voor Nederland (Hymenoptera: Specidae) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.142
    Details
    Publication Date: 2007-01-10
    Description: Pemphredon montana, new to The Netherlands (Hymenoptera: Sphecidae) In 1998 Pemphredon montana Dahlbom, 1845 was recorded for the first time in the Netherlands. The species was found nesting in the insulating material of a caravan in the northernmost part of the province of Overijssel.
    Keywords: Insecta ; Hymenoptera ; Sphecidae ; Crabronidae ; Pemphredon montana ; Nederland ; Verspreiding ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 9
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    Porcellium conspersum, een in Nederland zeer zeldzame landpissebed van vochtige bossen (Crustacea: Isopoda: Oniscoidea) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.140
    Details
    Publication Date: 2007-01-10
    Description: The influence of recent inundations on the distribution pattern of the isopod Eluma purpurascens in the province of Zeeland (Crustacea: Isopoda: Oniscoidea) Small scale mapping of Eluma purpurascens Budde-Lund, 1885 in the province of Zeeland revealed a remarkable distribution pattern. The species proved to be absent in parts which have been inundated during and after the second world war. This study shows that for the interpretation of distribution patterns the history of the study area should be considered.
    Keywords: Arthropoda ; Crustacea ; Isopoda ; Oniscoidea ; Nederland ; Verspreiding ; Biotopen ; Herkenning ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 10
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    Faunistiek en ecologie van het zweefvliegengenus Epistrophe in Nederland (Diptera: Syrphidae) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.33
    Details
    Publication Date: 2007-01-09
    Description: Faunistics and ecology of the syrphid genus Epistrophe in The Netherlands (Diptera: Syrphidae) Ten species of Epistrophe have been found in the Netherlands, two of which, E. cryptica and E. similis, are recorded here for the first time. The distribution, changes in distribution and ecology of the species were investigated and are illustrated by distribution maps and diagrams of the flight period. In all species, except E. eligans, females were observed more than males. Furthermore, females seem to be active later in the season than males. It is discussed that this is probably caused by the differences in behaviour between the males of the species.
    Keywords: Insecta ; Diptera ; Syrphidae ; Epistrophe ; Fenologie ; Verspreiding ; Biologie ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 11
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    De sneeuwspringer Boreus hyemalis in Nederland (Mecoptera: Boreidae) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.1
    Details
    Publication Date: 2007-01-26
    Description: Until recently Boreus hyemalis was considered to be a rare species in The Netherlands. It was only known from a few localities in The Netherlands in the provinces of Noord-Holland, Zuid- Holland, Utrecht, Gelderland and Drenthe. The last few years many new populations have been discovered. In this paper the first records for the provinces of Limburg, Noord-Brabant and Overijssel are presented. The species seems to prefer scarcely vegetated patches in sanddunes, dominated by greyhair grass Corynephorus canescens and the moss Polytrichum piliferum. It proved to be relatively easy to find, when the right places were searched in the right period (October until February).
    Keywords: Insecta ; Mecoptera ; Boreidae ; Boreus hyemalis ; Sneeuwspringer ; Verspreiding ; Nederland ; Biotopen ; Biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 12
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    The genus Bryotropha in the Netherlands (Lepidoptera: Gelechiidae) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.79
    Details
    Publication Date: 2007-01-10
    Description: Het genus Bryotropha in Nederland (Lepidoptera: Gelechiidae) Het genus Bryotropha staat bekend als een notoir lastig geslacht van kleine bruine motjes. Die moeilijkheid komt door de variatie, maar vooral ook door gebrek aan bruikbare beschrijvingen. Met dit artikel zijn de negen Nederlandse soorten te determineren. Vanwege het gebrek aan determinatieliteratuur in heel Europa is het in het Engels geschreven. Behalve de maar één keer waargenomen B. domestica, zijn de meeste soorten vrij gewone verschijningen in ons land, zoals uit de kaarten blijkt.
    Keywords: Insecten ; Lepidoptera ; Gelechiidae ; Verspreiding ; Nederland ; Fenologie ; Waardplanten ; Biotopen ; Determinatiesleutel ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 13
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    De valkruidmineervlinder Digitivalva arnicella in Nederland: herontdekking en behoud (Lepidoptera: Plutellidae: Acrolepiinae) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.15
    Details
    Publication Date: 2007-08-06
    Description: The occurrence of Digitivalva arnicella in the Netherlands: rediscovery and conservation (Lepidoptera: Plutellidae: Acrolepiinae) Digitivalva arnicella (Heyden, 1863), previously only known from two localities before 1902, has been rediscovered in eight localities in the northern part of the Netherlands (province of Drenthe) on its host Arnica montana. On the basis of leafmines, found in old herbarium collections, it can be concluded that the species was once widespread within the range of its host in the northern and eastern parts of the Netherlands and has apparently been overlooked by entomologists since. D. arnicella is a much endangered species in the Netherlands, because of the dramatic decline of its host. Two of the eight discovered populations have been lost since their discovery in the first half of the 1990’s. Systematics and life history of the species are described and illustrated, the distribution is mapped and advise for management of its sites are given. The current management of some populations of Arnica, by mowing the site completely in August, is disastrous for the young caterpillars, mining the leaves.
    Keywords: Acrolepiinae ; Plutellidae ; Yponomeutoidea ; Digitivalva ; Netherlands ; conservation ; Arnica ; Digitivalva arnicella ( Plutellidae- ) ; Habitat management ; Endangered status ; effect of food plant shortage ; conservation proposals ; Food plants ; Arnica montana ; effect on decline to endangered status ; Decline-to-endangered-status ; influences-and-conservation ; Netherlands ; Distribution ; population dynamics and conservation ; endangered species ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 14
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    De boskrekel Nemobius sylvestris in de duinen bij Bergen (Noord-Holland) (Orthoptera) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.91-93
    Details
    Publication Date: 2007-01-09
    Description: Nemobius sylvestris in the dunes near Bergen (Orthoptera) A large population of Nemobius sylvestris (Bosc, 1792) has been found in the dunes near Bergen (Noord-Holland), 60 km northwest of the nearest known site in the Gooi-area. This discovery sheds new light on a specimen from Bergen found in a collection, which was thought to be mislabelled.
    Keywords: Insecta ; Orthoptera ; Gryllidae ; Nemobius sylvestris ; Nederland ; Verspreiding ; Biotopen ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 15
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    Interessante libellenwaarnemingen in 1998 (Odonata) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.85
    Details
    Publication Date: 2007-01-09
    Description: Interesting new records of Odonata in the Netherlands in 1998 A survey of the most interesting observations on Dutch Odonata is presented. During the Odonata Recording Scheme many new records of rare species have become available. Gomphus flavipes, G. vulgatissimus, Anax parthenope, Sympetrum pedemontanum and S. depressiusculum seem to become more common. The status of some threatened species is elucidated: Calopteryx virgo, Sympecma paedisca, Coenagrion hastulatum and Cordulegaster boltonii.
    Keywords: Insecta ; Odonata ; Verspreiding ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 16
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    Cladistics and biogeography of the assassin bug genus Rasahus Amyot & Serville (Heteroptera: Reduviidae: Peiratinae) (1998)
    In:  Zoologische Mededelingen (00240672) vol.72, 1-10 (1998) p.73
    Details
    Publication Date: 2007-01-23
    Description: The assassin bug genus Rasahus Amyot & Serville (Heteroptera: Reduviidae: Peiratinae) comprises 26 Neotropical species. A cladistic analysis of the genus was carried out using 63 characters from external morphology, body vestiture, and male and female genitalia, with the species considered as terminal taxa. The analysis yielded 149 equally parsimonious cladograms, each with 206 steps, CI = 0.35, and RI = 0.60; the successive weighting procedure resulted in eight cladograms (CI = 0.79 and RI = 0.91). In the strict consensus cladogram, two major clades are delimited: one comprising the species R. rufiventris, R. hamatus, R. arcitenens, R. arcuiger, R. amapaensis, R. thoracicus, R. biguttatus, R. argentinensis, R. limai, R. grandis, and R. angulatus; and the other with R. castaneus, R. aeneus, R. scutellaris, R. maculipennis, R. brasiliensis, R. sulcicollis, R. surinamensis, R. albomaculatus, R. guttatipennis, R. atratus, R. peruensis, R. costarricensis, R. bifurcatus, R. flavovittatus, and R. paraguayensis. A cladistic biogeographic analysis of the provinces of the Neotropical subregion, considering distributional data of the species of Rasahus and three other genera of Peiratinae (Eidmannia, Melanolestes, and Thymbreus) was carried out. Four general area cladograms were obtained applying programs COMPONENT 2.0 and TASS. The most parsimonious general area cladogram (= implying fewer items of error) was obtained with COMPONENT 2.0 minimizing the number of leaves added, and shows the sequence (Desierto, (Caatinga, (Cerrado, (Chacoan, (Caribbean, Amazonian), (Paranaense, Atlantic))))). This sequence of area relationships is congruent with the history previously hypothesized for the subregion, where the development of an open vegetated diagonal (comprising the Chacoan, Cerrado, and Caatinga provinces) due to the aridification induced by the gradual uplift of the Andes, separated the former Amazonian forest in a northwestern part (Caribbean plus Amazonian provinces) and a southeastern part (Paranaense plus Atlantic provinces).
    Keywords: Cladistics ; biogeography ; Rasahus ; Heteroptera ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 17
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    Revisionary notes on Bentonia van Achterberg, 1992 (Hymenoptera: Braconidae: Orgilinae) with description of two new species (1998)
    In:  Zoologische Mededelingen (00240672) vol.72, 1-10 (1998) p.51
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    Publication Date: 2007-01-26
    Description: Two new species of the genus Bentonia van Achterberg, 1992 (Braconidae: Orgilinae) (B. inca from Peru and B. xochiquetzalis from Mexico) are described and partly illustrated. A third undescribed species was found for which some characters are listed. The distribution of B. scutellaris van Achterberg, 1992, is extended west to Peru and B. longicornis van Achterberg, 1992, north to Venezuela. An identification key is added.
    Keywords: Braconidae ; Orgilinae ; Bentonia ; Peru ; Mexico ; Venezuela ; key ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 18
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    The West Palaearctic species of the subfamily Paxylommatinae (Hymenoptera: Ichneumonidae), with special reference to the genus Hybrizon Fallén (1999)
    In:  Zoologische Mededelingen (00240672) vol.73, 1-11 (1999) p.11
    Details
    Publication Date: 2007-01-23
    Description: The West Palaearctic species of the subfamily Paxylommatinae are reviewed and the species of the genus Hybrizon Fallén, 1813, from the Palaearctic region are keyed. Hybrizon juncoi (Ceballos, 1957) is recognized as a valid species, a neotype is designated for Hybrizon latebricola Nees, 1834, and a lectotype is designated for Plancus apicalis Curtis, 1833. Paxylomma grandis Rudow, 1883, Ogkosoma schwarzi Haupt, 1913, and Eurypterna arakawae Matsumura, 1918, are new junior synonyms of Eurypterna cremieri (de Romand, 1838).
    Keywords: Ichneumonidae ; Paxylommatinae ; Hybrizon ; Ghilaromma ; Eurypterna ; keys ; distribution ; Palaearctic ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 19
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    The genus Scrobipalpa in the Netherlands (Lepidoptera: Gelechiidae) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.29
    Details
    Publication Date: 2007-01-10
    Description: Het genus Scrobipalpa in Nederland (Lepidoptera: Gelechiidae) Scrobipalpa is een geslacht van kleine, lastig uit elkaar te houden motjes. In heel Europa zijn ongeveer 70 soorten bekend. Doorgaans zijn de vleugels bruin- of grijsachtig met een tekening van stippels en strepen die bovendien erg kan variëren. Hierdoor kunnen de individuele soorten vaak moeilijk herkend worden. Aan de hand van de genitaliën kunnen soorten wel allemaal gedetermineerd worden. Omdat de literatuur over deze groep niet erg toegankelijk is en bestaande beschrijvingen soms erg onvolledig zijn, wordt dit artikel in het Engels geschreven. Met dit artikel zijn de elf Nederlandse soorten te determineren. De meeste hiervan zijn min of meer gebonden aan de kust. Van alle soorten worden naast beschrijvingen van de vleugeltekening en de genitaliën, ook de verspreiding, de biologie en de ecologie gegeven.
    Keywords: Insecta ; Lepidoptera ; Scrobipalpa ; Verspreiding ; Biotopen ; Fenologie ; Herkenning ; Determinatiesleutel ; Waardplanten ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 20
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    Cheilosia caerulescens in Nederland in 1998 (Diptera: Syprhidae) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.93
    Details
    Publication Date: 2007-01-09
    Description: New records of Cheilosia caerulescens in the Netherlands (Diptera: Syrphidae) Cheilosia caerulescens is a rare hoverfly in The Netherlands. Until 1998 only four records were known, the first in 1986. In 1998 the species was found on three new and one old locality. The record from Heemstede (province of Noord-Holland) is among the northernmost in the European distribution of this species. Three of the four records originate from gardens.
    Keywords: Insecta ; Diptera ; Syrphidae ; Cheilosia caerulescens ; Nederland ; Verspreiding ; Biotopen ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 21
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    Dansmuggen in natuurontwikkelingsgebieden (Chironomidae) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.89
    Details
    Publication Date: 2007-01-09
    Description: Chironomidae in newly created nature reserves In a newly created nature reserve near Eindhoven many interesting species of Chironomidae were found. Several new species to the Dutch fauna were identified and one species (of the genus Neozavrelia) proved to be new to science. The fauna of these young habitats is poorly known, but proves to be very interesting.
