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  • 42.75
  • Aircraft Propulsion and Power
  • ddc:551.7
  • 2000-2004  (508)
  • 1950-1954  (56)
  • 1
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    In:  Zoologische Mededelingen (00240672) vol.78, 1-16 (2004) p.241
    Publication Date: 2015-06-03
    Description: A new species of the genus Allobracon Gahan, 1915, from Brazil is described and illustrated. It is the first green species of the genus and of the subfamily known. A key to the species is added.
    Keywords: Allobracon ; Hymenoptera ; Braconidae ; Hormiinae ; Brazil ; neotropical ; new species ; key ; green pigmentation ; 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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    In:  Zoologische Mededelingen (00240672) vol.78, 1-16 (2004) p.181
    Publication Date: 2007-01-18
    Description: A supplement to the “Revision of the genus Paratropus Gerstaecker” (Kanaar, 1997) is given. Additional faunistic data are presented. The following four new species are described and figured: P. angulifrons (Malaysia: Sabah), P. strigosus (Cameroon, Ghana), P. tenuis (Indonesia: Sumatra) and P. transvalensis (South Africa: Transvaal).
    Keywords: Coleoptera ; Histeridae ; Paratropus ; Termitophiles ; Myrmecophiles ; Africa ; Oriental region ; new species ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 3
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    In:  Zoologische Mededelingen (00240672) vol.78, 1-16 (2004) p.123
    Publication Date: 2007-01-18
    Description: A new species of the genus Phaenocarpa Foerster (Hymenoptera: Braconidae: Alysiinae: Alysiini) from the Atlantic rainforest in Brazil is described and illustrated.
    Keywords: Braconidae ; Alysiinae ; Alysiini ; Phaenocarpa ; Neotropical ; Brazil ; atlantic forest ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 4
    Publication Date: 2007-01-18
    Description: The genus Mama Belokobylskij, 2000 (Braconidae; Euphorinae) is re-assessed and the type species is compared with three similar species: Microctonus cephalicus Provancher, 1886, Microctonus reclinator Ruthe, 1856, and Euphorus spiniscapus Muesebeck, 1936. The results are discussed in relation to the use of taxa based on one specimen (“monotype taxa”). Problems concerning our knowledge of important groups of Euphorinae are outlined. The context of the peculiarly tangled taxonomical situation, which this paper deals with, is considered to be widespread in parasitoid taxonomy, and should be borne in mind in current studies of parasitoid biodiversity assessment.
    Keywords: Mama Belokobylskij ; Microctonus cephalicus Provancher ; Euphorus spiniscapus Muesebeck ; Microctonus reclinator Ruthe ; monotypic genera ; monotype taxa ; biodiversity ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 5
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    In:  Zoologische Mededelingen (00240672) vol.78, 18-28 (2004) p.337
    Publication Date: 2007-01-18
    Description: Two new species of the genus Pambolus Haliday, 1836, (P. leponcei spec. nov., and P. pilcomayensis spec. nov.; Braconidae: Pambolinae) from Argentina are described and illustrated.
    Keywords: Braconidae ; Pambolinae ; Pambolus ; Neotropical ; Argentina ; new species ; partial key ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 6
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    In:  Zoologische Mededelingen (00240672) vol.78, 18-28 (2004) p.331
    Publication Date: 2007-01-18
    Description: Bitomoides gen. nov. (type species: Bitomus latus Papp, 1999) is described and illustrated. In addition Phaedrotoma recondes spec. nov. and Chelonus lukasi nom. nov. are validated.
    Keywords: Hymenoptera ; Braconidae ; Opiinae ; Bitomoides ; Orientopius ; Opius ; Phaedrotoma ; Microchelonus ; Chelonus ; Palaearctic ; Europe ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 7
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    In:  Zoologische Verhandelingen vol.346 (2004) p.1
    Publication Date: 2007-01-22
    Keywords: Dirk Noordam ; in memoriam ; bibliography ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 8
    Publication Date: 2007-01-18
    Description: A new species of the genus Aleiodes Wesmael, 1838 (Braconidae: Rogadinae: Rogadini), A. declanae spec. nov. from New Zealand is described and illustrated. It has been reared from Declana floccosa Walker, Cleora scriptaria (Walker), Pseudocoremia suavis Butler and P. fenerata Felder & Rogenhofer (Geometridae: Ennominae.
    Keywords: Hymenoptera ; Braconidae ; Rogadinae ; Aleiodes ; New Zealand ; Australasian ; Oriental ; East Palaearctic ; new species ; distribution ; partial key ; Geometridae ; Ennominae ; Declana floccosa ; Pseudo-coremia suavis ; Pseudocoremia fenerata ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 9
    Publication Date: 2015-06-03
    Description: Goellneriana deckerti gen. nov. & spec. nov. (Heteroptera: Reduviidae: Phymatinae: Macrocephalini) from Namibia is described and illustrated. Keys to the tribes and to the Afrotropical genera and species of the subfamily Phymatinae are included, a checklist and a distribution map of the Afrotropical ambush bugs is added.
    Keywords: Insecta ; Heteroptera ; Reduviidae ; Phymatinae ; Goellneriana deckerti ; new genus ; new species ; Namibia ; list of Afrotropical Phymatinae ; distribution ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 10
    Publication Date: 2007-01-18
    Description: Three new species of the genera Megischus Brullé and Stephanus Jurine from China (Hymenoptera: Stephanoidea: Stephanidae) are described, illustrated and keyed. Megischus ptosimae Chao, 1964, from Fujian is redescribed and the specimen from India described as M. ptosimae Chao by van Achterberg (2002) is renamed as M. alveolifer spec. nov. and the Malaysian specimen of M. ducalis Westwood listed by van Achterberg (2002) is described as M. ducaloides spec. nov. M. ducalis Westwood, 1851, is reported for the first time from Cambodia, which is the first report after its description. A key to world species of the genus Stephanus is provided.
    Keywords: Hymenoptera ; Stephanoidea ; Stephanidae ; Megischus ; Stephanus ; China ; Oriental ; Palaearctic ; new species ; keys ; Buprestidae ; Cerambycidae ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 11
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.11 (2000) p.19
    Publication Date: 2007-01-10
    Description: New and lesser-known amphipods of hard substrates in the Delta area of the Netherlands (Crustacea: Amphipoda: Gammaridea) The distribution of 27 new and lesser-known amphipod species of sublittoral hard substrates in the Delta area in the southwest of The Netherlands is described. Data from literature on these species are scarce and/or not readily available. They are supplemented with results from recent investigations of mainly sublittoral hard substrates. Of the 22 marine species only nine occur offshore as well as inshore. The others seem to be restricted to inshore man-made coastline protections. This probably reflects the scarcity of hard substrates further offshore. Four invasive species were recorded in the brackish and freshwater part of the Delta area, two of them of pontocaspian origin.
    Keywords: Arthropoda ; Amphipoda ; Gammaridea ; Nederland ; Verspreiding ; Biotopen ; Herkenning ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 12
    Publication Date: 2007-01-18
    Description: The genus Taractrocera is distributed throughout the Oriental and Australian Regions. It contains 16 species, of which two, T. fusca and T. trikora, are described as new in this paper. All species are briefly characterized and the new species are described in full. The phylogeny of the genus is inferred, based on an analysis of morphological and genital characters, both of males and females. The biogeography of the genus is discussed in relation to the phylogeny. The genus has an Australian origin. After some diversification in Australia it dispersed into Asia, in or before the Miocene. It dispersed in the reverse direction, probably before the late-Miocene emergence of the Banda Arc and the Moluccas, 5-6 Mya. Three species are adapted to high altitude, one in the Himalayas and two in New Guinea. Apparently the adaptations occurred independently in the two areas. In New Guinea the high altitude species may have simply been carried up by the Pleistocene and recent uplift of the mountains. Possibly helped by the lowering of the sea-level several times during the Pleistocene, one Australian species colonized some of the Lesser Sunda Islands relatively recently.
    Keywords: Lepidoptera ; Hesperiidae ; Taractrocera ; systematics ; phylogeny ; biogeography ; Indo-australia ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 13
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    In:  Zoologische Mededelingen (00240672) vol.78, 18-28 (2004) p.291
    Publication Date: 2007-01-18
    Description: Neptihormius gen. nov. (type species Neptihormius stigmellae spec. nov. from New Zealand) is described and illustrated. It is a parasitoid of Nepticulidae and the first record of Nepticulidae as host for a member of the subfamily Hormiinae and of basal cyclostome Braconidae.
    Keywords: Hymenoptera ; Braconidae ; Hormiinae ; Neptihormius ; New Zealand ; new genus ; new species ; Australasian ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 14
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    In:  Zoologische Mededelingen (00240672) vol.78, 18-28 (2004) p.313
    Publication Date: 2007-01-18
    Description: Two new subgenera of the genus Xynobius Foerster, 1862, from the Southern Hemisphere are described and illustrated: Paraxynobius (type species Xynobius granulatus spec. nov. from New Zealand), and Sulcynobius (type species X. latisulcus spec. nov. from Sulawesi). One new species of the genus Ademoneuron Fischer, 1988, is added: A. yasirae spec. nov. from Indonesia (Halmahera).
    Keywords: Hymenoptera ; Braconidae ; Opiinae ; Xynobius ; Paraxynobius ; Sulcynobius ; Atormus ; Ademoneuron ; New Zealand ; Indonesia ; Sulawesi ; Halmahera ; new subgenus ; new species ; Australian ; Wallacean ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 15
    Publication Date: 2007-01-18
    Description: The venom apparatus of Pseudoyelicones nigriscutum van Achterberg, 1997 (Braconidae: Rogadinae) is described and illustrated. The venom apparatus morphology of Pseudoyelicones is closely related to that of Bulborogas van Achterberg. Therefore, we propose a sister group relationship between these two genera.
    Keywords: Pseudoyelicones ; venom apparatus ; Bulborogas ; Yelicones ; phylogeny ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 16
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.11 (2000) p.45
    Publication Date: 2007-01-10
    Description: The expansion of the range of the spider Argiope bruennichi in the Netherlands (Araneae: Araneidae) Argiope bruennichi (Scopoli, 1772) is one of the biggest and most colourful spiders in Europe and therefore easy to recognise, even by non-specialists. The species has expanded its range in Germany and Belgium for several decades now and reached the south of The Netherlands in 1980. After the discovery of the first female in the south of the province of Limburg more specimens were found in this region in subsequent years. Later the species was discovered near Herkenbosch, about 30 kilometres to the north. Over the last years the expansion continued rapidly and now almost 300 records are brought together. The species has become widespread in the southern and eastern part of The Netherlands. In 1995 a leap of some 70 kilometres was made, from Limburg to the southern parts of the Veluwe. The years 1998 and 1999 were very good for Argiope, both with over 80 records per year. It is suggested that this expansion is related to the warm and sunny summers in the nineties.