    Keywords: Insecta ; Chironomidae ; Verspreiding ; Biotopen ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 22
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    Four new species of Pteromalus Swederus (Hymenoptera: Chalcidoidea: Pteromalidae) and redescriptions of three other species (1999)
    In:  Zoologische Mededelingen (00240672) vol.73, 1-11 (1999) p.165
    Details
    Publication Date: 2007-01-23
    Description: A key to the European species of the Pteromalus altus group is presented. The relationship between this group and species of the genus Euphorbia (Euphorbiaceae) is confirmed. One new species: P. villosae, associated with Euphorbia villosa Waldst. & Kit.is presented. Two new species of the albipennis group: Pteromalus almeriensis and P. costulata are presented. In addition one species of the P. vibulenus group: P. tethys is added. Information on P. sylveni Hedqvist, P. osmiae Hedqvist and P. discors Graham is given.
    Keywords: Chalcidoidea ; Pteromalidae ; Pteromalus ; new species ; redescriptions ; Spain ; Portugal ; France ; Greece ; Euphorbia ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 23
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    The Egyptian species of Encarsia (Hymenoptera: Aphelinidae): a preliminary review (1999)
    In:  Zoologische Mededelingen (00240672) vol.73, 1-10 (1999) p.131
    Details
    Publication Date: 2007-01-23
    Description: The species of Encarsia Foerster (Hymenoptera: Aphelinidae) known from Egypt are revised. A total of 14 species are treated, including one new species. E. indifferentis Mercet, 1929, is synonymised with E. inaron (Walker, 1839). All species are fully described or diagnosed, and illustrated. Host records, and species-distributions outside Egypt, are given.
    Keywords: Egypt ; Encarsia ; Aleyrodidae ; Aphelinidae ; Diaspididae ; parasitoids ; biological control ; natural enemies ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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    Bijzondere kevervondsten in Nederland (Coleoptera: Staphylinidae, Nitidulidae, Dermestidae) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.133
    Details
    Publication Date: 2007-01-10
    Description: Interesting records of beetles in The Netherlands (Coleoptera: Staphylinidae, Nitidulidae, Dermestidae) Tachyporus quadriscopulatus Pandellé, 1869 has been recorded for the second time in the Netherlands at Arcen and Velden, province of Limburg. After 27 years, a third record of Carpophilus marginellus Motschulsky, 1858 can be reported from St. Geertruid, in the southern part of the province of Limburg. One specimen was found outdoors, in a wood. One specimen of Anthrenocerus australis Hope, 1843 was also found outdoors, in Oost- Maarland also in southern Limburg, sitting on a flower in a meadow.
    Keywords: Insecta ; Coleoptera ; Staphylinidae ; Nitidulidae ; Dermestidae ; Nederland ; Verspreiding ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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    Dagvlinders in 1998: nog steeds onder druk (Lepidoptera: Rhopalocera) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.127
    Details
    Publication Date: 2007-01-10
    Description: Butterflies in the Netherlands still under pressure (Lepidoptera: Rhopalocera) New information on the Dutch Rhopalocera fauna since the distribution atlas of Tax (1989) is presented. Coenonympha pamphilus was common in large parts of the Netherlands, but has declined dramatically. C. arcania is now formally extinct in our country. An extensive research showed that Maculinea alcon ericae has dissappeared from many sites. Furthermore the smallest of the two remaining populations of Heteropterus morpheus seems to have gone extinct. On the other hand, Callophrys rubi, has colonized new territory. Lampidus boeticus, was observed once as an adult and once a caterpillar was found between snow peas from Egypt. Colias croceus was very abundant in 1998. The reintroductions of Maculinea teleius and M. nausithous in 1990 appear to have been successful.
    Keywords: Insecta ; Lepidoptera ; Rhopalocera ; Verspreiding ; Bedreiging ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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    De edelherthorzel Cephenemyia auribarbis gekweekt (Diptera: Oestridae) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.109
    Details
    Publication Date: 2007-01-10
    Description: The rearing of the botfly Cephenemyia auribarbis (Diptera: Oestridae) After several failures we finally succeeded in rearing botflies Cephenemyia from third-instar larvae. From a red deer shot at 13 March 1998 about one hundred larvae of Cephenemyia auribarbis (Meigen, 1824) were collected. Ten individuals reached the pupal stage. After 22 days, one fullgrown male died in the pupa, and two males emerged and lived for 17 and 18 days respectively. This is one of the few recorded succesful attempts to rear botflies.
    Keywords: Insecta ; Diptera ; Oestridae ; Cephenemyia auribarbis ; Nederland ; Verspreiding ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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    Een nieuwe vondst van het locomotiefje Chorthippus apricarius in Nederland (Orthoptera) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.90
    Details
    Publication Date: 2007-01-09
    Description: A new record of Chorthippus apricarius in the Netherlands (Orthoptera) Chorthippus apricarius is a very rare grasshopper in The Netherlands. Only three, very widely separated sites are known. In 1998 a small new population has been found in a roadside verge, 2 km southwest of the southernmost site in the south of the province of Limburg.
    Keywords: Insecta ; Orthoptera ; Acrididae ; Chorthippus apricarius ; Locomotiefje ; Verspreiding ; Biotopen ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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    Naamlijst van de glanskevers van Nederland en het omliggende gebied (Coleoptera: Nitidulidae & Brachypteridae) (1999)
    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.11
    Details
    Publication Date: 2007-01-09
    Description: Checklist of the Nitidulidae and Brachypteridae (Coleoptera) of the Netherlands and surrounding regions An annotated checklist of the Nitidulidae and Brachypteridae of the Netherlands and surrounding regions is presented, based mainly on literature research. Since the list of Brakman seven new species to the Netherlands have been published. One of these species, Pocadius adustus, is listed here for the first time. Major nomenclatorial changes, published elsewhere, have been implemented. The list contributes to the faunistic work of the European Invertebrate Survey - The Netherlands. A separate list of hostplants of the Nitidulidae and Brachypteridae is presented.
    Keywords: Insecta ; Coleoptera ; Nitidulidae ; Brachypteridae ; Glanskevers ; Verspreiding ; Waardplanten ; Biologie ; Naamlijst ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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    Three-Dimensional Imaging (1999)
    In:  Other Sources
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    Publication Date: 2011-12-09
    Description: This chapter is concerned with three-dimensional imaging of fluid flows. Although relatively young, this field of research has already yielded an enormous range of techniques. These vary widely in cost and complexity, with the cheapest light sheet systems being within the budgets of most laboratories, and the most expensive Magnetic Resonance Imaging systems available to a select few. Taking the view that the most likely systems to be developed are those using light sheets, the authors will relate their knowledge and experience of such systems. Other systems will be described briefly and references provided. Flows are inherently three-dimensional in structure; even those generated around nominally 2-D surface geometry. It is becoming increasingly apparent to scientists and engineers that the three-dimensionalities, both large and small scale, are important in terms of overall flow structure and species, momentum, and energy transport. Furthermore, we are accustomed to seeing the world in three dimensions, so it is natural that we should wish to view, measure and interpret flows in three-dimensions. Unfortunately, 3-D images do not lend themselves to convenient presentation on the printed page, and this task is one of the challenges facing us.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Flow Visualization: Techniques and Examples; Chap. 10; 245-288
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    Forced Transition Techniques on HSCT Configurations (1999)
    In:  CASI
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    Publication Date: 2004-12-03
    Description: The objectives of this effort were to determine (if possible) the best method: 1) for forcing the boundary layer to transition, 2) for assessing trip effectiveness, 3) for quantifying trip drag, 4) for testing at Reynolds numbers per foot from 5 million to maximum available rather than I to 5 million, and 5) for boundary layer state determination.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 477-508; NASA/CP-1999-209691/VOL1/PT1
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    Coherent Pulsed Lidar Sensing of Wake Vortex Position and Strength, Winds and Turbulence in the Terminal Area (1999)
    In:  CASI
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    Publication Date: 2004-12-03
    Description: NASA Langley Research Center (LaRC) has field tested a 2.0 gm, 100 Hertz, pulsed coherent lidar to detect and characterize wake vortices and to measure atmospheric winds and turbulence. The quantification of aircraft wake-vortex hazards is being addressed by the Wake Vortex Lidar (WVL) Project as part of Aircraft Vortex Spacing System (AVOSS), which is under the Reduced Spacing Operations Element of the Terminal Area Productivity (TAP) Program. These hazards currently set the minimum, fixed separation distance between two aircraft and affect the number of takeoff and landing operations on a single runway under Instrument Meteorological Conditions (IMC). The AVOSS concept seeks to safely reduce aircraft separation distances, when weather conditions permit, to increase the operational capacity of major airports. The current NASA wake-vortex research efforts focus on developing and validating wake vortex encounter models, wake decay and advection models, and wake sensing technologies. These technologies will be incorporated into an automated AVOSS that can properly select safe separation distances for different weather conditions, based on the aircraft pair and predicted/measured vortex behavior. The sensor subsystem efforts focus on developing and validating wake sensing technologies. The lidar system has been field-tested to provide real-time wake vortex trajectory and strength data to AVOSS for wake prediction verification. Wake vortices, atmospheric winds, and turbulence products have been generated from processing the lidar data collected during deployments to Norfolk (ORF), John F. Kennedy (JFK), and Dallas/Fort Worth (DFW) International Airports.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Tenth Biennial Coherent Laser Radar Technology and Applications Conference; 12-15; NASA/CP-1999-209758
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    A Priori Subgrid Analysis of Temporal Mixing Layers with Evaporating Droplets (1999)
    In:  CASI
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    Publication Date: 2004-12-03
    Description: Subgrid analysis of a transitional temporal mixing layer with evaporating droplets has been performed using three sets of results from a Direct Numerical Simulation (DNS) database, with Reynolds numbers (based on initial vorticity thickness) as large as 600 and with droplet mass loadings as large as 0.5. In the DNS, the gas phase is computed using a Eulerian formulation, with Lagrangian droplet tracking. The Large Eddy Simulation (LES) equations corresponding to the DNS are first derived, and key assumptions in deriving them are first confirmed by computing the terms using the DNS database. Since LES of this flow requires the computation of unfiltered gas-phase variables at droplet locations from filtered gas-phase variables at the grid points, it is proposed to model these by assuming the gas-phase variables to be the sum of the filtered variables and a correction based on the filtered standard deviation; this correction is then computed from the Subgrid Scale (SGS) standard deviation. This model predicts the unfiltered variables at droplet locations considerably better than simply interpolating the filtered variables. Three methods are investigated for modeling the SGS standard deviation: the Smagorinsky approach, the Gradient model and the Scale-Similarity formulation. When the proportionality constant inherent in the SGS models is properly calculated, the Gradient and Scale-Similarity methods give results in excellent agreement with the DNS.
    Keywords: Fluid Mechanics and Thermodynamics
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    Heat Transfer on a Film-Cooled Rotating Blade Using Different Turbulence Models (1999)
    In:  Other Sources
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    Publication Date: 2011-08-23
    Description: A three-dimensional Navier Stokes code has been used to compute the heat transfer coefficient on a film-cooled, rotating turbine blade. The blade chosen is the ACE rotor with five rows containing 93 film cooling holes covering the entire span. This is the only film-cooled rotating blade over which experimental data is available for comparison. Over 2.278 million grid points are used to compute the flow over the blade including the tip clearance region. using Wilcox's k-omega model, Coakley's q-omega model, and the zero-equation Baldwin-Lomax (B-L) model. A reasonably good comparison with the experimental data is obtained on the suction surface for all the turbulence models. At the leading edge, the B-L model yields a better comparison than tile two-equation models. On the pressure surface however the comparison between the experimental data and the prediction from the k-omega model is much better than from the other two models. Overall, the k-omega model provides the best comparison with the experimental data. However, the two-equation models require at least 40% more computational resources than the B-L model.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: International Journal of Heat and Mass Transfer (ISSN 0017-9310); Volume 42; 789-802
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    T(sub lambda) Depression by a Heat Current Along the lambda-Line (1999)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: We report measurements of the depression of the superfluid transition temperature by a heat current (1 less than or = Q less than or = 100 microW/sq cm) along the lambda-line (SVP less than or = P less than or = 21.6 bar). At P = 21.6 bar, measurements were also performed in a reduced gravity (0.2g). Experimental results show that the pressure dependence of the depression and the gravity effect on the measurements are small, in qualitative agreement with theoretical predictions. Keywords: superfluid helium; Lambda transition; heat current
    Keywords: Fluid Mechanics and Thermodynamics
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    A Validated All-Pressure Fluid Drop Model and Lewis Number Effects for a Binary Mixture (1999)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The differences between subcritical liquid drop and supercritical fluid drop behavior are discussed. Under subcritical, evaporative high emission rate conditions, a film layer is present in the inner part of the drop surface which contributes to the unique determination of the boundary conditions; it is this film layer which contributes to the solution's convective-diffusive character. In contrast, under supercritical condition as the boundary conditions contain a degree of arbitrariness due to the absence of a surface, and the solution has then a purely diffusive character. Results from simulations of a free fluid drop under no-gravity conditions are compared to microgravity experimental data from suspended, large drop experiments at high, low and intermediary temperatures and in a range of pressures encompassing the sub-and supercritical regime. Despite the difference between the conditions of the simulations and experiments (suspension vs. free floating), the time rate of variation of the drop diameter square is remarkably well predicted in the linear curve regime. The drop diameter is determined in the simulations from the location of the maximum density gradient, and agrees well with the data. It is also shown that the classical calculation of the Lewis number gives qualitatively erroneous results at supercritical conditions, but that an effective Lewis number previously defined gives qualitatively correct estimates of the length scales for heat and mass transfer at all pressures.