    Keywords: Arthropoda ; Araneae ; Araneidae ; Argiope bruennichi ; Wespenspin ; Wespspin ; Tijgerspin ; Nederland ; Verspreiding ; Biotopen ; Uitbreiding ; Fenologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 17
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    In:  Zoologische Mededelingen (00240672) vol.78, 1-16 (2004) p.1
    Publication Date: 2007-01-18
    Description: The species of the genus Euagathis Szépligeti, 1900 (Braconidae: Agathidinae) from Wallacea and Papua (including Northeast Australia and Solomon Islands) are revised and keyed. Thirty-three species are recognized, of which 11 are new: Euagathis brevitibialis spec. nov. from Papua New Guinea; E. dejongi spec. nov. from Indonesia (Sulawesi); E. fuscistigma spec. nov. from Papua New Guinea; E. kendariensis spec. nov. from Indonesia (Sulawesi); E. maculata spec. nov. from Papua New Guinea; E. mellifacies spec. nov. from Papua New Guinea (Bougainville Island); E. mellisoma spec. nov. from Indonesia (Papua); E. minutoides spec. nov. from Indonesia (Sulawesi); E. novabritanica spec. nov. from Papua New Guinea (New Britain); E. raymondi spec. nov. from Indonesia (Papua); and E. toxopeusi spec. nov. from Indonesia (Papua). Euagathis maculipennoides nom. nov. is a new name for Euagathis maculipennis Szépligeti, 1902, not Brullé, 1846. Agathis etnaella Cameron, 1907, is a new synonym of Cremnops variceps (Cameron, 1907) and Euagathis papua Cameron, 1906, of E. novaguineensis Szépligeti, 1900. New combinations are: Biroia cameroni (Enderlein, 1920); Cremnops papuana (Cameron, 1907); C. varipilosella (Cameron, 1911); C. variceps (Cameron, 1907); and Zelomorpha maculipes (Cameron, 1911).
    Keywords: Braconidae ; Agathidinae ; Disophrini ; Euagathis ; key ; distribution ; synonyms ; Indo-Australian ; Oriental ; Sulawesi ; Moluccas ; New Guinea ; Papua ; Australia ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 18
    Publication Date: 2007-01-10
    Description: Nests of the carpenter ant Camponotus ligniperda in the northwestern part of its range (Hymenoptera: Formicidae) Camponotus ligniperda (Latreille, 1802) is a rare ant species restricted to the eastern part of the Netherlands. Most records relate to a low number of workers. In this paper the species is reported for the first time from the province of Drenthe. Some ecological features of the groundnest are compared with the only other recent nest in the Netherlands. Both nests are located under a decidious tree which protects them from excessive precipitation. In contrast with reports from Germany and Sweden, nesting sites in buildings and houses are not known. It is suggested that the low chances for settlement in our country are due to the wet atlantic climate as well as competition with larger Formica species.
    Keywords: Insecta ; Hymenoptera ; Formicidae ; Camponotus ligniperda ; Nederland ; Verspreiding ; Biotopen ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 19
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    In:  Zoologische Mededelingen (00240672) vol.78, 1-16 (2004) p.77
    Publication Date: 2015-06-03
    Description: Six new genera of the family Braconidae (Hymenoptera) from China are described and illustrated: two genera of the subfamily Agathidinae: Facilagathis gen. nov. (type species: F. spinulata spec. nov.) and Cremnoptoides gen. nov. (type species: Cremnops pappi Sharkey, 1994); one genus of the subfamily Helconinae: Mangshia gen. nov. (type species: M. elongata spec. nov.); two genera of the subfamily Pambolinae: Plesiocedria gen. nov. (type species: P. intermediata spec. nov.) and Apocedria gen. nov. (type species: A. nodifer spec. nov.) and one genus belonging to the subfamily Opiinae: Opiolastes gen. nov. (type species: O. hei spec. nov.). In addition two new species are described: Facilagathis macrocentroides spec. nov. from Zhejiang and Cremnoptoides furcatus spec. nov. from Jilin.
    Keywords: Braconidae ; Agathidinae ; Agathidini ; Disophrini ; Helconinae ; Pambolinae ; Cedriini ; Pambolini ; Opiinae ; Opiini ; Facilagathis ; Cremnoptoides ; Mangshia ; Apocedria ; Plesiocedria ; Opiolastes ; key ; distribution ; Oriental ; Palaearctic ; China. ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 20
    Publication Date: 2022-08-04
    Description: Am nördlichen Harzrand zwischen Benzingerode und Heimburg (Sachsen-Anhalt) konnten bei archäologischen Ausgrabungen mehrere bis zu 100 m lange Aufschlüsse in pleistozänen und holozänen Sedimenten des Hellbach-Schwemmfächers bearbeitet werden. Über pleistozänen Sedimenten eines ca. 2 km breiten Schwemmfächers mit Eiskeilpseudomorphosen, Kryoturbationserscheinungen sowie zentimetermächtigen Lösslagen, sind verschiedene holozäne Kolluvien, Auesedimente und Bodenbildungen auf einem kleineren, ca. 200 m breiten Schwemmfächer abgelagert worden bzw. entstanden. Stellenweise vorhandene Schwarzerdereste sowie mit schwarzem Bodenmaterial gefüllte Pfosten- und Vorratsgruben unterschiedlicher vorgeschichtlicher Epochen deuten auf eine relativ weite Verbreitung von spätpleistozänen und frühholozänen Schwarzerden in der Region hin. Im Auenbereich finden sich an der Basis der holozänen Kolluvien Reste von schwarzen, humosen, stark tonigen Horizonten mit einem lössähnlichen Sediment im Liegenden. Ob es sich hierbei um in situ gebildete Schwarzerden bzw. Schwarze Auenböden oder um anthropogene, durch Brandwirtschaftsweisen geschaffene, schwarze Horizonte handelt, ist noch unklar. Holzkohle aus dem schwarzen Horizont konnte auf rund 5.500 v. Chr. datiert werden. Das lössähnliche Sediment im Liegenden ergab OSL-Alter von ca. 5.910 v. Chr. (7,9 ± 0,5 ka). Nach Ende dieser Stabilitätsphase kam es zu einer oder mehreren größeren Überflutungen des damaligen Auenbereichs. In dieser Aktivitätsphase wurde der schwarze Horizont gekappt und zunächst mit Grobmaterial, später von einer meist 10-20 cm mächtigen feinmaterialreichen, dunkelbraunen Sedimentschicht überlagert. Diese Schicht bildete für längere Zeit die Oberfläche, enthält kaiserzeitliche Funde in situ und wird im Hangenden von gröberen Sedimenten und mächtigen, zweiphasigen mittelalterlichen Auelehmen abgedeckt. Rinnen im jüngsten Auelehm enthalten ziegel- und kalksteinreichen Schotter und repräsentieren vermutlich den letzten Lauf des Hellbachs vor seiner Begradigung in der Mitte des 19. Jahrhunderts. Nach den vorliegenden Befunden ist ein Zusammenhang zwischen den einzelnen fluvialen Aktivitätsphasen und der Besiedlung und Wirtschaftsweise im Einzugsgebiet des Hellbaches sehr wahrscheinlich, kann jedoch nicht zweifelsfrei nachgewiesen werden.
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    Language: German
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  • 21
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    Description: research
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  • 22
    Publication Date: 2022-08-02
    Description: Im östlichen Niedersachsen und westlichen Sachsen-Anhalt wurden in den letzten Jahrzehnten in zwei großen Untersuchungskampagnen mächtige quartäre Ablagerungen beobachtet und dokumentiert. Die Elster-zeitlichen Anteile dieser Ablagerungen sind Gegenstand dieser Veröffentlichung. Ablagerungen der ältesten Vereisung aus diesem Gebiet wurden schon vor über 100 Jahren beschrieben. Im Helmstedter Braunkohlerevier waren über lange Zeit über mächtigen Vorschütt-Schmelzwassersanden zwei Elster-Grundmoränen aufgeschlossen. Stillwasserbildungen verschiedenster Ausbildung waren Zeugen des periglaziären Geschehens in diesem Raum. Am Ende des Pleniglazials kamen in kleinen Seen limnische Sedimente zur Ablagerung, die Hinweise auf mehrere Spätelster-Interstadiale lieferten. Im Zuge einer sehr umfangreichen ingenieurgeologischen Erkundung im nur wenige Kilometer entfernten Allertal bei Morsleben wurden dort einige Jahre später zahlreiche Kernbohrungen niedergebracht und intensiv geologisch dokumentiert und beprobt. Die erbohrten Ablagerungen ähneln den Elster-zeitlichen Sedimenten aus dem Tagebau Schöningen, sind jedoch durch zahlreiche Subrosionssenken noch mächtiger. Hierdurch lassen sich auch mehrere kleine Oszillationen zu Beginn der Überfahrung durch das Elster-Inlandeis nachweisen. An einer Stelle im Allertal ist zudem relativ sicher eine jüngste dritte Elster-Grundmoräne nachweisbar. Die periglazären Bildungen kamen hier in einem eher fluviatil geprägten Milieu zur Ablagerung, das auch die Erhaltung sicher zuordnenbarer Spätelster-Interstadiale behinderte. Eine Korrelation der beobachteten Ablagerungen mit denen anderer Räume ist bisher nur regional, nicht jedoch überregional möglich.
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  • 23
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    Publication Date: 2022-08-02
    Description: An drei Orten im nordwestdeutschen Flachlande konnten zwei Interstadiale der Weichseleiszeit festgestellt werden. Vermutlich gehören die Torfe oberhalb des Interglazials von Eversen bei Rotenburg/Hann. ebenfalls einem dieser Interstadiale an (Wolff & Schröder 1940). Die stratigraphischen Verhältnisse lassen eine eindeutige Eingliederung in die Weichselvereisung zu. In allen Fällen liegen die beiden Torfbänke oberhalb des letzten Interglazials und sind in Sanden der letzten Eiszeit eingeschlossen. Von einer Parallelisierung mit den Stadien der Weichselvereisung soll vorläufig Abstand genommen werden. Durch die Pollenanalyse ergab sich eine Unterteilung in eine Birken- und in eine Kiefernphase. Das Klima war subarktisch-ozeanisch. Die Wiedervereisung nach dem letzten Interglazial und den beiden Interstadialen wurde durch ein feucht-kühles, niederschlagsreiches (vermutlich schneereiches) Klima eingeleitet. Beide Interstadiale haben mit der Alleröd-Oszillation gemeinsame Züge, lassen sich jedoch klar von ihr trennen. Ob eine Unterscheidung der beiden Interstadiale mit Hilfe der Pollenanalyse vorgenommen werden kann, ließen die bisherigen Untersuchungen nicht erkennen und muß daher den weiteren Arbeiten vorbehalten bleiben.
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  • 24
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    Description: research
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  • 25
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  • 26
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  • 27
    Publication Date: 2022-08-05
    Description: research
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  • 28
    Publication Date: 2022-08-05
    Description: research
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  • 29
    Publication Date: 2022-08-05
    Description: research
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  • 30
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    Publication Date: 2022-08-05
    Description: research
    Keywords: ddc:551.7
    Language: German
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  • 31
    Publication Date: 2022-08-05
    Description: In den Lössdeckschichten des Steinbruchs Mainz-Weisenau (Heidelberger Zement AG) sind im Hangenden des letztinterglazialen Bodens drei Altwürmhumuszonen aufgeschlossen (Mosbacher Humuszonen). Auf der Grundlage einer detaillierten Profilbeschreibung erfolgte eine lückenlose Entnahme von Sedimentproben zur Untersuchung der Molluskenfaunen. Die Aussage des Fossilberichts wird durch die Anwesenheit von verlagerten Sedimenten unter und zwischen den Humuszonen und die Möglichkeit einer sekundären Einmischung von Schalenmaterial beeinträchtigt. Dennoch lässt der Fossilbericht nach dem letzten Interglazial drei Wärmeschwankungen erkennen, die mit den Humuszonen korrelierbar sind. In den Sedimenten zwischen Eemboden und unterer Humuszone sowie zwischen mittlerer und oberer Humuszone wurden Reste kaltzeitlicher Faunen festgestellt, die auf Kälteperioden hinweisen. Der Bereich der unteren und, in geringerem Maße, der Bereich der mittleren Humuszone zeichnen sich durch die Anwesenheit von warmzeitlichen Faunenelementen aus (darunter ausgesprochene Waldarten), was auf einen mehr oder weniger hohen Grad an Wiederbewaldung schließen lässt. Es handelt sich dabei ausnahmslos um Waldarten, die sowohl in Laub- als auch in Nadelwaldbeständen auftreten können. Der Abschnitt zwischen unterer und mittlerer Humuszone und die obere Humuszone führen lediglich Steppen- und Waldsteppengesellschaften, die eng miteinander verzahnt sind. Der vorliegende Fossilbericht lässt sich gut mit den allgemein akzeptierten Vorstellungen über die Klimaentwicklung im frühen Würm vereinbaren, die sich aus Tiefsee- und Eisisotopenkurven ergeben haben. Zum gegenwärtigen Zeitpunkt wird eine Parallelisierung der unteren und mittleren Humuszone von Mainz-Weisenau mit den beiden bewaldeten norddeutschen Interstadialen Amersfoort/ Brörup und Odderade sowie den beiden St-Germain-Interstadialen in Ostfrankreich für wahrscheinlich gehalten. Für die Korrelation der oberen Humuszone werden verschiedene Möglichkeiten diskutiert.