    Keywords: Fluid Mechanics and Thermodynamics
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    Study of Flow of Superfluid He-II Very Near Tau(sub lambda) (1999)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: We report here, preliminary data from an experiment studying flow of superfluid helium through a slit orifice (of sub-micron width) very close to T(sub lambda). Critical supercurrent (I(sub c)) data is obtained from a step function drive to the diaphragm in a Helmholtz resonator cell. The superfluid density (rho(sub s)) data can be obtained from the resonant frequency of the Helmholtz oscillator, as determined by transfer function of the resonator or from the free ringing after the step function excitation. Preliminary data shows that I(sub c) is proportional to (rho(sub s))(exp 1.27) and rho(sub s)) is proportional to tau(exp 0.73), where tau is the reduced temperature. However, the magnitude of I(sub c) is much larger than expected, indicating a possible parallel flow path. Further investigations are in progress. Keywords: superfluid; hydrodynamics; critical exponent
    Keywords: Fluid Mechanics and Thermodynamics
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    A Textbook for a First Course in Computational Fluid Dynamics (1999)
    In:  CASI
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    Publication Date: 2013-08-29
    Description: This paper describes and discusses the textbook, Fundamentals of Computational Fluid Dynamics by Lomax, Pulliam, and Zingg, which is intended for a graduate level first course in computational fluid dynamics. This textbook emphasizes fundamental concepts in developing, analyzing, and understanding numerical methods for the partial differential equations governing the physics of fluid flow. Its underlying philosophy is that the theory of linear algebra and the attendant eigenanalysis of linear systems provides a mathematical framework to describe and unify most numerical methods in common use in the field of fluid dynamics. Two linear model equations, the linear convection and diffusion equations, are used to illustrate concepts throughout. Emphasis is on the semi-discrete approach, in which the governing partial differential equations (PDE's) are reduced to systems of ordinary differential equations (ODE's) through a discretization of the spatial derivatives. The ordinary differential equations are then reduced to ordinary difference equations (O(Delta)E's) using a time-marching method. This methodology, using the progression from PDE through ODE's to O(Delta)E's, together with the use of the eigensystems of tridiagonal matrices and the theory of O(Delta)E's, gives the book its distinctiveness and provides a sound basis for a deep understanding of fundamental concepts in computational fluid dynamics.
    Keywords: Fluid Mechanics and Thermodynamics
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    Large Eddy Simulation of a Forced Round Turbulent Buoyant Plume in Neutral Surroundings (1999)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: Buoyant flows play an important role in various technological and environmental issues. For example, dispersal of pollutants, smoke, or volcano exhaust in the atmosphere, vertical motion of air, formation of clouds and other weather systems, and flows in cooling towers and fires are all determined primarily by buoyancy effects. The buoyancy force in such flows can originate from either a heat source or due to different densities between a fluid and its surroundings. Whatever the cause, the flow can be understood by studying the effects of the tight coupling between the thermal and the velocity fields since density differences can be characterized as temperature differences.
    Keywords: Fluid Mechanics and Thermodynamics
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    Formation of Sprays From Conical Liquid Sheets (1999)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: Our objective is to predict droplet size distributions created by fuel injector nozzles in Jet turbines. These results will be used to determine the initial conditions for numerical simulations of the combustion process in gas turbine combustors. To predict the droplet size distribution, we are currently constructing a numerical model to understand the instability and breakup of thin conical liquid sheets. This geometry serves as a simplified model of the liquid jet emerging from a real nozzle. The physics of this process is difficult to study experimentally as the time and length scales are very short. From existing photographic data, it does seem clear that three-dimensional effects such as the formation of streamwise ligaments and the pulling back of the sheet at its edges under the action of surface tension are important.
    Keywords: Fluid Mechanics and Thermodynamics
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    Experimental Investigation of Boundary Layer Behavior in a Simulated Low Pressure Turbine (1999)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: A detailed investigation of the flow physics occurring on the suction side of a simulated Low Pressure Turbine (LPT) blade was performed. A contoured upper wall was designed to simulate the y pressure distribution of an actual LPT blade onto a flat plate. The experiments were carried out at Reynolds numbers of 100,000 and 250,000 with three levels of freestream turbulence. The main emphasis in this paper is placed on flow field surveys performed at a y Reynolds number of 100,000 with levels of freestream turbulence ranging from 0.8% to 3%. Smoke-wire flow visualization data was used to confirm that the boundary layer was separated and formed a bubble. The transition process over the separated flow region is observed to be similar to a laminar free shear layer flow with the formation of a large coherent eddy structure. For each condition, the locations defining the separation bubble were determined by careful examination of pressure and mean velocity profile data. Transition onset location and length determined from intermittency profiles decrease as freestream turbulence levels increase. Additionally, the length and height of the laminar separation bubbles were observed to be inversely proportional to the levels of freestream turbulence.
    Keywords: Fluid Mechanics and Thermodynamics
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    Aspects of Turbulent / Non-Turbulent Interfaces (1999)
    In:  CASI
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    Publication Date: 2013-08-29
    Description: A distinct boundary between turbulent and non-turbulent regions in a fluid of otherwise constant properties is found in many laboratory and engineering turbulent flows, including jets, mixing layers, boundary layers and wakes. Generally, the flow has mean shear in at least one direction within t he turbulent zone, but the non-turbulent zones have no shear (adjacent laminar shear is a different case, e.g. transition in a boundary layer). There may be purely passive differences between the turbulent and non-turbulent zones, e.g. small variations in temperature or scalar concentration, for which turbulent mixing is an important issue. The boundary has several major characteristics of interest for the present study. Firstly, the boundary advances into the non-turbulent fluid, or in other words, nonturbulent fluid is entrained. Secondly, the change in turbulence properties across the boundary is remarkably abrupt; strong turbulent motions come close to the nonturbulent fluid, promoting entrainment. Thirdly, the boundary is irregular with a continually changing convoluted shape, which produces statistical intermittency. Its shape is contorted at all scales of the turbulent motion.
    Keywords: Fluid Mechanics and Thermodynamics
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    Comparison of AGE and Spectral Methods for the Simulation of Far-Wakes (1999)
    In:  CASI
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    Publication Date: 2013-08-29
    Description: Turbulent flow simulation methods based on finite differences are attractive for their simplicity, flexibility and efficiency, but not always for accuracy or stability. This report demonstrates that a good compromise is possible with the Advected Grid Explicit (AGE) method. AGE has proven to be both efficient and accurate for simulating turbulent free-shear flows, including planar mixing layers and planar jets. Its efficiency results from its localized fully explicit finite difference formulation (Bisset 1998a,b) that is very straightforward to compute, outweighing the need for a fairly small timestep. Also, most of the successful simulations were slightly under-resolved, and therefore they were, in effect, large-eddy simulations (LES) without a sub-grid-scale (SGS) model, rather than direct numerical simulations (DNS). The principle is that the role of the smallest scales of turbulent motion (when the Reynolds number is not too low) is to dissipate turbulent energy, and therefore they do not have to be simulated when the numerical method is inherently dissipative at its resolution limits. Such simulations are termed 'auto-LES' (LES with automatic SGS modeling) in this report.
    Keywords: Fluid Mechanics and Thermodynamics
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    Reversal in Spreading of a Tabbed Circular Jet Under Controlled Excitation (1997)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Detailed flow field measurements have been carried out for a turbulent circular jet perturbed by tabs and artificial excitation. Two "delta tabs" were placed at the nozzle exit at diametricall opposite y locations. The excitation condition involved subharmonic resonance that manifested in a periodic vortex pairing in the near flow field. While the excitation and the tabs independently increased jet spreading, a combination of the two diminished the effect. The jet spreading was most pronounced with the tabs but was reduced when excitation was applied to the tabbed jet. The tabs generated streamwise vortex pairs that caused a lateral spreading of the jet in a direction perpendicular to the plane containing the tabs. ne excitation, on the other hand, organized the azimuthal vorticity into coherent ring structures whose evolution and pairing also increased entrainment by the jet. In the tabbed case, the excitation produced coherent azimuthal structures that were distorted and asymmetric in shape. The self-induction of these structures produced an effect that opposed the tendency for the lateral spreading of the streamwise vortex pairs. The passage of the distorted vortices, and their pairing, also had a cancellation effect on the time-averaged streamwise vorticity field. These led to the reduction in jet spreading.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Physics of Fluids; Volume 9; No. 12; 3733-3741
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    Computation of Transonic Flows Using Potential Methods (1997)
    In:  Other Sources
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    Publication Date: 2011-08-23
    Description: The proposed paper will describe the state of the art associated with numerical solution of the full or exact velocity potential equation for solving transonic, external-aerodynamic flows. The presentation will begin with a review of the literature emphasizing research activities of the past decade. Next, the various forms of the full or exact velocity potential equation, the equation's corresponding mathematical characteristics, and the derivation assumptions will be presented and described in detail. Impact of the derivation assumptions on simulation accuracy, especially with respect to shock wave capture, will be presented and discussed relative to the more complete Euler or Navier-Stokes formulations. The technical presentation will continue with a description of recently developed full potential numerical approach characteristics. This description will include governing equation nondimensionalization, physical-to-computational-domain mapping procedures, a limited description of grid generation requirements, the spatial discretization scheme, numerical implementation of boundary conditions, and the iteration scheme. The next portion of the presentation will present and discuss numerical results for several two- and three-dimensional aerodynamic applications. Included in the results section will be a discussion and demonstration of a typical grid refinement analysis for determining spatial convergence of the numerical solution and level of solution accuracy. Computer timings for a variety of full potential applications will be compared and contrasted with similar results for the Euler equation formulation. Finally. the presentation will end with concluding remarks and recommendations for future work.