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    Language: German
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  • 32
    Publication Date: 2022-08-05
    Description: Vorgestellt werden Untersuchungen zur holozänen Landschaftsentwicklung im Gebiet der Müritz, des größten Sees der Norddeutschen Tiefebene. Geomorphologische Untersuchungen zeigen für das Holozän bis zum Mittelalter eine im Wesentlichen aufwärts gerichtete Tendenz des Seespiegels (9500 BP: 57 m NN, 5400 BP: 61 m NN, AD 1100: 61 m NN, AD 1280: 62-63 m NN, nach AD 1300: 65 m NN, AD 1788: 63,5 m NN, heute: 62 m NN). Östlich des Sees wurden unter Wald große Flächen mit jungen anthropogenen Erosionsspuren nachgewiesen. Vier Pollendiagramme geben einen Überblick zur Vegetationsentwicklung auf verschiedenen Standorten und bei unterschiedlich starkem menschlichen Einfluß. Die bislang im Gebiet nachgewiesenen 401 archäologischen Fundplätze datieren überwiegend in das Neolithikum, die Bronzezeit und die Slawenzeit. Die Auswirkungen des Menschen auf den See und sein Umland sowie die Qualität der Befunde stehen im Mittelpunkt der Diskussion.
    Description: research
    Keywords: ddc:551.7
    Language: German
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  • 33
    Publication Date: 2022-08-05
    Description: Glaziale Sedimente und Formen der tropischen Anden enthalten Paläoklima-Archive. Für die Jüngere Dryaszeit (Younger Dryas = YD) besteht eine kontroverse Diskussion bezüglich der Gletschervorstöße. Im Gebiet des Papallacta-Passes (Ostkordilleren in Ecuador) wird ein Gletschervorstoß durch Till und Moränen dokumentiert. Die glazialen Sedimente werden unter- und überlagert von Tephrahorizonten, Torf und anderen Sedimenten, die reich an organischem Material sind. Radiokarbon-Altersbestimmungen werden somit möglich. 29 14C-Alter zu diesem Gletschervorstoß publizierten Clapperton et al. (1997); weitere 29 14C-Alter werden hier vorgestellt. Die Daten belegen sowohl feuchte (=Gletschervorstoß) als auch trockene (= Gletscherabschmelzen) Klimabedingungen während der Jüngeren Dryaszeit. Unter Berücksichtigung der kalibrierten 14C-Alter ergibt sich ein Gletschervorstoß in der zweiten Hälfte der Jüngeren Dryaszeit und zu Beginn des Holozäns. An dem Beispiel wird belegt, daß die Interpretation der 14C-datierten Jüngere Dryaszeitlichen Gletschervorstöße mit größter Sorgfalt vorgenommen werden muß.
    Description: research
    Keywords: ddc:551.7
    Language: German
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  • 34
    Publication Date: 2022-08-05
    Description: research
    Keywords: ddc:551.7
    Language: German
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  • 35
    Publication Date: 2022-08-05
    Description: research
    Keywords: ddc:551.7
    Language: German
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  • 36
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    Description: research
    Keywords: ddc:551.7
    Language: German
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  • 37
    Publication Date: 2022-08-05
    Description: research
    Keywords: ddc:551.7
    Language: German
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  • 38
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    Publication Date: 2022-08-05
    Description: research
    Keywords: ddc:551.7
    Language: German
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  • 39
    Publication Date: 2022-08-05
    Description: In der Nachbarschaft von Flüssen und größeren Bächen nimmt der Löß sehr häufig eine sandige Beschaffenheit an, in vielen Gebieten ist sogar die Sandkomponente in Form von verschieden starken Schichten (Sandbänder) eingeschaltet. Die vorliegende Arbeit beschäftigt sich in der Hauptsache mit der Lagerung der Sandbänder im vertikalen Profil und mit den Veränderungen in horizontaler Richtung. Auf Grund der allgemeinen Ausbildung und der Körnungsunterschiede des Lößes konnten westlich Königgrätz 4 Faziesbereiche unterschieden werden und zwar die Flugsand-, Bänder-, Übergangs- und Normalfazies. Die 4 Fazieszonen folgen von O nach W aufeinander. Die speziellen Untersuchungen an den Sandbändern führten zu folgenden Ergebnissen: 1. Die Abnahme des prozentualen Anteils der Gesamtmächtigkeit der Sandbänder am Löß erfolgt linear mit dem Logarithmus der Entfernung vom Auswehungsgebiet. 2. Die durchschnittliche Anzahl der Sandbänder je Meter Löß ändert sich mit der Zunahme der Entfernung vom Ursprungsgebiet, wie im einzelnen aus Abb. 10 hervorgeht. 3. Neben der Gesamtmächtigkeit und der Anzahl der Sandbänder wurde auch die Häufigkeit der verschiedenen Mächtigkeitsstufen ermittelt und graphisch aufgetragen (Abb. 11). Dabei ergab sich, daß in unmittelbarer Nähe des Auswehungsgebietes neben wenigen 9 und 10 cm mächtigen Bändern die 2 und 2,5 cm starken überwiegen. In einer Entfernung von etwa 300 m vom Flußufer dominieren die 1 und 1,5 cm starken. Weiter nach W nehmen aber nach und nach die dickeren Lagen wieder zu, so daß am Ende der Sandbänderfazies die 2 und 2,5 cm starken die häufigsten sind. Aus den mitgeteilten Ergebnissen und aus zahlreichen Körnungsanalysen wird geschlossen, daß sowohl die eingelagerten Sandschichten als auch der gößte Teil des Lößes äolischen Ursprungs sind. Sandlagen und Löß wurden durch östliche Winde aus dem breiten Tal der Elbe ausgeweht und auf die benachbarten Höhen transportiert. Dabei gelangte der in Form von Bändern abgelagerte Sand bis zu einer Entfernung von ca. 700 m. Die Kornfeinheit des Lößes nimmt nach W hin immer mehr zu. Weitere Beobachtungen an dem Bystrice- und Cidlina-Tal im W des Untersuchungsgebietes bestätigen die Annahme von der Auswehung des Lößes und der Sandschichten aus den Tälern durch Winde aus östlicher Richtung. Daß die allgemeine Lößverbreitung auch von der Breite der Täler abhängig ist, zeigt ein Blick auf die Karte (Abb. 1).
    Description: research
    Keywords: ddc:551.7
    Language: German
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  • 40
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    Publication Date: 2022-08-05
    Description: Der Rodderberg bei Bonn ist der nördlichste Teil des Osteifel-Vulkanfeldes aus dem Pleistozän. Seine mehrphasige Entstehungsgeschichte ist verzahnt mit den fluviatilen Sedimenten des Rheins und den äolischen Sedimenten aus den Eiszeiten. Die dort aufgeschlossenen Gesteine Basalt, Löß und vulkanthermisch beeinflusster Löß erlauben den Vergleich von Magnetisierungen von Materialien etwa gleichen Alters, aber unterschiedlicher Zusammensetzung und Geschichte. Die von der lokalen Erdmagnetfeld-Richtung deutlich abweichende flache Magnetisierungsrichtung der Basaltproben ist durch Blitzschlag verursacht worden und stellte sich als Beispiel von Blitzschlag-Magnetisierung heraus. Aus der Verteilung der Deklination der Magnetisierung konnte die Einschlagstelle der Blitze in etwa 5 m vom Probenprofil ermittelt werden. Eine aeromagnetische Vermessung des Rodderberges hat neue Hinweise zu seiner Struktur ergeben: Die Anomalie erstreckt sich von NNW nach SSE, der magnetisch wirksame Teil der Vulkanstruktur beschränkt sich auf den Bereich innerhalb des topographisch erkennbaren Kraters. Der umlaufende Schlacke-Aschewall ist magnetisch nicht erkennbar. Unterschiede der Anomalieform aus Messungen am Boden und in 35 m Höhe (Aeromagnetik) legen den Schluss nahe, dass die magnetisch wirksame Kraterstruktur einen flachgründigen Körper aus pyroklastischem Material anzeigt. Mit einigem Abstand darunter ist weiterer Basalt zu erwarten. Mit dem Rodderberg scheint uns die Natur einen Vulkan zu liefern, der am Beginn von phreatomagmatischen Erscheinungen geprägt war, dessen zweite Hälfte seiner lang währenden Genese aber die eines mehr klassischen Vulkans war.
    Description: research
    Keywords: ddc:551.7
    Language: German
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  • 41
    Publication Date: 2022-08-05
    Description: Geowissenschaftliche Untersuchungen bei Kallmünz in der südöstlichen Fränkischen Alb (Bayern) erbrachten paläobotanische Proben für Pollen- und Holzkohleanalyse. Die Auswertung gibt Hinweise auf die Vegetationszusammensetzung zu verschiedenen Zeiten des Holozäns. Intensive Landschaftsnutzung setzt spätestens in der Bronzezeit ein. In der römischen Periode und im Mittelalter können ausgeprägtere und großflächigere Eingriffe belegt werden. Für paläoökologische Forschung in Karstgebieten ist die Anwendung der Holzkohleanalyse von besonderem Nutzen, da palynologische Methoden aufgrund der Moorarmut nur begrenzt anwendbar sind.
    Description: research
    Keywords: ddc:551.7
    Language: German
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  • 42
    Publication Date: 2022-08-05
    Description: research
    Keywords: ddc:551.7
    Language: German
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  • 43
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    Publication Date: 2022-08-05
    Description: research
    Keywords: ddc:551.7
    Language: German
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  • 44
    Publication Date: 2022-08-08
    Description: research
    Keywords: ddc:551.7
    Language: German
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  • 45
    Publication Date: 2004-12-03
    Description: The objectives of this report was to develop a methodology to predict the time-dependent reliability (probability of failure) of brittle material components subjected to transient thermomechanical loading, taking into account the change in material response with time. This methodology for computing the transient reliability in ceramic components subjected to fluctuation thermomechanical loading was developed, assuming SCG (Slow Crack Growth) as the delayed mode of failure. It takes into account the effect of varying Weibull modulus and materials with time. It was also coded into a beta version of NASA's CARES/Life code, and an example demonstrating its viability was presented.
    Keywords: Aircraft Propulsion and Power
    Type: Fifth Annual Workshop on the Application of Probabilistic Methods for Gas Turbine Engines; 555-586; NASA/CP-2002-211682
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  • 46
    Publication Date: 2004-12-03
    Description: This viewgraph presentation provides information on the work done at NASA's Glenn Research Center on the ultra-efficient engine technology (UEET) program. The intent at the program's outset in 1998 was to establish a foundation for the next generation of aircraft engines for both commercial and military applications. A primary focus of this program was to be the development and utilization of technologies which would improve both subsonic and high-speed flight capabilities. Included in the presentation are details on the development of propulsion systems for varied types of aircraft, and results from attempts at reduction of emissions.
    Keywords: Aircraft Propulsion and Power
    Type: 2000 NASA Seal/Secondary Air System Workshop; Volume 1; 33-60; NASA/CP-2001-211208/VOL1
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  • 47
    Publication Date: 2011-08-23
    Description: This paper presents performance results for pulse detonation engines taking into account the effects of dissociation and recombination. The amount of sensible heat recovered through recombination in the PDE chamber and exhaust process was found to be significant. These results have an impact on the specific thrust, impulse and fuel consumption of the PDE.
    Keywords: Aircraft Propulsion and Power
    Type: 26th JANNAF Airbreathing Propulsion Subcommittee Meeting; Volume 1; 337-349; CPIA-Publ-713-Vol-1
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  • 48
    Publication Date: 2011-08-23
    Description: The total temperatures (enthalpies) required to ground-test air-breathing (aero-propulsion) engines at high Mach number flight conditions can be achieved in a number of ways. Among these are: 1. Heat exchangers, including pre-heated ceramic beds. 2. direct electrical heating, e.g., arc discharge and resistance heaters. 3. Compression heating. 4. Shock heating, and 5. In-stream combustion, with oxygen replenishment to match air content. Each method has distinct advantages, disadvantages and limitations. All have a common characteristic of being designed for intermittent flow, due to the extreme energy required for continuous operation at simulated Mach numbers above about 3. All also distort the composition of atmospheric air to some degree, due to the high temperatures that occur in the plenum section prior to expansion of the flow to simulated flight conditions. In the case of in-stream combustion, the resulting test medium is commonly referred to as "vitiated air", being composed of oxygen, nitrogen and some fraction of combustion products.
    Keywords: Aircraft Propulsion and Power
    Type: JANNAF 25th Airbreathing Propulsion Subcommittee, 37th Combustion Subcommittee and 1st Modeling and Simultation Subcommittee Joint Meeting; Volume 1; 243-271; CPIA-Publ-703-Vol-1
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  • 49
    Publication Date: 2013-08-31
    Description: In 1939, W. Weibull developed what is now commonly known as the "Weibull Distribution Function" primarily to determine the cumulative strength distribution of small sample sizes of elemental fracture specimens. In 1947, G. Lundberg and A. Palmgren, using the Weibull Distribution Function developed a probabilistic lifing protocol for ball and roller bearings. In 1987, E. V. Zaretsky using the Weibull Distribution Function modified the Lundberg and Palmgren approach to life prediction. His method incorporates the results of coupon fatigue testing to compute the life of elemental stress volumes of a complex machine element to predict system life and reliability. This paper examines the Zaretsky method to determine the probabilistic life and reliability of a model gas turbine disk using experimental data from coupon specimens. The predicted results are compared to experimental disk endurance data.
    Keywords: Aircraft Propulsion and Power
    Type: Fifth Annual Workshop on the Application of Probabilistic Methods for Gas Turbine Engines; 603-625; NASA/CP-2002-211682
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  • 50
    Publication Date: 2016-06-07
    Description: This report discusses the National Combustion Code (NCC). The NCC is an integrated system of codes for the design and analysis of combustion systems. The advanced features of the NCC meet designers' requirements for model accuracy and turn-around time. The fundamental features at the inception of the NCC were parallel processing and unstructured mesh. The design and performance of the NCC are discussed.
    Keywords: Aircraft Propulsion and Power
    Type: 2000 Numerical Propulsion System Simulation Review; 91-103; NASA/CP-2001-210673
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  • 51
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    Publication Date: 2016-06-07
    Description: This report provides an overview presentation of the 2000 NPSS (Numerical Propulsion System Simulation) Review and Planning Meeting. Topics include: 1) a background of the program; 2) 1999 Industry Feedback; 3) FY00 Status, including resource distribution and major accomplishments; 4) FY01 Major Milestones; and 5) Future direction for the program. Specifically, simulation environment/production software and NPSS CORBA Security Development are discussed.
    Keywords: Aircraft Propulsion and Power
    Type: 2000 Numerical Propulsion System: Simulation Review; 1-36; NASA/CP-2001-210673
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  • 52
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    In:  CASI
    Publication Date: 2016-06-07
    Description: This report outlines the GRC RBCC Concept for Multidisciplinary Analysis. The multidisciplinary coupling procedure is presented, along with technique validations and axisymmetric multidisciplinary inlet and structural results. The NPSS (Numerical Propulsion System Simulation) test bed developments and code parallelization are also presented. These include milestones and accomplishments, a discussion of running R4 fan application on the PII cluster as compared to other platforms, and the National Combustor Code speedup.
    Keywords: Aircraft Propulsion and Power
    Type: 2000 Numerical Propulsion System Simulation Review; 71-89; NASA/CP-2001210673
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  • 53
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    In:  CASI
    Publication Date: 2016-06-07
    Description: This report outlines the detailed simulation of Aircraft Turbofan Engine. The objectives were to develop a detailed flow model of a full turbofan engine that runs on parallel workstation clusters overnight and to develop an integrated system of codes for combustor design and analysis to enable significant reduction in design time and cost. The model will initially simulate the 3-D flow in the primary flow path including the flow and chemistry in the combustor, and ultimately result in a multidisciplinary model of the engine. The overnight 3-D simulation capability of the primary flow path in a complete engine will enable significant reduction in the design and development time of gas turbine engines. In addition, the NPSS (Numerical Propulsion System Simulation) multidisciplinary integration and analysis are discussed.
    Keywords: Aircraft Propulsion and Power
    Type: 2000 Numerical Propulsion System: Simulation Review; 37-58; NASA/CP-2001-210673
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  • 54
    Publication Date: 2016-06-07
    Description: This report outlines the Space Transportation Propulsion Systems for the NPSS (Numerical Propulsion System Simulation) program. Topics include: 1) a review of Engine/Inlet Coupling Work; 2) Background/Organization of Space Transportation Initiative; 3) Synergy between High Performance Computing and Communications Program (HPCCP) and Advanced Space Transportation Program (ASTP); 4) Status of Space Transportation Effort, including planned deliverables for FY01-FY06, FY00 accomplishments (HPCCP Funded) and FY01 Major Milestones (HPCCP and ASTP); and 5) a review current technical efforts, including a review of the Rocket-Based Combined-Cycle (RBCC), Scope of Work, RBCC Concept Aerodynamic Analysis and RBCC Concept Multidisciplinary Analysis.
    Keywords: Aircraft Propulsion and Power
    Type: 2000 Numerical Propulsion System Simulation Review; 59-69; NASA/CP-2001-210673
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  • 55
    Publication Date: 2013-08-29
    Description: Mass injection upstream of the tip of a high-speed axial compressor rotor is a stability enhancement approach known to be effective in suppressing small in tip-critical rotors. This process is examined in a transonic axial compressor rotor through experiments and time-averaged Navier-Stokes CFD simulations. Measurements and simulations for discrete injection are presented for a range of injection rates and distributions of injectors around the annulus. The simulations indicate that tip injection increases stability by unloading the rotor tip and that increasing injection velocity improves the effectiveness of tip injection. For the tested rotor, experimental results demonstrate that at 70 percent speed the stalling flow coefficient can be reduced by 30 percent using an injected mass- flow equivalent to 1 percent of the annulus flow. At design speed, the stalling flow coefficient was reduced by 6 percent using an injected mass-fiow equivalent to 2 percent of the annulus flow. The experiments show that stability enhancement is related to the mass-averaged axial velocity at the tip. For a given injected mass-flow, the mass-averaged axial velocity at the tip is increased by injecting flow over discrete portions of the circumference as opposed to full-annular injection. The implications of these results on the design of recirculating casing treatments and other methods to enhance stability will be discussed.
    Keywords: Aircraft Propulsion and Power
    Type: Transactions of the ASME; Volume 123; 14-23
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  • 56
    Publication Date: 2013-08-31
    Description: In an era of shrinking development budgets and resources, where there is also an emphasis on reducing the product development cycle, the role of system assessment, performed in the early stages of an engine development program, becomes very critical to the successful development of new aeropropulsion systems. A reliable system assessment not only helps to identify the best propulsion system concept among several candidates, it can also identify which technologies are worth pursuing. This is particularly important for advanced aeropropulsion technology development programs, which require an enormous amount of resources. In the current practice of deterministic, or point-design, approaches, the uncertainties of design variables are either unaccounted for or accounted for by safety factors. This could often result in an assessment with unknown and unquantifiable reliability. Consequently, it would fail to provide additional insight into the risks associated with the new technologies, which are often needed by decision makers to determine the feasibility and return-on-investment of a new aircraft engine. In this work, an alternative approach based on the probabilistic method was described for a comprehensive assessment of an aeropropulsion system. The statistical approach quantifies the design uncertainties inherent in a new aeropropulsion system and their influences on engine performance. Because of this, it enhances the reliability of a system assessment. A technical assessment of a wave-rotor-enhanced gas turbine engine was performed to demonstrate the methodology. The assessment used probability distributions to account for the uncertainties that occur in component efficiencies and flows and in mechanical design variables. The approach taken in this effort was to integrate the thermodynamic cycle analysis embedded in the computer code NEPP (NASA Engine Performance Program) and the engine weight analysis embedded in the computer code WATE (Weight Analysis of Turbine Engines) with the fast probability integration technique (FPI). FPI was developed by Southwest Research Institute under contract with the NASA Glenn Research Center. The results were plotted in the form of cumulative distribution functions and sensitivity analyses and were compared with results from the traditional deterministic approach. The comparison showed that the probabilistic approach provides a more realistic and systematic way to assess an aeropropulsion system. The current work addressed the application of the probabilistic approach to assess specific fuel consumption, engine thrust, and weight. Similarly, the approach can be used to assess other aspects of aeropropulsion system performance, such as cost, acoustic noise, and emissions. Additional information is included in the original extended abstract.
    Keywords: Aircraft Propulsion and Power
    Type: Fifth Annual Workshop on the Application of Probabilistic Methods for Gas Turbine Engines; 139-164; NASA/CP-2002-211682
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  • 57
    Publication Date: 2011-08-23
    Description: Aircraft fan and compressor blade leading edges suffer from atmospheric particulate erosion that reduces aerodynamic performance. Recontouring the blade leading edge region can restore blade performance. This process typically results in blades of varying chord length. The question therefore arises as to whether performance of refurbished fans and compressors could be further improved if blades of varying chord length are installed into the disk in a certain order. To investigate this issue the aerodynamic performance of a transonic compressor rotor operating with blades of varying chord length was measured in back-to-back compressor test rig entries. One half of the rotor blades were the full nominal chord length while the remaining half of the blades were cut back at the leading edge to 95% of chord length and recontoured. The rotor aerodynamic performance was measured at 100, 80, and 60% of design speed for three blade installation configurations: nominal-chord blades in half of the disk and short-chord blades in half of the disk; four alternating quadrants of nominal-chord and short-chord blades; nominal-chord and short-chord blades alternating around the disk. No significant difference in performance was found between configurations, indicating that blade chord variation is not important to aerodynamic performance above the stall chord limit if leading edges have the same shape. The stall chord limit for most civil aviation turbofan engines is between 94-96% of nominal (new) blade chord.