    Keywords: Fluid Mechanics and Thermodynamics
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    Waterjet Impeller (1996)
    In:  CASI
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    Publication Date: 2018-06-09
    Description: North American Marine Jet (NAMJ), Inc. received assistance from Marshall Space Flight Center engineers in the Computational Fluid Dynamics (CFD) branch of the Structure and Dynamics Laboratory in improving the proposed design of a new impeller for their jet-propulsion systems. Marshall used advanced CFD techniques, which included creating a three-dimensional computer model of the impeller for analysis. With Marshall input, the company modified the design, then Marshall used a computer model to make a solid polycarbonate model. The rapid prototyping allowed the company to avoid many time- consuming and costly steps in creating the impeller model. NAMJ is now able to compete with Pacific-area and European manufacturers who have traditionally dominated the market.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Spinoff 1996; 102; NASA/NP-1996-10-222-HQ
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    Miniature Heat Pipes (1997)
    In:  CASI
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    Publication Date: 2018-06-09
    Description: Small Business Innovation Research contracts from Goddard Space Flight Center to Thermacore Inc. have fostered the company work on devices tagged "heat pipes" for space application. To control the extreme temperature ranges in space, heat pipes are important to spacecraft. The problem was to maintain an 8-watt central processing unit (CPU) at less than 90 C in a notebook computer using no power, with very little space available and without using forced convection. Thermacore's answer was in the design of a powder metal wick that transfers CPU heat from a tightly confined spot to an area near available air flow. The heat pipe technology permits a notebook computer to be operated in any position without loss of performance. Miniature heat pipe technology has successfully been applied, such as in Pentium Processor notebook computers. The company expects its heat pipes to accommodate desktop computers as well. Cellular phones, camcorders, and other hand-held electronics are forsible applications for heat pipes.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Spinoff 1997; 100; NASA/NP-1997-08-226-HQ
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    Go With the Flow (1998)
    In:  CASI
    Details
    Publication Date: 2018-06-09
    Description: Under SBIR (Small Business Innovative Research) contracts with Lewis Research Center, Nektonics, Inc., developed coating process simulation tools, known as Nekton. This powerful simulation software is used specifically for the modeling and analysis of a wide range of coating flows including thin film coating analysis, polymer processing, and glass melt flows. Polaroid, Xerox, 3M, Dow Corning, Mead Paper, BASF, Mitsubishi, Chugai, and Dupont Imaging Systems are only a few of the companies that presently use Nekton.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Spinoff 1998; 85; NASA/NP-1998-09-241-HQ
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    Customized Hermetic Feedthrough Developed to Isolate Fluids (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: A common problem occurs when refrigerant fluids wick inside the insulation of thermocouple wires through a compressor's casing feedthrough and then leak into the adjacent disconnect box outside the casing. Leaking fluids create an unfavorable situation inside the disconnect box and may contaminate the fluids. To address this problem, NASA Lewis Research Center s Manufacturing Engineering Division developed a customized hermetic feedthrough for a bank of Worthington compressors. In these compressors, bearing temperatures are measured by internal thermocouples embedded in bearings located inside the compressor casings. The thermocouple wires need to be routed outside the casing and read at another location. These wires are short and are terminated to a disconnect strip inside the casing. The bearings operate at about 170 F, but because the casing is filled with R12 refrigerant oil, the casing has a maximum temperature of about 100 F. The operating conditions of these compressors permit the use of an epoxy that is compatible with the R12 fluid. The desired finished product is a stainless steel tube that has been filled solid with epoxy after thermocouple wires bonded and sealed by epoxy have been inserted through its length. Shrink tubing extends from both ends of the tube. The process that was developed to isolate the thermocouple wires from the R12 fluid follows. For this application, use an 8-in.-long piece of 0.500-in. 304 stainless steel tube with six pairs of 24-gauge stranded, PTFE-insulated (polytetrafluoroethylene) type "T" thermocouple wires for each feedthrough. Use shrink tubing to strain relief the insulated wires at their exit from the stainless steel tube. Cut the wire to length and identify the location of the stainless steel tube sleeve with masking tape. Then, remove the outer insulation from a 2-in. section of wire that will be inside the tube, and carefully strip to bare wire a 1-in. section in the middle of the section with the outer insulation removed. For an effective seal, the epoxy must penetrate between the strands when stranded conductors are used. Make the seal with epoxy bond on the bare wire. The bare wire must be encapsulated with a thin layer of the epoxy that leaves only a very low profile. These encapsulated wires must cure before the assembly can be continued. Then, inspect the cured wires for complete encapsulation before going to the next step. Insert the wires in the stainless steel tube and orient them so that the epoxied stripped sections are staggered within the tube; then, apply shrink tubing to one end of the cleaned wires, positioning it inside the edge of the tube. The small gaps between the wires on the other end will be used to inject the epoxy into the tube. Let the epoxy cure inside the tube, free of any voids. Then, continue to fill the tube until the entire 8-in. length is nearly filled, allowing room for the other strain-relieving shrink tubing. Since this first design, the process has been adjusted to fit many needs and situations. Customized feedthroughs have been assembled from various wire types, wire gauges, and/or stainless steel tube passages. The fittings selected to mount these feedthroughs allow their use in other areas, such as pressure or vacuum systems.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1998; NASA/TM-1999-208815
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    Multidisciplinary Probabilistic Heat Transfer/Structural Analysis Code Developed: NESTEM (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: High-Speed Civil Transport (HSCT) engine combustor liners are subjected to complex thermal environments and have to endure these for thousands of hours with assured reliability. In the past, several deterministic analyses have been performed, including detailed heat transfer analyses to obtain thermal profiles and deterministic stress analyses to identify critical locations of high stresses. Actual rig tests also have been performed for segments by simulating these loading situations as closely as possible. However, it is well known that many uncertainties exist in loading (primarily thermal loads due to heat transfer), boundary conditions (end fixity unknowns), and material properties (moduli, thermal-expansion coefficients, and conductivities). The present in-house effort at the NASA Lewis Research Center is directed toward accounting for these in a formal way to assess the performance of liner components under complex and uncertain loading conditions as well as subject to other geometry- and material-related uncertainties.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1998; NASA/TM-1999-208815
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    Fiber-Supported Droplet Combustion Experiment-2 (1998)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: A major portion of the energy produced in the world today comes from the burning of liquid hydrocarbon fuels in the form of droplets. Understanding the fundamental physical processes involved in droplet combustion is not only important in energy production but also in propulsion, in the mitigation of combustion-generated pollution, and in the control of the fire hazards associated with handling liquid combustibles. Microgravity makes spherically symmetric combustion possible, allowing investigators to easily validate their droplet models without the complicating effects of gravity. The Fiber-Supported Droplet Combustion (FSDC-2) investigation was conducted in the Microgravity Glovebox facility of the shuttles' Spacelab during the reflight of the Microgravity Science Laboratory (MSL- 1R) on STS-94 in July 1997. FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and duo droplets with and without forced air convection. FSDC-2 is sponsored by the NASA Lewis Research Center, whose researchers are working in cooperation with several investigators from industry and academia. The rate at which a droplet burns is important in many commercial applications. The classical theory of droplet burning assumes that, for an isolated, spherically symmetric, single-fuel droplet, the gas-phase combustion processes are much faster than the droplet surface regression rate and that the liquid phase is at a uniform temperature equal to the boiling point. Recent, more advanced models predict that both the liquid and gas phases are unsteady during a substantial portion of the droplet's burning history, thus affecting the instantaneous and average burning rates, and that flame radiation is a dominant mechanism that can extinguish flames in a microgravity environment. FSDC-2 has provided well-defined, symmetric droplet burning data including radiative emissions to validate these theoretical models for heptane, decane, ethanol, and methanol fuels. Since most commercial combustion systems burn droplets in a convective environment, data were obtained without and with convective flow over the burning droplet (see the following photos).
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1997; NASA/TM-1998-206312
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    Measurement of Gust Response on a Turbine Cascade (1997)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: This in-house experiment on the gust response of an annular turbine cascade was particularly designed to provide data to compare with the results of a typical, linearized gust-response analysis. Reduced frequency, Mach number, and incidence were varied independently. Except for the lowest reduced frequency, the gust velocity distribution was nearly sinusoidal. For the high inlet-velocity series of tests, the cascade was near choking. The mean flow was documented by measuring blade surface pressures and the cascade exit flow, and high-response pressure transducers were used to measure the unsteady pressure distribution. Inlet-velocity components and turbulence parameters were measured using hot wire anemometry. In addition to the synchronous time-averaged pressure spectra, typical power spectra are included for several representative conditions.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1996; NASA-TM-107350
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    Effects of Rotor Wake on Film Cooling Investigated (1997)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: Through a combination of experimental and computational studies, researchers at the NASA Lewis Research Center investigated the effect of upstream blade-row wake passing on the showerhead (leading edge) film cooling of a downstream turbine. The experiments were performed in a steady-flow annular turbine cascade facility equipped with an upstream rotating row of cylindrical rods to produce a periodic wake field similar to that found in an actual turbine. Spanwise, chordwise, and temporal resolution of the blade surface temperature were achieved through the use of an array of nickel thin-film surface gauges covering one unit cell of a showerhead film hole pattern. Film effectiveness and Nusselt numbers were determined for a test matrix of various injectants, injectant blowing ratios, and wake Strouhal numbers (St).
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1996; NASA-TM-107350
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    Controls/CFD Interdisciplinary Research Software Generates Low-Order Linear Models for Control Design From Steady-State CFD Results (1997)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: The NASA Lewis Research Center is developing analytical methods and software tools to create a bridge between the controls and computational fluid dynamics (CFD) disciplines. Traditionally, control design engineers have used coarse nonlinear simulations to generate information for the design of new propulsion system controls. However, such traditional methods are not adequate for modeling the propulsion systems of complex, high-speed vehicles like the High Speed Civil Transport. To properly model the relevant flow physics of high-speed propulsion systems, one must use simulations based on CFD methods. Such CFD simulations have become useful tools for engineers that are designing propulsion system components. The analysis techniques and software being developed as part of this effort are an attempt to evolve CFD into a useful tool for control design as well. One major aspect of this research is the generation of linear models from steady-state CFD results. CFD simulations, often used during the design of high-speed inlets, yield high resolution operating point data. Under a NASA grant, the University of Akron has developed analytical techniques and software tools that use these data to generate linear models for control design. The resulting linear models have the same number of states as the original CFD simulation, so they are still very large and computationally cumbersome. Model reduction techniques have been successfully applied to reduce these large linear models by several orders of magnitude without significantly changing the dynamic response. The result is an accurate, easy to use, low-order linear model that takes less time to generate than those generated by traditional means. The development of methods for generating low-order linear models from steady-state CFD is most complete at the one-dimensional level, where software is available to generate models with different kinds of input and output variables. One-dimensional methods have been extended somewhat so that linear models can also be generated from two- and three-dimensional steady-state results. Standard techniques are adequate for reducing the order of one-dimensional CFD-based linear models. However, reduction of linear models based on two- and three-dimensional CFD results is complicated by very sparse, ill-conditioned matrices. Some novel approaches are being investigated to solve this problem.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1996; NASA-TM-107350
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    Coupled Aerodynamic-Thermal-Structural (CATS) Analysis (1995)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: Coupled Aerodynamic-Thermal-Structural (CATS) Analysis is a focused effort within the Numerical Propulsion System Simulation (NPSS) program to streamline multidisciplinary analysis of aeropropulsion components and assemblies. Multidisciplinary analysis of axial-flow compressor performance has been selected for the initial focus of this project. CATS will permit more accurate compressor system analysis by enabling users to include thermal and mechanical effects as an integral part of the aerodynamic analysis of the compressor primary flowpath. Thus, critical details, such as the variation of blade tip clearances and the deformation of the flowpath geometry, can be more accurately modeled and included in the aerodynamic analyses. The benefits of this coupled analysis capability are (1) performance and stall line predictions are improved by the inclusion of tip clearances and hot geometries, (2) design alternatives can be readily analyzed, and (3) higher fidelity analysis by researchers in various disciplines is possible. The goals for this project are a 10-percent improvement in stall margin predictions and a 2:1 speed-up in multidisciplinary analysis times. Working cooperatively with Pratt & Whitney, the Lewis CATS team defined the engineering processes and identified the software products necessary for streamlining these processes. The basic approach is to integrate the aerodynamic, thermal, and structural computational analyses by using data management and Non-Uniform Rational B-Splines (NURBS) based data mapping. Five software products have been defined for this task: (1) a primary flowpath data mapper, (2) a two-dimensional data mapper, (3) a database interface, (4) a blade structural pre- and post-processor, and (5) a computational fluid dynamics code for aerothermal analysis of the drum rotor. Thus far (1) a cooperative agreement has been established with Pratt & Whitney, (2) a Primary Flowpath Data Mapper has been prototyped and delivered to General Electric Aircraft Engines and Pratt & Whitney for evaluation, (3) a collaborative effort has been initiated with the National Institute of Standards and Testing to develop a Standard Data Access Interface, and (4) a blade tip clearance capability has been implemented into the Structural Airfoil Blade Engineering Routine (SABER) program. We plan to continue to develop the data mappers and data management tools. As progress is made, additional efforts will be made to apply these tools to propulsion system applications.
    Keywords: Fluid Mechanics and Thermodynamics
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    Cooperative Testing of Rocket Injectors That Use Gaseous Oxygen and Hydrogen (1995)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: Gaseous oxygen and hydrogen propellants used in a special engine energy cycle called Full-Flow Staged Combustion are believed to significantly increase the lifetime of a rocket engine's pumps. The cycle can also reduce the operating temperatures of the engine. Improving the lifetime of the hardware reduces its overall maintenance and operations costs, and is critical to reducing costs for the joint NASA/industry Reusable Launch Vehicle (RLV). The work in this project will demonstrate the performance and lifetime of one-element and many-element combustors with gaseous O2/H2 injectors. This work supporting the RLV program is a cooperative venture of the NASA Lewis Research Center, the NASA Marshall Space Flight Center, Rocketdyne, and the Pennsylvania State University. Information about gas-gas rocket injector performance with O2/H2 is very limited. Because of this paucity of data, new testing is needed to improve the knowledge base for testing and designing new injectors for the RLV and to improve computer models that predict the combusting gas flows of new injector designs. Therefore, detailed observations and measurements of the combusting flow from many-element injectors in a rocket engine are being sought. These observations and measurements will be done with three different tools: schlieren photography, ultraviolet imaging, and Raman spectroscopy. The schlieren system will take photos of the density differences in combusting flow, the ultraviolet movies will determine the location of the hydroxyl (OH) radical in the combustion flow, and the Raman spectroscopic measurements will provide the combustion temperature and amount of water (H2O), hydrogen (H2), and oxygen (O2) in the combustor. Marshall is providing overall program management, design and computational fluid dynamics (CFD) analyses, as well as funding for the work at Penn State. An existing, windowed combustor and several injectors will be provided by Rocketdyne--two injectors for the initial screening tests and one with an optimized design based on the best design found in the screening tests. Lewis will provide a nozzle and several injectors for the screening test program. The configuration of the injectors will be based on a design chosen by all the participants, and their elements will be based on the coaxial and impinging flow. Lewis also will provide the instrumentation for the flow-field measurements: schlieren, ultraviolet imaging, and Raman spectroscopy. In addition, thermocouples will measure heat flow on the injector face. Other traditional measurements of rocket performance will be made as well: chamber pressure, mass flow of each propellant, purge flow, and the barrier cooling gas flow. Penn State will conduct single-element testing with the injector elements from both the Rocketdyne and the jointly designed injectors. A wide variety of traditional and nontraditional injector designs will be tested in this program. The results will be valuable in computational fluid dynamics code validation and overall rocket combustion efficiency measurements. Correlations between combustion efficiency, laser measurements of species, and ultraviolet and visible light photography will also be made. Thus far, several different single-element injectors have been tested at Penn State and Lewis. The experimental setup of a rocket engine with a viewing window is shown. The combusting flow is shown. The results are helping engineers design the many element injectors.
    Keywords: Fluid Mechanics and Thermodynamics
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    Simulation of Three-Dimensional Symmetric and Asymmetric Instabilities in Attachment-Line Boundary Layers (1996)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: On a swept wing, contamination along the leading edge, Tollmien-Schlichting waves, stationary or traveling crossflow vortices, and/or Taylor-Gortler vortices can cause the catastrophic breakdown of laminar to turbulent flow, which leads to increased skin-friction drag for the aircraft. The discussion in this Note will be limited to disturbances which evolve along the attachment line (leading edge of swept wing). If the Reynolds number of the attachment-line boundary layer is greater than some critical value, then the complete wing is inevitably engulfed in turbulent flow. Essentially, there are two critical Reynolds number points that must be considered. The first is for small-amplitude disturbances, and the second is for bypass transition. The present study will use direct numerical simulations to validate a linear 2D-eigenvalue prediction method based on parabolized stability equations by Lin and Malik. This method is considered because it suggests that a number of symmetric and asymmetric modes exist and are stable or unstable on the attachment line depending on the Reynolds number. If validated, the approach would predict a number of modes which are linearly damped in the Reynolds number regime 100 to 245; however, these modes may grow nonlinearly and provide an explanation to this region.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Journal; Volume 34; No. 11; 2432-2434
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    Absolute Equilibrium Entropy (1997)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: The entropy associated with absolute equilibrium ensemble theories of ideal, homogeneous, fluid and magneto-fluid turbulence is discussed and the three-dimensional fluid case is examined in detail. A sigma-function is defined, whose minimum value with respect to global parameters is the entropy. A comparison is made between the use of global functions sigma and phase functions H (associated with the development of various H-theorems of ideal turbulence). It is shown that the two approaches are complimentary though conceptually different: H-theorems show that an isolated system tends to equilibrium while sigma-functions allow the demonstration that entropy never decreases when two previously isolated systems are combined. This provides a more complete picture of entropy in the statistical mechanics of ideal fluids.
    Keywords: Fluid Mechanics and Thermodynamics
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    Direct Simulation of Evolution and Control of Three-Dimensional Instabilities in Attachment-Line Boundary Layers (1995)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: The spatial evolution of three-dimensional disturbances in an attachment-line boundary layer is computed by direct numerical simulation of the unsteady, incompressible Navier-Stokes equations. Disturbances are introduced into the boundary layer by harmonic sources that involve unsteady suction and blowing through the wall. Various harmonic- source generators are implemented on or near the attachment line, and the disturbance evolutions are compared. Previous two-dimensional simulation results and nonparallel theory are compared with the present results. The three-dimensional simulation results for disturbances with quasi-two-dimensional features indicate growth rates of only a few percent larger than pure two-dimensional results; however, the results are close enough to enable the use of the more computationally efficient, two-dimensional approach. However, true three-dimensional disturbances are more likely in practice and are more stable than two-dimensional disturbances. Disturbances generated off (but near) the attachment line spread both away from and toward the attachment line as they evolve. The evolution pattern is comparable to wave packets in at-plate boundary-layer flows. Suction stabilizes the quasi-two-dimensional attachment-line instabilities, and blowing destabilizes these instabilities; these results qualitatively agree with the theory. Furthermore, suction stabilizes the disturbances that develop off the attachment line. Clearly, disturbances that are generated near the attachment line can supply energy to attachment-line instabilities, but suction can be used to stabilize these instabilities.
    Keywords: Fluid Mechanics and Thermodynamics
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    Fluidic Control of Nozzle Flow: Some Performance Measurements (1995)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: Results are presented of an experimental program that investigated the use of a secondary air stream to control the amount of flow through a convergent-divergent nozzle. These static tests utilized high pressure, ambient temperature air that was injected at the throat of the nozzle through an annular slot. Multiple injection slot sizes and injection angles were tested. The introduction of secondary flow was made in an opposing direction to the primary flow and the resulting flow field caused the primary stream to react as though the physical throat size had been reduced. The percentage reduction in primary flow rate was generally about twice the injected flow rate. The most effective throttling was achieved by injecting through the smallest slot in an orientation most nearly opposed to the approaching primary flow. Thrust edliciency, as measured by changes in nozzle thrust coefficient, was highest at high nozzle pressure ratios, NPR. The static test results agreed with predictions obtained prior from PABSD, a fully viscous computational fluid dynamics program. Since use of such an injection system on gas turbine engine exhaust nozzles would be primarily at high NPRs, it was concluded that fluidic control holds promise for reducing nozzle weight and complexity on future systems.
    Keywords: Fluid Mechanics and Thermodynamics
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    Aerodynamic Performance and Flow-Field Characteristics of Two Waverider-Derived Hypersonic Cruise Configurations (1995)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: The component integration of a class of hypersonic high-lift configurations known as waveriders into hypersonic cruise vehicles was evaluated. A wind-tunnel model was developed which integrates realistic vehicle components with two waverider shapes, referred to as the straight-wing and cranked-wing shapes. Both shapes were conical-flow-derived waveriders for a design Mach number of 4.0. Experimental data and limited computational fluid dynamics (CFD) predictions were obtained over a Mach number range of 1.6 to 4.63 at a Reynolds number of 2.0 x 10(exp 6) per foot. The CFD predictions and flow visualization data confirmed the shock attachment characteristics of the baseline waverider shapes and illustrated the waverider flow-field properties. Experimental data showed that no significant performance degradations, in terms of maximum lift-to-drag ratios, occur at off-design Mach numbers for the waverider shapes and the integrated configurations. A comparison of the fully-integrated waverider vehicles to the baseline shapes showed that the performance was significantly degraded when all of the components were added to the waveriders, with the most significant degradation resulting from aftbody closure and the addition of control surfaces. Both fully-integrated configurations were longitudinally unstable over the Mach number range studied with the selected center of gravity location and for unpowered conditions. The cranked-wing configuration provided better lateral-directional stability characteristics than the straight-wing configuration.
    Keywords: Fluid Mechanics and Thermodynamics
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    Dual-Code Solution Strategy for Chemically-Reacting Hypersonic Flows (1995)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: A new procedure seeks to combine the thin-layer Navier-Stokes solver LAURA with the parabolized Navier-Stokes solver UPS for the aerothermodynamic solution of chemically-reacting air flow fields. The interface protocol is presented and the method is applied to two slender, blunted shapes. Both axisymmetric and three-dimensional solutions are included with surface pressure and heat transfer comparisons between the present method and previously published results. The case of Mach 25 flow over an axisymmetric six degree sphere-cone with a non-catalytic wall is considered to 100 nose radii. A stability bound on the marching step size was observed with this case and is attributed to chemistry effects resulting from the non-catalytic wall boundary condition. A second case with Mach 28 flow over a sphere-cone-cylinder-flare configuration is computed at both two and five degree angles of attack with a fully-catalytic wall. Surface pressures are seen to be within five percent with the present method compared to the baseline LAURA solution and heat transfers are within 10 percent. The effect of grid resolution is investigated in both the radial and streamwise directions. The procedure demonstrates significant, order of magnitude reductions in solution time and required memory for the three-dimensional case in comparison to an all thin-layer Navier-Stokes solution.
    Keywords: Fluid Mechanics and Thermodynamics
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    Simulation of Nonlinear Instabilities in an Attachment-Line Boundary Layer (1996)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: The linear and the nonlinear stability of disturbances that propagate along the attachment line of a three-dimensional boundary layer is considered. The spatially evolving disturbances in the boundary layer are computed by direct numerical simulation (DNS) of the unsteady, incompressible Navier-Stokes equations. Disturbances are introduced either by forcing at the in ow or by applying suction and blowing at the wall. Quasi-parallel linear stability theory and a nonparallel theory yield notably different stability characteristics for disturbances near the critical Reynolds number; the DNS results con rm the latter theory. Previously, a weakly nonlinear theory and computations revealed a high wave-number region of subcritical disturbance growth. More recent computations have failed to achieve this subcritical growth. The present computational results indicate the presence of subcritically growing disturbances; the results support the weakly nonlinear theory. Furthermore, an explanation is provided for the previous theoretical and computational discrepancy. In addition, the present results demonstrate that steady suction can be used to stabilize disturbances that otherwise grow subcritically along the attachment line.
    Keywords: Fluid Mechanics and Thermodynamics
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    Relaxation Revisited: A Fresh Look at Multigrid for Steady Flows (1997)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: The year 1971 saw the publication of one of the landmark papers in computational aerodynamics, that of Murman and Cole. As with many seminal works, its significance lies not so much in the specific problem that it addressed| small disturbance, plane transonic flow - but in the identification of a general approach to the solution of a technically important and theoretically difficult problem. The key features of Murman and Cole's work were the use of type- dependent differencing to correctly account for the proper domain of dependence of a mixed elliptic/hyperbolic equation, and the introduction of line relaxation to solve the steady flow equation. All subsequent work in transonic potential flows was based on these concepts. Jameson extended Murman and Cole's ideas to the full potential equation with two important contributions. First, he introduced the rotated difference stencil, which generalized the Murman and Cole type-dependent difference operator to general coordinates. Second, he used the interpretation, introduced by Garabedian, of relaxation as an iteration in artificial time to construct stable relaxation schemes, generalizing the original line relaxation method of Reference. The decade of the 1970s saw an explosion of activity in the solution of transonic potential flows, which has been summarized in the review article of Caughey.
    Keywords: Fluid Mechanics and Thermodynamics
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    Overview of Active Flow Control at NASA Langley Research Center (1998)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: The paper summarizes Active Flow Control projects currently underway at the NASA Langley Research Center. Technology development is being pursued within a multidisciplinary, cooperative approach, involving the classical disciplines of fluid mechanics, structural mechanics, material science, acoustics, and stability and control theory. Complementing the companion papers in this session, the present paper will focus on projects that have the goal of extending the state-of-the-art in the measurement, prediction, and control of unsteady, nonlinear aerodynamics. Toward this goal, innovative actuators, micro and macro sensors, and control strategies are considered for high payoff flow control applications. The target payoffs are outlined within each section below. Validation of the approaches range from bench-top experiments to wind-tunnel experiments to flight tests. Obtaining correlations for future actuator and sensor designs are implicit in the discussion. The products of the demonstration projects and design tool development from the fundamental NASA R&D level technology will then be transferred to the Applied Research components within NASA, DOD, and US Industry. Keywords: active flow control, separation control, MEMS, review
    Keywords: Fluid Mechanics and Thermodynamics
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    DSMC Simulation of Shock/Shock Interactions: Emphasis on Type IV Interactions (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: This paper presents the results of a numerical study of shock/shock interactions that include both the Edney type IV and type III interactions, with emphasis on the type IV interactions. Computations are made using the direct simulation Monte Carlo (DSMC) method of Bird for Mach 10 air flow, as produced in the ONERA R5Ch low-density wind tunnel. The simulations include the flow about a shock generator which creates a relatively weak oblique shock that impinges on a much stronger cylinder bow shock. The sensitivity and characteristics of the interactions are examined by varying the horizontal distance separating the shock generator leading edge and cylinder. Results of the simulation for one separation distance are compared with wind tunnel measurements. Comparisons are made for surface heating and pressure and for flow-field values of density and rotational temperatures, as obtained with the Dual-line Coherent Anti-Stokes Scattering (DL-CARS) technique. The comparisons between experiment and calculation yield a consistent description of the shock interaction features and a consistent description of the surface heating and pressure distributions, with the exception of the peak values-the computed values being greater than the measured values.
    Keywords: Fluid Mechanics and Thermodynamics
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    Receptivity and Bypass Dynamics (1999)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: Problems concerning laminar-turbulent transition are addressed by solving a series of initial value problems. Solutions to the temporal, initial-value problem .with an inhomogeneous forcing term imposed upon the flow are sought. It is shown that: (1) A transient disturbance lying located outside of the boundary layer can lead to the growth of an unstable Tollmein-Schlicting wave; (2) A resonance with the continuous spectrum may provide a mechanism for bypass transition; and (3) The continuum modes of a disturbance feed directly into the Tollmein-Schlicting wave downstream through non-parallel effects.
    Keywords: Fluid Mechanics and Thermodynamics
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    Multistage Turbomachinery Flows Simulated Numerically (1999)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: At the NASA Lewis Research Center, a comprehensive assessment was made of the predictive capability of the average passage flow model as applied to multistage axial-flow compressors. This model, which describes the time-averaged flow field within a typical passage of a blade row embedded in a multistage configuration, is being widely used throughout U.S. aircraft industry as an integral part of their design systems. Rotor flow-angle deviation. In this work, detailed data taken within a four and one-half stage large low-speed compressor were used to assess the weaknesses and strengths of the predictive capabilities of the average passage flow model. The low-speed compressor blading is of modern design and employs stator end-bends. Measurements were made with slow- and high response instrumentation. The high-response measurements revealed the velocity components of both the rotor and stator wakes. From the measured wake profiles, we found that the flow exiting the rotors deviated from the rotor exit metal angle to a lesser degree than was predicted by the average passage flow model. This was found to be due to blade boundary layer transition, which recently has been shown to exist on multistage axial compressor rotor and stator blades, but was not accounted for in the average passage model. Consequently, a model that mimics the effects of blade boundary layer transition, Shih k-epsilon model, was incorporated into the average passage model. Simulations that incorporated this transition model showed a dramatic improvement in agreement with data. The altered model thus improved predictive capability for multistage axial-flow compressors, and this was verified by detailed experimental measurement.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1998; NASA/TM-1999-208815
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    Inlet-Compressor Analysis Performed Using Coupled Computational Fluid Dynamics Codes (1999)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: A thorough understanding of dynamic interactions between inlets and compressors is extremely important to the design and development of propulsion control systems, particularly for supersonic aircraft such as the High-Speed Civil Transport (HSCT). Computational fluid dynamics (CFD) codes are routinely used to analyze individual propulsion components. By coupling the appropriate CFD component codes, it is possible to investigate inlet-compressor interactions. The objectives of this work were to gain a better understanding of inlet-compressor interaction physics, formulate a more realistic compressor-face boundary condition for time-accurate CFD simulations of inlets, and to take a first step toward the CFD simulation of an entire engine by coupling multidimensional component codes. This work was conducted at the NASA Lewis Research Center by a team of civil servants and support service contractors as part of the High Performance Computing and Communications Program (HPCCP).