    Keywords: Aircraft Propulsion and Power
    Type: Journal of Turbomachinery; Volume 24; 351-357
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  • 58
    Publication Date: 2011-08-23
    Description: This paper presents progress on the development of a generic component level model of a turbofan engine simulation, with a digital controller, in an advanced graphical simulation environment. The goal of this effort is to develop and demonstrate a flexible simulation platform for future research in propulsion system control and diagnostic technology. A FORTRAN-based model of a modem, high performance, military-type turbofan engine is being used to validate the platform development. The implementation process required the development of various innovative procedures, which are discussed in the paper. Open-loop and closed-loop comparisons are made between the two simulations. Future enhancements that are to be made to the modular engine simulation are summarized.
    Keywords: Aircraft Propulsion and Power
    Type: 26th JANNAF Airbreathing Propulsion Subcommittee Meeting; Volume 1; 249-257; CPIA-Publ-713-Vol-1
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  • 59
    Publication Date: 2013-08-29
    Description: Two methods are commonly used to control the secondary/separated flows (and associated losses) in supersonic turbines: endwall contouring and airfoil stacking. In the current investigation the flow path between the first-stage vanes and rotors, and the stacking of the first-stage vanes were varied in an effort to improve turbine performance. The geometric variations have been studied by performing a series of unsteady three-dimensional numerical simulations for the two-stage turbine.
    Keywords: Aircraft Propulsion and Power
    Type: 2002 AIAA Aerospace Sciences Meeting; Unknown
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  • 60
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    Publication Date: 2016-06-07
    Description: The purpose of this presentation is to show flight demonstrations, complete preflight ground tests, and the assembling of the first QRT 4 engine.
    Keywords: Aircraft Propulsion and Power
    Type: 1999 NASA Seal/Secondary Air System Workshop; Volume 1; 61-78; NASA/CP-2000-210472/VOL1
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  • 61
    Publication Date: 2018-06-06
    Description: Physical constraints of any real system can have a drastic effect on its performance. Some of the more recognized constraints are actuator and sensor saturation and bandwidth, power consumption, sampling rate (sensor and control-loop) and computation limits. These constraints can degrade system s performance, such as settling time, overshoot, rising time, and stability margins. In order to address these issues, researchers have investigated the use of robust and nonlinear controllers that can incorporate uncertainty and constraints into a controller design. For instance, uncertainties can be addressed in the synthesis model used in such algorithms as H(sub infinity), or mu. There is a significant amount of literature addressing this type of problem. However, there is one constraint that has not often been considered; that is, actuator authority resolution. In this work, thruster resolution and controller schemes to compensate for this effect are investigated for position and attitude control of a Low Earth Orbit formation flight system In many academic problems, actuators are assumed to have infinite resolution. In real system applications, such as formation flight systems, the system actuators will not have infinite resolution. High-precision formation flying requires the relative position and the relative attitude to be controlled on the order of millimeters and arc-seconds, respectively. Therefore, the minimum force resolution is a significant concern in this application. Without the sufficient actuator resolution, the system may be unable to attain the required pointing and position precision control. Furthermore, fuel may be wasted due to high-frequency chattering phenomena when attempting to provide a fine control with inadequate actuators. To address this issue, a Sliding Mode Controller is developed along with the boundary Layer Control to provide the best control resolution constraints. A Genetic algorithm is used to optimize the controller parameters according to the states error and fuel consumption criterion. The tradeoffs and effects of the minimum force limitation on performance are studied and compared to the case without the limitation. Furthermore, two methods are proposed to reduce chattering and improve precision.
    Keywords: Aircraft Propulsion and Power
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  • 62
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2018-06-05
    Description: The Ultra-Efficient Engine Technology (UEET) Program includes seven key projects that work with industry to develop and hand off revolutionary propulsion technologies that will enable future-generation vehicles over a wide range of flight speeds. A new program office, the Ultra-Efficient Engine Technology (UEET) Program Office, was formed at the NASA Glenn Research Center to manage an important National propulsion program for NASA. The Glenn-managed UEET Program, which began on October 1, 1999, includes participation from three other NASA centers (Ames, Goddard, and Langley), as well as five engine companies (GE Aircraft Engines, Pratt & Whitney, Honeywell, Allison/Rolls Royce, and Williams International) and two airplane manufacturers (the Boeing Company and Lockheed Martin Corporation). This 6-year, nearly $300 million program will address local air-quality concerns by developing technologies to significantly reduce nitrogen oxide (NOx) emissions. In addition, it will provide critical propulsion technologies to dramatically increase performance as measured in fuel burn reduction that will enable reductions of carbon dioxide (CO2) emissions. This is necessary to address the potential climate impact of long-term aviation growth.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2000; NASA/TM-2001-210605
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  • 63
    Publication Date: 2018-06-05
    Description: Closed-loop flow control was successfully demonstrated on the surface of stator vanes in NASA Glenn Research Center's Low-Speed Axial Compressor (LSAC) facility. This facility provides a flow field that accurately duplicates the aerodynamics of modern highly loaded compressors. Closed-loop active flow control uses sensors and actuators embedded within engine components to dynamically alter the internal flow path during off-nominal operation in order to optimize engine performance and maintain stable operation.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2003; NASA/TM-2004-212729
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  • 64
    Publication Date: 2018-06-05
    Description: The goal of the Autonomous Propulsion System Technology (APST) project is to reduce pilot workload under both normal and anomalous conditions. Ongoing work under APST develops and leverages technologies that provide autonomous engine monitoring, diagnosing, and controller adaptation functions, resulting in an integrated suite of algorithms that maintain the propulsion system's performance and safety throughout its life. Engine-to-engine performance variation occurs among new engines because of manufacturing tolerances and assembly practices. As an engine wears, the performance changes as operability limits are reached. In addition to these normal phenomena, other unanticipated events such as sensor failures, bird ingestion, or component faults may occur, affecting pilot workload as well as compromising safety. APST will adapt the controller as necessary to achieve optimal performance for a normal aging engine, and the safety net of APST algorithms will examine and interpret data from a variety of onboard sources to detect, isolate, and if possible, accommodate faults. Situations that cannot be accommodated within the faulted engine itself will be referred to a higher level vehicle management system. This system will have the authority to redistribute the faulted engine's functionality among other engines, or to replan the mission based on this new engine health information. Work is currently underway in the areas of adaptive control to compensate for engine degradation due to aging, data fusion for diagnostics and prognostics of specific sensor and component faults, and foreign object ingestion detection. In addition, a framework is being defined for integrating all the components of APST into a unified system. A multivariable, adaptive, multimode control algorithm has been developed that accommodates degradation-induced thrust disturbances during throttle transients. The baseline controller of the engine model currently being investigated has multiple control modes that are selected according to some performance or operational criteria. As the engine degrades, parameters shift from their nominal values. Thus, when a new control mode is swapped in, a variable that is being brought under control might have an excessive initial error. The new adaptive algorithm adjusts the controller gains on the basis of the level of degradation to minimize the disruptive influence of the large error on other variables and to recover the desired thrust response.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2003; NASA/TM-2004-212729
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  • 65
    Publication Date: 2018-06-05
    Description: Typical installed separate-flow exhaust nozzle system. The jet noise from modern turbofan engines is a major contributor to the overall noise from commercial aircraft. Many of these engines use separate nozzles for exhausting core and fan streams. As a part of NASA s Advanced Subsonic Technology (AST) program, the NASA Glenn Research Center at Lewis Field led an experimental investigation using model-scale nozzles in Glenn s Aero-Acoustic Propulsion Laboratory. The goal of the investigation was to develop technology for reducing the jet noise by 3 EPNdB. Teams of engineers from Glenn, the NASA Langley Research Center, Pratt & Whitney, United Technologies Research Corporation, the Boeing Company, GE Aircraft Engines, Allison Engine Company, and Aero Systems Engineering contributed to the planning and implementation of the test.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 1999; NASA/TM-2000-209639
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  • 66
    Publication Date: 2018-06-05
    Description: The NASA Glenn Research Center is working with the aeronautics industry to develop highly fuel-efficient and environmentally friendly gas turbine combustor technology. This effort includes testing new hardware designs at conditions that simulate the high-temperature, high-pressure environment expected in the next-generation of high-performance engines. Glenn has the only facilities in which such tests can be performed. One aspect of these tests is the use of nonintrusive optical and laser diagnostics to measure combustion species concentration, fuel/air ratio, fuel drop size, and velocity, and to visualize the fuel injector spray pattern and some combustion species distributions. These data not only help designers to determine the efficacy of specific designs, but provide a database for computer modelers and enhance our understanding of the many processes that take place within a combustor. Until recently, we lacked one critical capability, the ability to measure temperature. This article summarizes our latest developments in that area. Recently, we demonstrated the first-ever use of spontaneous Raman scattering to measure combustion temperatures within the Advanced Subsonics Combustion Rig (ASCR) sector rig. We also established the highest rig pressure ever achieved for a continuous-flow combustor facility, 54.4 bar. The ASCR facility can provide operating pressures from 1 to 60 bar (60 atm). This photograph shows the Raman system setup next to the ASCR rig. The test was performed using a NASA-concept fuel injector and Jet-A fuel over a range of air inlet temperatures, pressures, and fuel/air ratios.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2001; NASA/TM-2002-211333
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  • 67
    Publication Date: 2018-06-05
    Description: The slides review computational requirements for nozzle exhaust flow and noise calculations and the current numerical method, validation of prefactored compact scheme on CAA benchmark problems, a curvilinear grid performance test of gust response of a Joukowski airfoil, airfoil surface RMS pressure distribution and far field noise radiation results for Joukowski airfoil in a vortical gust, boundary distance study for Joukowski airfoil problem, and performance of ICOMP parallel Macintosh cluster.
    Keywords: Aircraft Propulsion and Power
    Type: Proceedings of the Jet Noise Workshop; 951-965; NASA/CP-2001-211152
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  • 68
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2018-06-06
    Description: A Hele-Shaw flow apparatus constructed at Michigan State University (MSU) produces conditions that reduce influences of buoyancy-driven flows. In addition, in the MSU Hele-Shaw apparatus it is possible to adjust the heat losses from the fuel sample (0.001 in. thick cellulose) and the flow speed of the approaching oxidizer flow (air) so that the "flamelet regime of flame spread" is entered. In this regime various features of the flame-to-smolder (and vice versa) transition can be studied. For the relatively wide (approx. 17.5 cm) and long (approx. 20 cm) samples used, approximately ten flamelets existed at all times. The flamelet behavior was studied mechanistically and statistically. A heat transfer analysis of the dominant heat transfer mechanisms was conducted. Results indicate that radiation and conduction processes are important, and that a simple 1-D model using the Broido-Shafizadeh model for cellulose decomposition chemistry can describe aspects of the flamelet spread process. Introduction
    Keywords: Aircraft Propulsion and Power
    Type: Seventh International Workshop on Microgravity Combustion and Chemically Reacting Systems; 29-32; NASA/CP-2003-212376/REV1
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  • 69
    Publication Date: 2018-06-06
    Description: Combustion experiments using arrays of droplets seek to provide a link between single droplet combustion phenomena and the behavior of complex spray combustion systems. Both single droplet and droplet array studies have been conducted in microgravity to better isolate the droplet interaction phenomena and eliminate or reduce the effects of buoyancy-induced convection. In most experiments involving droplet arrays, the droplets are supported on fibers to keep them stationary and close together before the combustion event. The presence of the fiber, however, disturbs the combustion process by introducing a source of heat transfer and asymmetry into the configuration. As the number of drops in a droplet array increases, supporting the drops on fibers becomes less practical because of the cumulative effect of the fibers on the combustion process. To eliminate the effect of the fiber, several researchers have conducted microgravity experiments using unsupported droplets. Jackson and Avedisian investigated single, unsupported drops while Nomura et al. studied droplet clouds formed by a condensation technique. The overall objective of this research is to extend the study of unsupported drops by investigating the combustion of well-characterized drop clusters in a microgravity environment. Direct experimental observations and measurements of the combustion of droplet clusters would provide unique experimental data for the verification and improvement of spray combustion models. In this work, the formation of drop clusters is precisely controlled using an acoustic levitation system so that dilute, as well as dense clusters can be created and stabilized before combustion in microgravity is begun. While the low-gravity test facility is being completed, tests have been conducted in 1-g to characterize the effect of the acoustic field on the vaporization of single and multiple droplets. This is important because in the combustion experiment, the droplets will be formed and levitated prior to ignition. Therefore, the droplets will begin to vaporize in the acoustic field thus forming the "initial conditions" for the combustion process. Understanding droplet vaporization in the acoustic field of this levitator is a necessary step that will help to interpret the experimental results obtained in low-gravity.
    Keywords: Aircraft Propulsion and Power
    Type: Seventh International Workshop on Microgravity Combustion and Chemically Reacting Systems; 5-8; NASA/CP-2003-212376-REV1
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  • 70
    Publication Date: 2018-06-06
    Description: A viewgraph presentation on the concept of compliant casing for transonic axial compressors is shown. The topics include: 1) Concept for compliant casing; 2) Rig and facility details; 3) Experimental results; and 4) Numerical results.
    Keywords: Aircraft Propulsion and Power
    Type: 2002 NASA Seal/Secondary Air System Workshop; Volume 1; 163-170; NASA/CP-2003-212458/VOL1
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  • 71
    Publication Date: 2018-06-06
    Description: Model the interactions between the structural dynamics and the performance dynamics of a gas turbine engine. Generally these two aspects are considered separate, unrelated phenomena and are studied independently. For diagnostic purposes, it is desirable to bring together as much information as possible, and that involves understanding how performance is affected by structural dynamics (if it is) and vice versa. This can involve the relationship between thrust response and the excitation of structural modes, for instance. The job will involve investigating and characterizing these dynamical relationships, generating a model that incorporates them, and suggesting and/or developing diagnostic and prognostic techniques that can be incorporated in a data fusion system. If no coupling is found, at the least a vibration model should be generated that can be used for diagnostics and prognostics related to blade loss, for instance.
    Keywords: Aircraft Propulsion and Power
    Type: 2003 NASA Faculty Fellowship Program at Glenn Research Center; 64-67
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  • 72
    Publication Date: 2018-06-05
    Description: The Stirling Radioisotope Generator (SRG) is currently being developed by Lockheed Martin Astronautics (Valley Forge, PA) under contract to the Department of Energy (Germantown, MD). In support of this project, the NASA Glenn Research Center has established a near-term technology effort to provide some of the critical data to ensure a successful transition to flight for what will be the first dynamic power system to be used in space. The generator will be a high-efficiency electric power source for potential use on NASA space science missions. The generator will be able to operate in the vacuum of deep space or in an atmosphere such as on the surface of Mars. High system efficiency is obtained through the use of free-piston Stirling power-conversion technology. The power output of the generator will be greater than 100 W at the beginning of life, with the slow decline in power being largely due to decay of the plutonium heat source. Previously, Glenn's supporting technology efforts focused only on the most critical technical issues.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2003; NASA/TM-2004-212729
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  • 73
    Publication Date: 2018-06-05
    Description: The NASA Glenn Research Center at Lewis Field develops new technologies to increase the fuel efficiency of aircraft engines, improve the safety of engine operation, reduce emissions, and reduce engine noise. With the development of new designs for fans, compressors, and turbines to achieve these goals, the basic aeroelastic requirements are that there should be no flutter (self-excited vibrations) or high resonant blade stresses (due to forced response) in the operating regime. Therefore, an accurate prediction and analysis capability is required to verify the aeroelastic soundness of the designs. Such a three-dimensional viscous propulsion aeroelastic analysis capability has been developed at Glenn with support from the Advanced Subsonic Technology (AST) program. This newly developed aeroelastic analysis capability is based on TURBO, a threedimensional unsteady aerodynamic Reynolds-averaged Navier-Stokes turbomachinery code developed previously under a grant from Glenn. TURBO can model the viscous flow effects that play an important role in certain aeroelastic problems such as flutter with flow separation, flutter at high loading conditions near the stall line (stall flutter), flutter in the presence of shock and boundary-layer interaction, and forced response due to wakes and shock impingement. In aeroelastic analysis, the structural dynamics representation of the blades is based on normal modes. A finite-element analysis code is used to calculate these in-vacuum vibration modes and the associated natural frequencies. In an aeroelastic analysis using the TURBO code, flutter and forced response are modeled as being uncoupled. To calculate if a blade row will flutter, one prescribes the motion of the blade to be a harmonic vibration in a specified in-vacuum normal mode. An aeroelastic analysis preprocessor is used to generate the displacement field required for the analysis. The work done by aerodynamic forces on the vibrating blade during a cycle of vibration is calculated. If this work is positive, the blade is dynamically unstable, since it will extract energy from the flow, leading to an increase in the blade s oscillation amplitude. The forced-response excitations on a blade row are calculated by modeling the flow through two adjacent blade rows using the TURBO code. The blades are assumed to be rigid. As an option, a single blade row can be modeled with the upstream blade row influence represented by a time-varying disturbance (gust) at the inlet boundary. The unsteady forces on a blade row from such analyses are used in a structural analysis along with the blade structural dynamics characteristics and aerodynamic damping associated with blade vibration to calculate the resulting dynamic stresses on the blade.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 1999; NASA/TM-2000-209639
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  • 74
    Publication Date: 2018-06-05
    Description: The tip clearance flows of transonic compressor rotors have a significant impact on rotor and stage performance. Although numerical simulations of these flows are quite sophisticated, they are seldom verified through rigorous comparisons of numerical and measured data because, in high-speed machines, measurements acquired in sufficient detail to be useful are rare. Researchers at the NASA Glenn Research Center at Lewis Field compared measured tip clearance flow details (e.g., trajectory and radial extent) of the NASA Rotor 35 with results obtained from a numerical simulation. Previous investigations had focused on capturing the detailed development of the jetlike flow leaking through the clearance gap between the rotating blade tip and the stationary compressor shroud. However, we discovered that the simulation accuracy depends primarily on capturing the detailed development of a wall-bounded shear layer formed by the relative motion between the leakage jet and the shroud.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 1999; NASA/TM-2000-209639
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  • 75
    Publication Date: 2018-06-05
    Description: Higher operating temperatures increase the efficiency of aircraft gas turbine engines, but can also degrade internal components. High-pressure turbine blades just downstream of the combustor are particularly susceptible to overheating. Computational fluid dynamics (CFD) computer programs can predict the flow around the blades so that potential hot spots can be identified and appropriate cooling schemes can be designed. Various blade and cooling schemes can be examined computationally before any hardware is built, thus saving time and effort. Often though, the accuracy of these programs has been found to be inadequate for predicting heat transfer. Code and model developers need highly detailed aerodynamic and heat transfer data to validate and improve their analyses. The Transonic Turbine Blade Cascade was built at the NASA Glenn Research Center at Lewis Field to help satisfy the need for this type of data.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 1999; NASA/TM-2000-209639
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  • 76
    Publication Date: 2018-06-05
    Description: The potential benefits of nonlinear engine control technology applied to a General Electric T700 helicopter engine were investigated. This technology is being developed by the U.S. Navy SPAWAR Systems Center for a variety of applications. When used as a means of active stability control, nonlinear engine control technology uses sensors and small amounts of injected air to allow compressors to operate with reduced stall margin, which can improve engine pressure ratio. The focus of this study was to determine the best achievable reduction in fuel consumption for the T700 turboshaft engine. A customer deck (computer code) was provided by General Electric to calculate the T700 engine performance, and the NASA Glenn Research Center used this code to perform the analysis. The results showed a 2- to 5-percent reduction in brake specific fuel consumption (BSFC) at the three Sikorsky H-60 helicopter operating points of cruise, loiter, and hover.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2003; NASA/TM-2004-212729
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  • 77
    Publication Date: 2018-06-05
    Description: Rapidly emerging fuel-cell-power technologies may be used to launch a new revolution of electric propulsion systems for light aircraft. Future small electric airplanes using fuel cell technologies hold the promise of high reliability, low maintenance, low noise, and - with the exception of water vapor - zero emissions. An analytical feasibility and performance assessment was conducted by NASA Glenn Research Center's Airbreathing Systems Analysis Office of a fuel-cell-powered, propeller-driven, small electric airplane based on a model of the MCR-01 two-place kitplane (Dyn'Aero, Darois, France). This assessment was conducted in parallel with an ongoing effort by the Advanced Technology Products Corporation and the Foundation for Advancing Science and Technology Education. Their project - partially funded by a NASA grant - is to design, build, and fly the first manned, continuously propelled, nongliding electric airplane. In our study, an analytical performance model of a proton exchange membrane (PEM) fuel cell propulsion system was developed and applied to a notional, two-place light airplane modeled after the MCR-01 kitplane. The PEM fuel cell stack was fed pure hydrogen fuel and humidified ambient air via a small automotive centrifugal supercharger. The fuel cell performance models were based on chemical reaction analyses calibrated with published data from the fledgling U.S. automotive fuel cell industry. Electric propeller motors, rated at two shaft power levels in separate assessments, were used to directly drive a two-bladed, variable-pitch propeller. Fuel sources considered were compressed hydrogen gas and cryogenic liquid hydrogen. Both of these fuel sources provided pure, contaminant-free hydrogen for the PEM cells.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2003; NASA/TM-2004-212729
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  • 78
    Publication Date: 2018-06-02
    Description: Two experiments were conducted, using sound quality engineering practices, to determine the subjective effectiveness of hypothetical active noise control systems in a range of propeller aircraft. The two tests differed by the type of judgments made by the subjects: pair comparisons in the first test and numerical category scaling in the second. Although the results of the two tests were in general agreement that the hypothetical active control measures improved the interior noise environments, the pair comparison method appears to be more sensitive to subtle changes in the characteristics of the sounds which are related to passenger preference.