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1998; NASA/TM-1999-208815
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    Application of Doppler Global Velocimetry to Supersonic Flows (1996)
    In:  CASI
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    Publication Date: 2018-06-02
    Description: The design and implementation of Doppler Global Velocimetry (DGV) for testing in the Langley Unitary Plan Wind Tunnel is presented. The discussion begins by outlining the characteristics of the tunnel and the test environment, with potential problem areas highlighted. Modifications to the optical system design to implement solutions for these problems are described. Since this tunnel entry was the first ever use of DGV in a supersonic wind tunnel, the test series was divided into three phases, each with its own goal. Phase I determined if condensation provided sufficient scattered light for DGV applications. Phase II studied particle lag by measuring the flow about an oblique shock above an inclined flat plate. Phase III investigated the supersonic vortical flow field above a 75-degree delta wing at 24-degrees angle of attack. Example results from these tests are presented.
    Keywords: Fluid Mechanics and Thermodynamics
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    Effects of H2O Vapor on Vibrational Relaxation in Expanding and Contracting Flows (1996)
    In:  CASI
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    Publication Date: 2018-06-02
    Description: As opposed to previous explanations based on the effects of anharmonicity of simple diatomic molecules, traces of water vapor are suggested to be the most likely cause of the anomalously fast vibrational relaxation of such gases observed in supersonic and hypersonic nozzles. The mechanism is the strong V-VR coupling with H2O molecules that dramatically facilitates the collisional transfer of vibrational energy. Slight moisture content is thus a real world aspect of gas dynamics that must be considered in characterizations of shock tubes, reflected shock tunnels, and expansion tubes.
    Keywords: Fluid Mechanics and Thermodynamics
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    Static Aeroelastic Analysis of Transonic Wind Tunnel Models Using Finite Element Methods (1997)
    In:  CASI
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    Publication Date: 2018-06-02
    Description: A computational method for accurately predicting the static aeroelastic deformations of typical transonic transport wind tunnel models is described. The method utilizes a finite element method (FEM) for predicting the deformations. Extensive calibration/validation of this method was carried out using a novel wind-off wind tunnel model static loading experiment and wind-on optical wing twist measurements obtained during a recent wind tunnel test in the National Transonic Facility (NTF) at NASA LaRC. Further validations were carried out using a Navier-Stokes computational fluid dynamics (CFD) flow solver to calculate wing pressure distributions about several aeroelastically deformed wings and comparing these predictions with NTF experimental data. Results from this aeroelastic deformation method are in good overall agreement with experimentally measured values. Including the predicted deformations significantly improves the correlation between CFD predicted and experimentally measured wing & pressures.
    Keywords: Fluid Mechanics and Thermodynamics
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    Bleed Hole Flow Phenomena Studied (1997)
    In:  CASI
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    Publication Date: 2018-06-02
    Description: Boundary-layer bleed is an invaluable tool for controlling the airflow in supersonic aircraft engine inlets. Incoming air is decelerated to subsonic speeds prior to entering the compressor via a series of oblique shocks. The low momentum flow in the boundary layer interacts with these shocks, growing in thickness and, under some conditions, leading to flow separation. To remedy this, bleed holes are strategically located to remove mass from the boundary layer, reducing its thickness and helping to maintain uniform flow to the compressor. The bleed requirements for any inlet design are unique and must be validated by extensive wind tunnel testing to optimize performance and efficiency. To accelerate this process and reduce cost, researchers at the NASA Lewis Research Center initiated an experimental program to study the flow phenomena associated with bleed holes. Knowledge of these flow properties will be incorporated into computational fluid dynamics (CFD) models that will aid engine inlet designers in optimizing bleed configurations before any hardware is fabricated. This ongoing investigation is currently examining two hole geometries, 90 and 20 (both with 5-mm diameters), and various flow features.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1996; NASA-TM-107350
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    Conceptual Design Method Developed for Advanced Propulsion Nozzles (1998)
    In:  CASI
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    Publication Date: 2018-06-02
    Description: As part of a contract with the NASA Lewis Research Center, a simple, accurate method of predicting the performance characteristics of a nozzle design has been developed for use in conceptual design studies. The Nozzle Performance Analysis Code (NPAC) can predict the on- and off-design performance of axisymmetric or two-dimensional convergent and convergent-divergent nozzle geometries. NPAC accounts for the effects of overexpansion or underexpansion, flow divergence, wall friction, heat transfer, and small mass addition or loss across surfaces when the nozzle gross thrust and gross thrust coefficient are being computed. NPAC can be used to predict the performance of a given nozzle design or to develop a preliminary nozzle system design for subsequent analysis. The input required by NPAC consists of a simple geometry definition of the nozzle surfaces, the location of key nozzle stations (entrance, throat, exit), and the nozzle entrance flow properties. NPAC performs three analysis "passes" on the nozzle geometry. First, an isentropic control volume analysis is performed to determine the gross thrust and gross thrust coefficient of the nozzle. During the second analysis pass, the skin friction and heat transfer losses are computed. The third analysis pass couples the effects of wall shear and heat transfer with the initial internal nozzle flow solutions to produce a system of equations that is solved at steps along the nozzle geometry. Small mass additions or losses, such as those resulting from leakage or bleed flow, can be included in the model at specified geometric sections. A final correction is made to account for divergence losses that are incurred if the nozzle exit flow is not purely axial.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1997; NASA/TM-1998-206312
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    On Some Numerical Dissipation Schemes (1998)
    In:  CASI
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    Publication Date: 2018-06-02
    Description: Several schemes for introducing an artificial dissipation into a central difference approximation to the Euler and Navier Stokes equations are considered. The focus of the paper is on the convective upwind and split pressure (CUSP) scheme, which is designed to support single interior point discrete shock waves. This scheme is analyzed and compared in detail with scalar dissipation and matrix dissipation (MATD) schemes. Resolution capability is determined by solving subsonic, transonic, and hypersonic flow problems. A finite-volume discretization and a multistage time-stepping scheme with multigrid are used to compute solutions to the flow equations. Numerical solutions are also compared with either theoretical solutions or experimental data. For transonic airfoil flows the best accuracy on coarse meshes for aerodynamic coefficients is obtained with a simple MATD scheme. The coarse-grid accuracy for the original CUSP scheme is improved by modifying the limiter function used with the scheme, giving comparable accuracy to that obtained with the MATD scheme. The modifications reduce the background dissipation and provide control over the regions where the scheme can become first order.
    Keywords: Fluid Mechanics and Thermodynamics
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    Aircraft Laminar Flow Control (1998)
    In:  CASI
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    Publication Date: 2018-06-02
    Description: Aircraft laminar flow control (LFC) from the 1930's through the 1990's is reviewed and the current status of the technology is assessed. Examples are provided to demonstrate the benefits of LFC for subsonic and supersonic aircraft. Early studies related to the laminar boundary-layer flow physics, manufacturing tolerances for laminar flow, and insect-contamination avoidance are discussed. LFC concept studies in wind-tunnel and flight experiments are the major focus of the paper. LFC design tools are briefly outlined for completeness.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Annual Review of Fluid Mechanics 1998; Volume 30; 1-29
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    Combustion Instabilities Modeled (1999)
    In:  CASI
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    Publication Date: 2018-06-02
    Description: NASA Lewis Research Center's Advanced Controls and Dynamics Technology Branch is investigating active control strategies to mitigate or eliminate the combustion instabilities prevalent in lean-burning, low-emission combustors. These instabilities result from coupling between the heat-release mechanisms of the burning process and the acoustic flow field of the combustor. Control design and implementation require a simulation capability that is both fast and accurate. It must capture the essential physics of the system, yet be as simple as possible. A quasi-one-dimensional, computational fluid dynamics (CFD) based simulation has been developed which may meet these requirements. The Euler equations of mass, momentum, and energy have been used, along with a single reactive species transport equation to simulate coupled thermoacoustic oscillations. A very simple numerical integration scheme was chosen to reduce computing time. Robust boundary condition procedures were incorporated to simulate various flow conditions (e.g., valves, open ends, and choked inflow) as well as to accommodate flow reversals that may arise during large flow-field oscillations. The accompanying figure shows a sample simulation result. A combustor with an open inlet, a choked outlet, and a large constriction approximately two thirds of the way down the length is shown. The middle plot shows normalized, time-averaged distributions of the relevant flow quantities, and the bottom plot illustrates the acoustic mode shape of the resulting thermoacoustic oscillation. For this simulation, the limit cycle peak-to-peak pressure fluctuations were 13 percent of the mean. The simulation used 100 numerical cells. The total normalized simulation time was 50 units (approximately 15 oscillations), which took 26 sec on a Sun Ultra2.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1998; NASA/TM-1999-208815
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    Radiation Heat Transfer Modeling Improved for Phase-Change, Thermal Energy Storage Systems (1998)
    In:  CASI
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    Publication Date: 2018-06-02
    Description: Spacecraft solar dynamic power systems typically use high-temperature phase-change materials to efficiently store thermal energy for heat engine operation in orbital eclipse periods. Lithium fluoride salts are particularly well suited for this application because of their high heat of fusion, long-term stability, and appropriate melting point. Considerable attention has been focused on the development of thermal energy storage (TES) canisters that employ either pure lithium fluoride (LiF), with a melting point of 1121 K, or eutectic composition lithium-fluoride/calcium-difluoride (LiF-20CaF2), with a 1040 K melting point, as the phase-change material. Primary goals of TES canister development include maximizing the phase-change material melt fraction, minimizing the canister mass per unit of energy storage, and maximizing the phase-change material thermal charge/discharge rates within the limits posed by the container structure.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1997; NASA/TM-1998-206312
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    Pulse Phase Thermography for Defect Detection and Visualization (1999)
    In:  CASI
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    Publication Date: 2018-06-02
    Description: Pulse Phase Thermography (PPT) has been reported as a novel powerful technique of the thermal NDE. It employs application of the Discrete Fourier Transform (DFT) to thermal images obtained following flash heating of the front surface of a specimen. The computed phasegrams are excellent for defect visualization in a wide range of materials. This is in part due to their low sensitivity to uneven heating. This work is an attempt to analyze advantages and limitations of PPT. Results of application of the DFT to simulated temperature decays are presented. The temperature evolution on a surface has been simulated based on an analytical solution of the one-dimensional heat diffusion problem. A more sophisticated study has been done for different sizes of defects using numerical solution of the three-dimensional mathematical model. Capabilities of PPT for in-depth scanning and for monitoring of the material loss are discussed. The recommendations for the practical application of the PPT are presented. Experimental results obtained following these recommendations are reported.