    Keywords: Aircraft Propulsion and Power
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  • 79
    Publication Date: 2018-06-02
    Description: The primary objective of this research program is to develop vibration analysis tools, design tools, and design strategies to significantly improve the safety and robustness of turbine engine rotors. Bladed disks in turbine engines always feature small, random blade-to-blade differences, or mistuning. Mistuning can lead to a dramatic increase in blade forced-response amplitudes and stresses. Ultimately, this results in high-cycle fatigue, which is a major safety and cost concern. In this research program, the necessary steps will be taken to transform a state-of-the-art vibration analysis tool, the Turbo-Reduce forced-response prediction code, into an effective design tool by enhancing and extending the underlying modeling and analysis methods. Furthermore, novel techniques will be developed to assess the safety of a given design. In particular, a procedure will be established for using eigenfrequency curve veerings to identify "danger zones" in the operating conditions--ranges of rotational speeds and engine orders in which there is a great risk that the rotor blades will suffer high stresses. This work also will aid statistical studies of the forced response by reducing the necessary number of simulations. Finally, new strategies for improving the design of rotors will be pursued. Several methods will be investigated, including the use of intentional mistuning patterns to mitigate the harmful effects of random mistuning, and the modification of disk stiffness to avoid reaching critical values of interblade coupling in the desired operating range. Recent research progress is summarized in the following paragraphs. First, significant progress was made in the development of the component mode mistuning (CMM) and static mode compensation (SMC) methods for reduced-order modeling of mistuned bladed disks (see the following figure). The CMM method has been formalized and extended to allow a general treatment of mistuning. In addition, CMM allows individual mode mistuning, which accounts for the realistic effects of local variations in blade properties that lead to different mistuning values for different mode types (e.g., mistuning of the first torsion mode versus the second flexural mode). The accuracy and efficiency of the CMM method and the corresponding Turbo-Reduce code were validated for an example finite element model of a bladed disk.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2003; NASA/TM-2004-212729
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  • 80
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2018-06-02
    Description: Technology for pollution-free "electric flight" is being evaluated in a number of NASA Glenn Research Center programs. One approach is to drive propulsive fans or propellers with electric motors powered by fuel cells running on hydrogen. For large transport aircraft, conventional electric motors are far too heavy to be feasible. However, since hydrogen fuel would almost surely be carried as liquid, a propulsive electric motor could be cooled to near liquid hydrogen temperature (-423 F) by using the fuel for cooling before it goes to the fuel cells. Motor windings could be either superconducting or high purity normal copper or aluminum. The electrical resistance of pure metals can drop to 1/100th or less of their room-temperature resistance at liquid hydrogen temperature. In either case, super or normal, much higher current density is possible in motor windings. This leads to more compact motors that are projected to produce 20 hp/lb or more in large sizes, in comparison to on the order of 2 hp/lb for large conventional motors. High power density is the major goal. To support cryogenic motor development, we have designed and built in-house a small motor (7-in. outside diameter) for operation in liquid nitrogen.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2003; NASA/TM-2004-212729
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  • 81
    Publication Date: 2018-06-02
    Description: Modern engineering design practices are tending more toward the treatment of design parameters as random variables as opposed to fixed, or deterministic, values. The probabilistic design approach attempts to account for the uncertainty in design parameters by representing them as a distribution of values rather than as a single value. The motivations for this effort include preventing excessive overdesign as well as assessing and assuring reliability, both of which are important for aerospace applications. However, the determination of the probability distribution is a fundamental problem in reliability analysis. A random variable is often defined by the parameters of the theoretical distribution function that gives the best fit to experimental data. In many cases the distribution must be assumed from very limited information or data. Often the types of information that are available or reasonably estimated are the minimum, maximum, and most likely values of the design parameter. For these situations the beta distribution model is very convenient because the parameters that define the distribution can be easily determined from these three pieces of information. Widely used in the field of operations research, the beta model is very flexible and is also useful for estimating the mean and standard deviation of a random variable given only the aforementioned three values. However, an assumption is required to determine the four parameters of the beta distribution from only these three pieces of information (some of the more common distributions, like the normal, lognormal, gamma, and Weibull distributions, have two or three parameters). The conventional method assumes that the standard deviation is a certain fraction of the range. The beta parameters are then determined by solving a set of equations simultaneously. A new method developed in-house at the NASA Glenn Research Center assumes a value for one of the beta shape parameters based on an analogy with the normal distribution (ref.1). This new approach allows for a very simple and direct algebraic solution without restricting the standard deviation. The beta parameters obtained by the new method are comparable to the conventional method (and identical when the distribution is symmetrical). However, the proposed method generally produces a less peaked distribution with a slightly larger standard deviation (up to 7 percent) than the conventional method in cases where the distribution is asymmetric or skewed. The beta distribution model has now been implemented into the Fast Probability Integration (FPI) module used in the NESSUS computer code for probabilistic analyses of structures (ref. 2).
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2003; NASA/TM-2004-212729
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  • 82
    Publication Date: 2018-06-02
    Description: Despite efforts in the search for alternative means of energy, combustion still remains the key source. Most propulsion systems primarily use combustion for their needed thrust. Associated with these propulsion systems are the high-velocity hot exhaust gases produced as the byproducts of combustion. These exhaust products often apply uneven high temperature and pressure over the surfaces of the appended structures exposed to them. If the applied pressure and temperature exceed the design criteria of the surfaces of these structures, they will not be able to protect the underlying structures, resulting in the failure of the vehicle mission. An understanding of the flow field associated with hot exhaust jets and the interactions of these jets with the structures in their path is critical not only from the design point of view but for the validation of the materials and manufacturing processes involved in constructing the materials from which the structures in the path of these jets are made. The hot exhaust gases often flow at supersonic speeds, and as a result, various incident and reflected shock features are present. These shock structures induce abrupt changes in the pressure and temperature distribution that need to be considered. In addition, the jet flow creates a gaseous plume that can easily be traced from large distances. To study the flow field associated with the supersonic gases induced by a rocket engine, its interaction with the surrounding surfaces, and its effects on the strength and durability of the materials exposed to it, NASA Glenn Research Center s Combustion Branch teamed with the Ceramics Branch to provide testing and analytical support. The experimental work included the full range of heat flux environments that the rocket engine can produce over a flat specimen. Chamber pressures were varied from 130 to 500 psia and oxidizer-to-fuel ratios (o/f) were varied from 1.3 to 7.5.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2003; NASA/TM-2004-212729
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  • 83
    Publication Date: 2018-06-02
    Description: Modern fan designs have blades with forward sweep; a lean, thin cross section; and a wide chord to improve performance and reduce noise. These geometric features coupled with the presence of a shock wave can lead to flutter instability. Flutter is a self-excited dynamic instability arising because of fluid-structure interaction, which causes the energy from the surrounding fluid to be extracted by the vibrating structure. An in-flight occurrence of flutter could be catastrophic and is a significant design issue for rotor blades in gas turbines. Understanding the flutter behavior and the influence of flow features on flutter will lead to a better and safer design. An aeroelastic analysis code, TURBO, has been developed and validated for flutter calculations at the NASA Glenn Research Center. The code has been used to understand the occurrence of flutter in a forward-swept fan design. The forward-swept fan, which consists of 22 inserted blades, encountered flutter during wind tunnel tests at part speed conditions.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2002; NASA/TM-2003-211990
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  • 84
    Publication Date: 2018-06-02
    Description: This work is motivated by the need to accurately predict heat transfer in turbomachinery. For efficient gas turbine operation, flow temperatures in the hot gas path exceed acceptable metal temperatures in many regions of the engine. So that the integrity of the parts can be maintained for an acceptable engine life, the parts must be cooled. Efficient cooling schemes require accurate heat transfer prediction to minimize regions that are overcooled and, even more importantly, to ensure adequate cooling in high-heat-flux regions.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2002; NASA/TM-2003-211990
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  • 85
    Publication Date: 2018-06-02
    Description: Future aeropropulsion gas turbine engines must be affordable in addition to being energy efficient and environmentally benign. Progress in aerodynamic design capability is required not only to maximize the specific thrust of next-generation engines without sacrificing fuel consumption, but also to reduce parts count by increasing the aerodynamic loading of the compression system. To meet future compressor requirements, the NASA Glenn Research Center is investigating advanced aerodynamic design concepts that will lead to more compact, higher efficiency, and wider operability configurations than are currently in operation.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2002; NASA/TM-2003-211990
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  • 86
    Publication Date: 2018-06-02
    Description: Forced response, or resonant vibrations, in turbomachinery components can cause blades to crack or fail because of the large vibratory blade stresses and subsequent high-cycle fatigue. Forced-response vibrations occur when turbomachinery blades are subjected to periodic excitation at a frequency close to their natural frequency. Rotor blades in a turbine are constantly subjected to periodic excitations when they pass through the spatially nonuniform flowfield created by upstream vanes. Accurate numerical prediction of the unsteady aerodynamics phenomena that cause forced-response vibrations can lead to an improved understanding of the problem and offer potential approaches to reduce or eliminate specific forced-response problems. The objective of the current work was to validate an unsteady aerodynamics code (named TURBO) for the modeling of the unsteady blade row interactions that can cause forced response vibrations. The three-dimensional, unsteady, multi-blade-row, Reynolds-averaged Navier-Stokes turbomachinery code named TURBO was used to model a high-pressure turbine stage for which benchmark data were recently acquired under a NASA contract by researchers at the Ohio State University. The test article was an initial design for a high-pressure turbine stage that experienced forced-response vibrations which were eliminated by increasing the axial gap. The data, acquired in a short duration or shock tunnel test facility, included unsteady blade surface pressures and vibratory strains.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2002; NASA/TM-2003-211990
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  • 87
    Publication Date: 2018-06-02
    Description: The NASA Glenn Research Center was the major contributor of 2-kW-class ion thruster technology to the Deep Space 1 mission, which was successfully completed in early 2002. Recently, NASA s Office of Space Science awarded approximately $21 million to Glenn to develop higher power xenon ion propulsion systems for large flagship missions such as outer planet explorers and sample return missions. The project, referred to as NASA's Evolutionary Xenon Thruster (NEXT), is a logical follow-on to the ion propulsion system demonstrated on Deep Space 1. The propulsion system power level for NEXT is expected to be as high as 25 kW, incorporating multiple ion thrusters, each capable of being throttled over a 1- to 6-kW power range. To date, engineering model thrusters have been developed, and performance and plume diagnostics are now being documented. The project team-Glenn, the Jet Propulsion Laboratory, General Dynamics, Boeing Electron Dynamic Devices, the Applied Physics Laboratory, the University of Michigan, and Colorado State University-is in the process of developing hardware for a ground demonstration of the NEXT propulsion system, which comprises a xenon feed system, controllers, multiple thrusters, and power processors. The development program also will include life assessments by tests and analyses, single-string tests of ion thrusters and power systems, and finally, multistring thruster system tests in calendar year 2005. In addition, NASA's Office of Space Science selected Glenn to lead the development of a 25-kW xenon thruster to enable NASA to conduct future missions to the outer planets of Jupiter and beyond, under the High Power Electric Propulsion (HiPEP) program. The development of a 100-kW-class ion propulsion system and power conversion systems are critical components to enable future nuclear-electric propulsion systems. In fiscal year 2003, a team composed of Glenn, the Boeing Company, General Dynamics, the Applied Physics Laboratory, the Naval Research Laboratory, the University of Wisconsin, the University of Michigan, and Colorado State University will perform a 6-month study that will result in the design of a 25-kW ion thruster, a propellant feed system, and a power processing architecture. The following 2 years will involve hardware development, wear tests, single-string tests of the thruster-power circuits and the xenon feed system, and subsystem service life analyses. The 2-kW-class ion propulsion technology developed for the Deep Space 1 mission will be used for NASA's discovery mission Dawn, which involves maneuvering a spacecraft to survey the asteroids Ceres and Vesta. The 6-kW-class ion thruster subsystem technology under NEXT is scheduled to be flight ready by calendar year 2006. The less mature 25- kW ion thruster system under HiPEP is expected to be ready for a flight advanced development program in calendar year 2006.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2002; NASA/TM-2003-211990