    Keywords: Fluid Mechanics and Thermodynamics
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    Decoupling the Roles of Inertia and Gravity on Particle Dispersion (1999)
    In:  CASI
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    Publication Date: 2017-10-02
    Description: Inertial and gravitational forces determine a particle's motion in a turbulent flow field. Gravity plays the dominant role in this motion by pulling the particles through adjacent regions of fluid turbulence. To better understand and model how a particle's inertia effects its displacement, one must examine the dispersion in a turbulent flow in the absence of gravity. In this paper, we present the particle experiments planned for NASA's KC-135 Reduced-Gravity Aircraft, which generates microgravity conditions for about 20 seconds. We also predict the particle behavior using simulation and ground-based experiments. We will release particles with Stokes numbers of 0.1, 1, and 10 into an enclosed tank of near-isotropic, stationary, and homogenous turbulence. These particle Stoke numbers cover a broad range of flow regimes of interest. Two opposed grids oscillating back and forth generate the turbulent field in the tank with a range of turbulence scales that covers about three orders of magnitude and with turbulence intensities of about ten times the mean velocity. The motion of the particles will be tracked using a stereo image velocimetry technique.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Proceedings of the Fourth Microgravity Fluid Physics and Transport Phenomena Conference; 83-87; NASA/CP-1999-208526/SUPPL1
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    Acoustic Streaming in Microgravity: Flow Stability and Heat Transfer Enhancement (1999)
    In:  CASI
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    Publication Date: 2017-10-02
    Description: Experimental results are presented for drops and bubbles levitated in a liquid host, with particular attention given to the effect of shape oscillations and capillary waves on the local flow fields. Some preliminary results are also presented on the use of streaming flows for the control of evaporation rate and rotation of electrostatically levitated droplets in 1 g. The results demonstrate the potential for the technological application of acoustic methods to active control of forced convection in microgravity.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Proceedings of the Fourth Microgravity Fluid Physics and Transport Phenomena Conference; 497-502; NASA/CP-1999-208526/SUPPL1
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    Flow-induced birefringence measurement system using dual-crystal transverse electro-optic modulator for microgravity fluid physics applications (1999)
    In:  CASI
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    Publication Date: 2017-10-02
    Description: We have developed a new instrument that can measure fast transient birefringence and polymer chain orientation angle in complex fluids. The instrument uses a dual-crystal transverse electro-optic modulator with the second crystal's modulation voltage applied 180 deg out of phase from that of the first crystal. In this manner, the second crystal compensates for the intrinsic static birefringence of the first crystal, and it doubles the modulation depth. By incorporating a transverse electro-optic modulator with two lithium-niobate (LiNbO3) crystals oriented orthogonal to each other with a custom-designed optical system, we have produced a very small robust instrument capable of fast transient retardation measurements. By measuring the sample thickness or optical path length through the sample, we can calculate the transient birefringence. This system can also measure dichroism. We have compared the calibration results and retardation and orientation angle measurements of this instrument with those of a photoelastic modulator (PEM) based system using a quarter wave plate and a high-precision 1/16-wave plate to simulate a birefringent sample. Transient birefringence measurements on the order of 10(exp -9) can be measured using either modulator.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Proceedings of the Fourth Microgravity Fluid Physics and Transport Phenomena Conference; 510-515; NASA/CP-1999-208526/SUPPL1
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    Microgravity Experiments to Evaluate Electrostatic Forces in Controlling Cohesion and Adhesion of Granular Materials (1999)
    In:  CASI
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    Publication Date: 2017-10-02
    Description: The bulk behavior of dispersed, fluidized, or undispersed stationary granular systems cannot be fully understood in terms of adhesive/cohesive properties without understanding the role of electrostatic forces acting at the level of the grains themselves. When grains adhere to a surface, or come in contact with one another in a stationary bulk mass, it is difficult to measure the forces acting on the grains, and the forces themselves that induced the cohesion and adhesion are changed. Even if a single grain were to be scrutinized in the laboratory, it might be difficult, perhaps impossible, to define the distribution and character of surface charging and the three-dimensional relationship that charges (electrons, holes) have to one another. The hypothesis that we propose to test in microgravity (for dielectric materials) is that adhesion and cohesion of granular matter are mediated primarily by dipole forces that do not require the presence of a net charge; in fact, nominally electrically neutral materials should express adhesive and cohesive behavior when the neutrality results from a balance of positive and negative charge carriers. Moreover, the use of net charge alone as a measure of the electrical nature of grain-to-grain relationships within a granular mass may be misleading. We believe that the dipole forces arise from the presence of randomly-distributed positive and negative fixed charge carriers on grains that give rise to a resultant dipole moment. These dipole forces have long-range attraction. Random charges are created whenever there is triboelectrical activity of a granular mass, that is, whenever the grains experience contact/separation sequences or friction.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Proceedings of the Fourth Microgravity Fluid Physics and Transport Phenomena Conference; 370-378; NASA/CP-1999-208526/SUPPL1
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    Investigation of Nucleate Boiling Mechanisms Under Microgravity Conditions (1999)
    In:  CASI
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    Publication Date: 2017-10-02
    Description: The present work is aimed at the experimental studies and numerical modeling of the bubble growth mechanisms of a single bubble attached to a heating surface and of a bubble sliding along an inclined heated plate. Single artificial cavity of 10 microns in diameter was made on the polished Silicon wafer which was electrically heated at the back side in order to control the surface nucleation superheat. Experiments with a sliding bubble were conducted at different inclination angles of the downward facing heated surface for the purpose of studying the effect of magnitude of components of gravity acting parallel to and normal to the heat transfer surface. Information on the bubble shape and size, the bubble induced liquid velocities as well as the surface temperature were obtained using the high speed imaging and hydrogen bubble techniques. Analytical/numerical models were developed to describe the heat transfer through the micro-macro layer underneath and around a bubble formed at a nucleation site. In the micro layer model the capillary and disjoining pressures were included. Evolution of the bubble-liquid interface along with induced liquid motion was modeled. As a follow-up to the studies at normal gravity, experiments are being conducted in the KC-135 aircraft to understand the bubble growth/detachment under low gravity conditions. Experiments have been defined to be performed under long duration of microgravity conditions in the space shuttle. The experiment in the space shuttle will provide bubble growth and detachment data at microgravity and will lead to validation of the nucleate boiling heat transfer model developed from the preceding studies conducted at normal and low gravity (KC-135) conditions.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Proceedings of the Fourth Microgravity Fluid Physics and Transport Phenomena Conference; 435-440; NASA/CP-1999-208526/SUPPL1
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    Bubble Dynamics on a Heated Surface (1999)
    In:  CASI
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    Publication Date: 2017-10-02
    Description: In this work, we study steady and oscillatory thermocapillary and natural convective flows generated by a bubble on a heated solid surface. The interaction between gas and vapor bubbles with the surrounding fluid is of interest for both space and ground-based processing. A combined numerical-experimental approach is adopted here. The temperature field is visualized using Mach-Zehnder and/or Wollaston Prism Interferometry and the flow field is observed by a laser sheet flow visualization technique. A finite element numerical model is developed which solves the transient two-dimensional continuity, momentum, and energy equations and includes the effects of temperature-dependent surface tension and bubble surface deformation. Below the critical Marangoni number, the steady state low-g and 1-g temperature and velocity fields predicted by the finite element model are in excellent agreement with both the visualization experiments in our laboratory and recently published experimental results in the literature. Above the critical Marangoni number, the model predicts an oscillatory flow which is also closely confirmed by experiments. It is shown that the dynamics of the oscillatory flow are directly controlled by the thermal and hydrodynamic interactions brought about by combined natural and thermocapillary convection. Therefore, as numerical simulations show, there are considerable differences between the 1-g and low-g temperature and flow fields at both low and high Marangoni numbers. This has serious implications for both materials processing and fluid management in space.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Proceedings of the Fourth Microgravity Fluid Physics and Transport Phenomena Conference; 88-93; NASA/CP-1999-208526/SUPPL1
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    Advanced Subsonic Combustion Rig Developed (1995)
    In:  CASI
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    Publication Date: 2018-06-02
    Description: The Advanced Subsonic Combustion Rig (ASCR), a unique, state-of-the-art facility for conducting combustion research, is located at the NASA Lewis Research Center in Cleveland, Ohio. The ASCR, which was nearing completion at the close of 1995, will be capable of simulating the very high pressure and high temperature conditions that are expected to exist in future, advanced subsonic gas turbine (jet) engines. Future environmental regulations will require much cleaner burning (more environmentally friendly) aircraft engines. The ASCR is critical to the development of these cleaner engines. It will allow NASA and U.S. aircraft engine industry researchers to identify and test promising clean-burning gas turbine engine combustion concepts under the pressure and temperature conditions that are expected for those future engines. Combustion processes will be investigated for a variety of next-generation aircraft engine sizes, including engines for large, long-range aircraft (with typical trip lengths of about 3000 mi) and for regional aircraft (with typical trip lengths of about 400 mi). The ASCR design was conceived and initiated in 1993, and fabrication and construction of the rig, including the buildup of an advanced control room, took place throughout 1994 and 1995. In early 1996, the ASCR will be operational for obtaining research data. The ASCR is an intricate part of the NASA Advanced Subsonic Technology Propulsion Program, which is aimed at developing technologies critical to the next generation of gas turbine engines. This effort is in collaboration with the U.S. aircraft gas turbine engine industry. A goal of the Advanced Subsonic Technology Propulsion Program is to develop combustion concepts and technologies that will result in gas turbine engines that produce 50 percent less nitrous oxide (NO_x) pollutants than current engines do. This facility is unique in its capability to simulate advanced subsonic engine pressure, temperature, and air flow rate conditions. Specifically, it will provide operating temperatures up to 3000 F and pressures up to 60 atm. Under these conditions, researchers will obtain detailed combustion temperatures, pressures, and flow velocities as well as the chemical compositions of the combustion exhaust. Researchers also will be able to obtain data by using nonintrusive laser diagnostic techniques. The ASCR facility will be used to test fundamental combustion configurations (flametubes) for detailed study of combustion processes, to test sectors of gas turbine combustors to study the process in configurations more like those of aircraft engines, and in some cases to test full annular combustors.
    Keywords: Fluid Mechanics and Thermodynamics
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    Coupled Monte Carlo Probability Density Function/ SPRAY/CFD Code Developed for Modeling Gas-Turbine Combustor Flows (1995)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: The success of any solution methodology for studying gas-turbine combustor flows depends a great deal on how well it can model various complex, rate-controlling processes associated with turbulent transport, mixing, chemical kinetics, evaporation and spreading rates of the spray, convective and radiative heat transfer, and other phenomena. These phenomena often strongly interact with each other at disparate time and length scales. In particular, turbulence plays an important role in determining the rates of mass and heat transfer, chemical reactions, and evaporation in many practical combustion devices. Turbulence manifests its influence in a diffusion flame in several forms depending on how turbulence interacts with various flame scales. These forms range from the so-called wrinkled, or stretched, flamelets regime, to the distributed combustion regime. Conventional turbulence closure models have difficulty in treating highly nonlinear reaction rates. A solution procedure based on the joint composition probability density function (PDF) approach holds the promise of modeling various important combustion phenomena relevant to practical combustion devices such as extinction, blowoff limits, and emissions predictions because it can handle the nonlinear chemical reaction rates without any approximation. In this approach, mean and turbulence gas-phase velocity fields are determined from a standard turbulence model; the joint composition field of species and enthalpy are determined from the solution of a modeled PDF transport equation; and a Lagrangian-based dilute spray model is used for the liquid-phase representation with appropriate consideration of the exchanges of mass, momentum, and energy between the two phases. The PDF transport equation is solved by a Monte Carlo method, and existing state-of-the-art numerical representations are used to solve the mean gasphase velocity and turbulence fields together with the liquid-phase equations. The joint composition PDF approach was extended in our previous work to the study of compressible reacting flows. The application of this method to several supersonic diffusion flames associated with scramjet combustor flow fields provided favorable comparisons with the available experimental data. A further extension of this approach to spray flames, three-dimensional computations, and parallel computing was reported in a recent paper. The recently developed PDF/SPRAY/computational fluid dynamics (CFD) module combines the novelty of the joint composition PDF approach with the ability to run on parallel architectures. This algorithm was implemented on the NASA Lewis Research Center's Cray T3D, a massively parallel computer with an aggregate of 64 processor elements. The calculation procedure was applied to predict the flow properties of both open and confined swirl-stabilized spray flames.
    Keywords: Fluid Mechanics and Thermodynamics
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    CFD-Based Design Optimization Tool Developed for Subsonic Inlet (1995)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: The traditional approach to the design of engine inlets for commercial transport aircraft is a tedious process that ends with a less-than-optimum design. With the advent of high-speed computers and the availability of more accurate and reliable computational fluid dynamics (CFD) solvers, numerical optimization processes can effectively be used to design an aerodynamic inlet lip that enhances engine performance. The designers' experience at Boeing Corporation showed that for a peak Mach number on the inlet surface beyond some upper limit, the performance of the engine degrades excessively. Thus, our objective was to optimize efficiency (minimize the peak Mach number) at maximum cruise without compromising performance at other operating conditions. Using a CFD code NPARC, the NASA Lewis Research Center, in collaboration with Boeing, developed an integrated procedure at Lewis to find the optimum shape of a subsonic inlet lip and a numerical optimization code, ADS. We used a GRAPE-based three-dimensional grid generator to help automate the optimization procedure. The inlet lip shape at the crown and the keel was described as a superellipse, and the superellipse exponents and radii ratios were considered as design variables. Three operating conditions: cruise, takeoff, and rolling takeoff, were considered in this study. Three-dimensional Euler computations were carried out to obtain the flow field. At the initial design, the peak Mach numbers for maximum cruise, takeoff, and rolling takeoff conditions were 0.88, 1.772, and 1.61, respectively. The acceptable upper limits on the takeoff and rolling takeoff Mach numbers were 1.55 and 1.45. Since the initial design provided by Boeing was found to be optimum with respect to the maximum cruise condition, the sum of the peak Mach numbers at takeoff and rolling takeoff were minimized in the current study while the maximum cruise Mach number was constrained to be close to that at the existing design. With this objective, the optimum design satisfied the upper limits at takeoff and rolling takeoff while retaining the desirable cruise performance. Further studies are being conducted to include static and cross-wind operating conditions in the design optimization procedure. This work was carried out in collaboration with Dr. E.S. Reddy of NYMA, Inc.
    Keywords: Fluid Mechanics and Thermodynamics
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    WIND Flow Solver Released (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: The WIND code is a general-purpose, structured, multizone, compressible flow solver that can be used to analyze steady or unsteady flow for a wide range of geometric configurations and over a wide range of flow conditions. WIND is the latest product of the NPARC Alliance, a formal partnership between the NASA Lewis Research Center and the Air Force Arnold Engineering Development Center (AEDC). WIND Version 1.0 was released in February 1998, and Version 2.0 will be released in February 1999. The WIND code represents a merger of the capabilities of three existing computational fluid dynamics codes--NPARC (the original NPARC Alliance flow solver), NXAIR (an Air Force code used primarily for unsteady store separation problems), and NASTD (the primary flow solver at McDonnell Douglas, now part of Boeing).
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1998; NASA/TM-1999-208815
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    Mixing of Multiple Jets With a Confined Subsonic Crossflow (1998)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: Results from a recently completed enhanced mixing program are summarized in the two technical papers. These studies were parts of a High Speed Research (HSR)-supported joint Government/industry/university program that involved, in addition to the NASA Lewis Research Center, researchers at United Technologies Research Center, Allison Engine Company, CFD Research Corporation, and the University of California, Irvine. The studies investigated the mixing of jets injected normal to a confined subsonic mainsteam in both rectangular and cylindrical ducts. Experimental and computational studies were performed in both nonreacting and reacting flows. The orifice geometries and flow conditions were selected as typical of the complex three-dimensional flows in the combustion chambers in low-emission gas turbine engines. The principal conclusion from both the experiments and modeling was that the momentum-flux ratio J and orifice spacing S/H were the most significant flow and geometry variables, respectively. Conserved scalar distributions were similar-independent of reaction, orifice diameter H/d, and shape-when the orifice spacing and the square root of the momentum-flux ratio were inversely proportional. Jet penetration was critical, and penetration decreased as either momentum-flux ratio or orifice spacing decreased. We found that planar averages must be considered in context with the distributions. The mass-flow ratios and the orifices investigated were often very large. The jet-to-mainstream mass-flow ratio was varied from significantly less than 1 to greater than 1. The orifice-area to mainstream-cross-sectional-area was varied from approx. 0 to 0.5, and the axial planes of interest were often just downstream of the orifice trailing edge. Three-dimensional flow was a key part of efficient mixing and was observed for all configurations. As an example of the results, the accompanying figure shows the effects of different rates of mass addition on the opposite walls of a rectangular duct.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1997; NASA/TM-1998-206312
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  • 90
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    Calculations of Laminar Heat Transfer Around Cylinders of Arbitrary Cross Section and Transpiration-Cooled Walls with Application to Turbine Blade Cooling (1951)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An approximate method for development of flow and thermal boundary layers in laminar regime on cylinders with arbitrary cross section and transpiration-cooled walls is obtained by use of Karman's integrated momentum equation and an analogous heat-flow equation. Incompressible flow with constant property values throughout boundary layer is assumed. Shape parameters for approximated velocity and temperature profiles and functions necessary for solution of boundary-layer equations are presented as charts, reducing calculations to a minimum. The method is applied to determine local heat-transfer coefficients and surface temperature-cooled turbine blades for a given flow rate. Coolant flow distributions necessary for maintaining uniform blade temperatures are also determined.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-RM-E51F22
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    Impingement of Water Droplets on an Ellipsoid with Fineness Ration 10 in Axisymmetric Flow (1954)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The presence of radomes and instruments that are sensitive to water films or ice formations in the nose section of all-weather aircraft and missiles necessitates a knowledge of the droplet impingement characteristics of bodies of revolution. Because it is possible to approximate many of these bodies with an ellipsoid of revolution, droplet trajectories about an ellipsoid of revolution with a fineness ratio of 10 were computed for incompressible axisymmetric air flow. From the computed droplet trajectories, the following impingement characteristics of the ellipsoid surface were obtained and are presented in terms of dimensionless parameters: (1) total rate of water impingement, (2) extent of droplet impingement zone, and (3) local rate of water impingement. These impingement characteristics are compared briefly with those previously reported for an ellipsoid of revolution with a fineness ratio of 5.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TN-3147
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  • 92
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    Investigation of the Jet Effects on a Flat Surface Downstream of the Exit of a Simulated Turbojet Nacelle at a Free-Stream Mach Number of 2.02 (1954)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An investigation at a free-stream Mach number of 2.02 was made to determine the effects of a propulsive jet on a wing surface located in the vicinity of a choked convergent nozzle. Static-pressure surveys were made on a flat surface that was located in the vicinity of the propulsive jet. The nozzle was operated over a range of exit pressure ratios at different fixed vertical distances from the flat surface. Within the scope of this investigation, it was found that shock waves, formed in the external flow because of the presence of the propulsive jet, impinged on the flat surface and greatly altered the pressure distribution. An integration of this pressure distribution, with the location of the propulsive jet exit varied from 1.450 propulsive-jet exit diameters to 3.392 propulsive-jet exit diameters below the wing, resulted in an incremental lift for all jet locations that was equal to the gross thrust at an exit pressure ratio of 2.86. This incremental lift increased with increase in exit pressure ratio, but not so rapidly as the thrust increased, and was approximately constant at any given exit pressure ratio.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-RM-L54E05a
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    Approximate Turbulent Boundary-Layer Development in Plane Compressible Flow Along Thermally Insulated Surfaces with Application to Supersonic-Tunnel Contour Correction (1950)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Numerical solutions of the differential equation obtained from the momentum theorem for the development of a turbulent boundary layer along a thermally insulated surface in two-dimensional and in radial shock-free flow are presented in tabular form for a range of Mach numbers from 0.100 to 10. The solution can be used in a step-wise procedure with any given distribution of favorable pressure gradients and for zero pressure gradients. Solutions are also given for use with moderate adverse pressure gradients. The mean velocity in the boundary layer is approximated by a power-law profile. In view of the stepwise integration methods to be used, the exponent designated the profile shape can be varied along the surface between the integral fraction limits 1/5 and 1/11 through interpolation. Agreement obtained between theoretical and experimental boundary-layer development in a supersonic nozzle at a nominal Mach number of 2 indicates the general validity of the approximations used in the analysis - in particular, the method of extrapolating low-speed skin-friction relations to high Mach number flows. The extrapolation method used assumes that the skin-friction coefficient depend primarily on Reynolds number, provided that the density and the kinematic viscosity are evaluated at surface conditions.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TN-2045
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    The Condensation Line of Air and the Heats of Vaporization of Oxygen and Nitrogen (1953)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The condensation pressure of air was determined over the range of temperature from 60 to 85 K. The experimental results were slightly higher than the calculated values based on the ideal solution law. Heat of vaporization of oxygen was determined at four temperatures ranging from about 68 to 91 K and of nitrogen similarly at four temperatures ranging from 62 to 78 K.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TN-2969
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  • 95
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    An Analytical Study of Heat Requirements for Icing Protection of Radomes (1953)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The heat requirements for the icing protection of two radome configurations have been studied over a range of design icing conditions. Both the protection limits of a typical thermal protection system and the relative effects of the various icing variables have been determined. For full evaporation of all impinging water, an effective heat density of 14 watts per square inch was required. When a combination of the evaporation and running wet surface systems was employed, a heat requirement of 5 watts per square inch provided protection at severe icing and operating conditions.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-RM-E53A22
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  • 96
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    Generalization of Boundary-Layer Momentum-Integral Equations to Three-Dimensional Flows Including Those of Rotating System (1952)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The Navier-Stokes equations of motion and the equation of continuity are transformed so as to apply to an orthogonal curvilinear coordinate system rotating with a uniform angular velocity about an arbitrary axis in space. A usual simplification of these equations as consistent with the accepted boundary-layer theory and an integration of these equations through the boundary layer result in boundary-layer momentum-integral equations for three-dimensional flows that are applicable to either rotating or nonrotating fluid boundaries. These equations are simplified and an approximate solution in closed integral form is obtained for a generalized boundary-layer momentum-loss thickness and flow deflection at the wall in the turbulent case. A numerical evaluation of this solution carried out for data obtained in a curving nonrotating duct shows a fair quantitative agreement with the measures values. The form in which the equations are presented is readily adaptable to cases of steady, three-dimensional, incompressible boundary-layer flow like that over curved ducts or yawed wings; and it also may be used to describe the boundary-layer flow over various rotating surfaces, thus applying to turbomachinery, propellers, and helicopter blades.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TR-1067
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  • 97
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    Results of Liquid Motion Experiment Analyzed (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: About half of all scientific and commercial spacecraft spin during some part of their mission. Although spinning has many benefits (increasing stability, controlling the location of liquid propellants, and distributing solar heat loads), it also creates problems because a precession (or wobble) motion is unavoidable. For modern spacecraft, by far the largest source of wobble is energy dissipation in the liquid of partially filled tanks. The liquid s energy dissipation cannot, however, be quantified adequately by any ground test. Current analytical models are also inadequate because fundamental data on fluid motion in low gravity are needed to validate them. Consequently, spacecraft attitude-control systems are designed and operated very conservatively. Nonetheless, spacecraft often still perform poorly in orbit, and some have been lost because of a rapid increase of the wobble rate. The Liquid Motion Experiment (LME) was designed to provide spacecraft designers accurate data on the wobble dynamics of spacecraft that contain large quantities of mobile liquids. LME, which was flown on the space shuttle mission STS-84, was built under contract to the NASA Lewis Research Center by the Southwest Research Institute of San Antonio, Texas. Major accomplishments for 1998 include reduction of the flight data and publication of the experimental results. LME was essentially a spin table that created a realistic nutation motion of scale-model tanks containing liquid. Two spherical and two cylindrical transparent tanks were tested simultaneously, and three sets of such tanks were employed to vary liquid viscosity, fill level, and propellant management device (PMD) design. All the tanks were approximately 4.5 in. in diameter. The primary test measurements were the radial and tangential torques exerted on the tanks by the liquid. These torques could not be measured on the ground because of the masking effects of gravity.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1998; NASA/TM-1999-208815
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    LeRC-HT: NASA Lewis Research Center General Multiblock Navier-Stokes Heat Transfer Code Developed (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: For the last several years, LeRC-HT, a three-dimensional computational fluid dynamics (CFD) computer code for analyzing gas turbine flow and convective heat transfer, has been evolving at the NASA Lewis Research Center. The code is unique in its ability to give a highly detailed representation of the flow field very close to solid surfaces. This is necessary for an accurate representation of fluid heat transfer and viscous shear stresses. The code has been used extensively for both internal cooling passage flows and hot gas path flows--including detailed film cooling calculations, complex tip-clearance gap flows, and heat transfer. In its current form, this code has a multiblock grid capability and has been validated for a number of turbine configurations. The code has been developed and used primarily as a research tool (at least 35 technical papers have been published relative to the code and its application), but it should be useful for detailed design analysis. We now plan to make this code available to selected users for further evaluation.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1998; NASA/TM-1999-208815
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  • 99
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    Optical Flow-Field Techniques Used for Measurements in High-Speed Centrifugal Compressors (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: The overall performance of a centrifugal compressor depends on the performance of the impeller and diffuser as well as on the interactions occurring between these components. Accurate measurements of the flow fields in each component are needed to develop computational models that can be used in compressor design codes. These measurements must be made simultaneously over an area that covers both components so that researchers can understand the interactions occurring between the two components. Optical measurement techniques are being used at the NASA Lewis Research Center to measure the velocity fields present in both the impeller and diffuser of a 4:1 pressure ratio centrifugal compressor operating at several conditions ranging from design flow to surge. Laser Doppler Velocimetry (LDV) was used to measure the intrablade flows present in the impeller, and the results were compared with analyses obtained from two three-dimensional viscous codes. The development of a region of low throughflow velocity fluid within this high-speed impeller was examined and compared with a similar region first observed in a large low-speed centrifugal impeller at Lewis. Particle Image Velocimetry (PIV) is a relatively new technique that has been applied to measuring the diffuser flow fields. PIV can collect data rapidly in the diffuser while avoiding the light-reflection problems that are often encountered when LDV is used. The Particle Image Velocimeter employs a sheet of pulsed laser light that is introduced into the diffuser in a quasi-radial direction through an optical probe inserted near the diffuser discharge. The light sheet is positioned such that its centerline is parallel to the hub and shroud surfaces and such that it is parallel to the diffuser vane, thereby avoiding reflections from the solid surfaces. Seed particles small enough to follow the diffuser flow are introduced into the compressor at an upstream location. A high-speed charge-coupled discharge (CCD) camera is synchronized to the laser pulse rate; this allows it to capture images of seed particle position that are separated by a small increment in time. A crosscorrelation of a particle's position in two consecutive images provides an estimate of flow velocity and direction. Multiple image pairs obtained in rapid succession at a particular flow condition provide enough measurements for statistical significance. PIV provides simultaneous velocity measurements over the entire plane that is illuminated by the light sheet instead of at a single point, as is the case when LDV is used. PIV has a further advantage in that the laser light pulse can be triggered by an external source such as a high-response pressure transducer. This feature will allow PIV to synchronize flow imaging to physical phenomena such as rotating stall or stall precursor waves. We hope that this technique can be used to obtain images of the flow field during and just prior to stall.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1998; NASA/TM-1999-208815
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    Thermal Mechanical Stability of Single-Crystal-Oxide Refractive Concentrators Evaluated for High-Temperature Solar-Thermal Propulsion (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: Recently, refractive secondary solar concentrator systems were developed for solar thermal power and propulsion (ref. 1). Single-crystal oxides-such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium aluminum garnet (Y3Al5O12, or YAG), magnesium oxide (MgO), and sapphire (Al2O3)-are candidate refractive secondary concentrator materials. However, the refractive concentrator system will experience high-temperature thermal cycling in the solar thermal engine during the sun/shade transition of a space mission. The thermal mechanical reliability of these components in severe thermal environments is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions. In this research at the NASA Lewis Research Center, a controlled heat flux test approach was developed for investigating the thermal mechanical stability of the candidate oxide. This approach used a 3.0-kW continuous-wave (wavelength, 10.6 mm) carbon dioxide (CO2) laser (ref. 2). The CO2 laser is especially well-suited for single-crystal thermal shock tests because it can directly deliver well-characterized heat energy to the oxide surfaces. Since the oxides are opaque at the 10.6-mm wavelength of the laser beam, the light energy is absorbed at the surfaces rather than transmitting into the crystals, and thus generates the required temperature gradients within the specimens. The following figure is a schematic diagram of the test rig.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 1998; NASA/TM-1999-208815
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