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  • 88
    Publication Date: 2018-06-02
    Description: System Power Analysis for Capability Evaluation (SPACE) is a computer model of the International Space Station's (ISS) Electric Power System (EPS) developed at the NASA Glenn Research Center. This uniquely integrated, detailed model can predict EPS capability, assess EPS performance during a given mission with a specified load demand, conduct what-if studies, and support on-orbit anomaly resolution.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2001; NASA/TM-2002-211333
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  • 89
    Publication Date: 2018-06-02
    Description: As part of the NASA Aviation Safety Program, a unique model-based diagnostics method that employs neural networks and genetic algorithms for aircraft engine performance diagnostics has been developed and demonstrated at the NASA Glenn Research Center against a nonlinear gas turbine engine model. Neural networks are applied to estimate the internal health condition of the engine, and genetic algorithms are used for sensor fault detection, isolation, and quantification. This hybrid architecture combines the excellent nonlinear estimation capabilities of neural networks with the capability to rank the likelihood of various faults given a specific sensor suite signature. The method requires a significantly smaller data training set than a neural network approach alone does, and it performs the combined engine health monitoring objectives of performance diagnostics and sensor fault detection and isolation in the presence of nominal and degraded engine health conditions.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2001; NASA/TM-2002-211333
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  • 90
    Publication Date: 2018-06-02
    Description: The Combustion Technologies Group at Lawrence Berkeley National Laboratory has developed simple, low-cost, yet robust combustion technologies that may change the fundamental design concept of burners for boilers and furnaces, and injectors for gas turbine combustors. The new technologies utilize lean premixed combustion and could bring about significant pollution reductions from commercial and industrial combustion processes and may also improve efficiency. The technologies are spinoffs of two fundamental research projects: An inner-ring burner insert for lean flame stabilization developed for NASA- sponsored reduced-gravity combustion experiments. A low-swirl burner developed for Department of Energy Basic Energy Sciences research on turbulent combustion.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2000; NASA/TM-2001-210605
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  • 91
    Publication Date: 2018-06-02
    Description: In an era of shrinking development budgets and resources, where there is also an emphasis on reducing the product development cycle, the role of system assessment, performed in the early stages of an engine development program, becomes very critical to the successful development of new aeropropulsion systems. A reliable system assessment not only helps to identify the best propulsion system concept among several candidates, it can also identify which technologies are worth pursuing. This is particularly important for advanced aeropropulsion technology development programs, which require an enormous amount of resources. In the current practice of deterministic, or point-design, approaches, the uncertainties of design variables are either unaccounted for or accounted for by safety factors. This could often result in an assessment with unknown and unquantifiable reliability. Consequently, it would fail to provide additional insight into the risks associated with the new technologies, which are often needed by decisionmakers to determine the feasibility and return-on-investment of a new aircraft engine.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2000; NASA/TM-2001-210605
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  • 92
    Publication Date: 2018-06-02
    Description: Unsteady ejectors are currently under investigation for use in some pulse-detonation-engine-based propulsion systems. Experimental measurements made in the past, and recently at the NASA Glenn Research Center, have demonstrated that thrust augmentation can be enhanced considerably when the driver is unsteady. In ejector systems, thrust augmentation is defined as = T(sup Total)/T(sup j), where T(sup Total) is the total thrust of the combined ejector and driving jet and T(sup j) is the thrust due to the driving jet alone. There are three images in this figure, one for each of the named thrust sources. The images are color contours of measured instantaneous vorticity. Each image is an ensemble average of at least 150 phase-locked measurements. The flow is from right to left, and the shape and location of each driver is shown on the far right of each image. The emitted vortex is a clearly defined "doughnut" of highly vortical (spinning) flow. In these planar images, the vortex appears as two distorted circles, one above, and one below the axis of symmetry. Because they are spinning in the opposite direction, the two circles have vorticity of opposite sign and thus are different colors. There is also a rectangle shown in each image. Its width represents the ejector diameter that was found experimentally to yield the highest thrust augmentation. It is apparent that the optimal ejector diameter is that which just "captures" the vortex: that is, the diameter bounding the outermost edge of the vortex structure. The exact mechanism behind the enhanced performance is unclear; however, it is believed to be related to the powerful vortex emitted with each pulse of the unsteady driver. As such, particle imaging velocimetry (PIV) measurements were obtained for three unsteady drivers: a pulsejet, a resonance tube, and a speaker-driven jet. All the drivers were tested with ejectors, and all exhibited performance enhancement over similarly sized steady drivers. The characteristic starting vortices of each driver are shown in these images. The images are color contours of measured instantaneous vorticity. Each image is an ensemble average of at least 150 phase-locked measurements. The flow is from right to left. The shape and location of each driver is shown on the far right of each image. The rectangle shown in each image represents the ejector diameter that was found experimentally to yield the highest thrust augmentation. It is apparent that the optimal ejector diameter is that which just "captures" the vortex: that is, the diameter bounding the outermost edge of the vortex structure. Although not shown, it was observed that the emitted vortex spread as it traveled downstream. The spreading rate for the pulsejet is shown as the dashed lines in the top image. A tapered ejector was fabricated that matched this shape. When tested, the ejector demonstrated superior performance to all those previously tested at Glenn (which were essentially of straight, cylindrical form), achieving a remarkable thrust augmentation of 2. The measured thrust augmentation is shown as a function of ejector length. Also shown are the thrust augmentation values achieved with the straight, cylindrical ejectors of varying diameters. Here, thrust augmentation is plotted as a function of ejector length for several families of ejector diameters. It can be seen that large thrust augmentation values are indeed obtained and that they are sensitive to both ejector length and diameter, particularly the latter. Five curves are shown. Four correspond to straight ejector diameters of 2.2, 3.0, 4.0, and 6.0 in. The fifth curve corresponds to the tapered ejector contoured to bound the emitted vortex. For each curve, there are several data points corresponding to different lengths. The largest value of thrust augmentation is 2.0 for the tapered ejector and 1.81 for the straight ejectors. Regardless of their diameters, all the ejectors trend toward peak performance at a particular leng. That the cross-sectional dimensions of optimal ejectors scaled precisely with the vortex dimensions on three separate pulsed thrust sources demonstrates that the action of the vortex is responsible for the enhanced ejector performance. The result also suggests that, in the absence of a complete understanding of the entrainment and augmentation mechanisms, methods of characterizing starting vortices may be useful for correlating and predicting unsteady ejector performance.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2003; NASA/TM-2004-212729
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  • 93
    Publication Date: 2017-10-04
    Description: The cost of implementing new technology in aerospace propulsion systems is becoming prohibitively expensive and time consuming. One of the main contributors to the high cost and lengthy time is the need to perform many large-scale hardware tests and the inability to integrate all appropriate subsystems early in the design process. The NASA Glenn Research Center is developing the technologies required to enable simulations of full aerospace propulsion systems in sufficient detail to resolve critical design issues early in the design process before hardware is built. This concept, called the Numerical Propulsion System Simulation (NPSS), is focused on the integration of multiple disciplines such as aerodynamics, structures and heat transfer with computing and communication technologies to capture complex physical processes in a timely and cost-effective manner. The vision for NPSS, as illustrated, is to be a "numerical test cell" that enables full engine simulation overnight on cost-effective computing platforms. There are several key elements within NPSS that are required to achieve this capability: 1) clear data interfaces through the development and/or use of data exchange standards, 2) modular and flexible program construction through the use of object-oriented programming, 3) integrated multiple fidelity analysis (zooming) techniques that capture the appropriate physics at the appropriate fidelity for the engine systems, 4) multidisciplinary coupling techniques and finally 5) high performance parallel and distributed computing. The current state of development in these five area focuses on air breathing gas turbine engines and is reported in this paper. However, many of the technologies are generic and can be readily applied to rocket based systems and combined cycles currently being considered for low-cost access-to-space applications. Recent accomplishments include: (1) the development of an industry-standard engine cycle analysis program and plug 'n play architecture, called NPSS Version 1, (2) A full engine simulation that combines a 3D low-pressure subsystem with a 0D high pressure core simulation. This demonstrates the ability to integrate analyses at different levels of detail and to aerodynamically couple components, the fan/booster and low-pressure turbine, through a 3D computational fluid dynamics simulation. (3) Simulation of all of the turbomachinery in a modern turbofan engine on parallel computing platform for rapid and cost-effective execution. This capability can also be used to generate full compressor map, requiring both design and off-design simulation. (4) Three levels of coupling characterize the multidisciplinary analysis under NPSS: loosely coupled, process coupled and tightly coupled. The loosely coupled and process coupled approaches require a common geometry definition to link CAD to analysis tools. The tightly coupled approach is currently validating the use of arbitrary Lagrangian/Eulerian formulation for rotating turbomachinery. The validation includes both centrifugal and axial compression systems. The results of the validation will be reported in the paper. (5) The demonstration of significant computing cost/performance reduction for turbine engine applications using PC clusters. The NPSS Project is supported under the NASA High Performance Computing and Communications Program.
    Keywords: Aircraft Propulsion and Power
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  • 94
    Publication Date: 2017-10-04
    Description: Aircraft engines are assemblies of dynamically interacting components. Engine updates to keep present aircraft flying safely and engines for new aircraft are progressively required to operate in more demanding technological and environmental requirements. Designs to effectively meet those requirements are necessarily collections of multi-scale, multi-level, multi-disciplinary analysis and optimization methods and probabilistic methods are necessary to quantify respective uncertainties. These types of methods are the only ones that can formally evaluate advanced composite designs which satisfy those progressively demanding requirements while assuring minimum cost, maximum reliability and maximum durability. Recent research activities at NASA Glenn Research Center have focused on developing multi-scale, multi-level, multidisciplinary analysis and optimization methods. Multi-scale refers to formal methods which describe complex material behavior metal or composite; multi-level refers to integration of participating disciplines to describe a structural response at the scale of interest; multidisciplinary refers to open-ended for various existing and yet to be developed discipline constructs required to formally predict/describe a structural response in engine operating environments. For example, these include but are not limited to: multi-factor models for material behavior, multi-scale composite mechanics, general purpose structural analysis, progressive structural fracture for evaluating durability and integrity, noise and acoustic fatigue, emission requirements, hot fluid mechanics, heat-transfer and probabilistic simulations. Many of these, as well as others, are encompassed in an integrated computer code identified as Engine Structures Technology Benefits Estimator (EST/BEST) or Multi-faceted/Engine Structures Optimization (MP/ESTOP). The discipline modules integrated in MP/ESTOP include: engine cycle (thermodynamics), engine weights, internal fluid mechanics, cost, mission and coupled structural/thermal, various composite property simulators and probabilistic methods to evaluate uncertainty effects (scatter ranges) in all the design parameters. The objective of the proposed paper is to briefly describe a multi-faceted design analysis and optimization capability for coupled multi-discipline engine structures optimization. Results are presented for engine and aircraft type metrics to illustrate the versatility of that capability. Results are also presented for reliability, noise and fatigue to illustrate its inclusiveness. For example, replacing metal rotors with composites reduces the engine weight by 20 percent, 15 percent noise reduction, and an order of magnitude improvement in reliability. Composite designs exist to increase fatigue life by at least two orders of magnitude compared to state-of-the-art metals.
    Keywords: Aircraft Propulsion and Power
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  • 95
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2018-06-06
    Description: Twenty-first-century aeropropulsion and power research will enable new transport engine and aircraft systems including: 1) Emerging ultralow noise and emissions with the use of intelligent turbofans; 2) Future distributed vectored propulsion with 24-hour operations and greater community mobility; 3) Research in hybrid combustion and electric propulsion systems leading to silent aircraft with near-zero emissions; and 4) The culmination of these revolutions will deliver an all-electric- powered propulsion system with zero-impact emissions and noise and high-capacity, on-demand operation
    Keywords: Aircraft Propulsion and Power
    Type: 2002 Computing and Interdisciplinary Systems Office Review and Planning Meeting; 1-13; NASA/TM-2003-211896
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  • 96
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2018-06-06
    Description: The objective is to develop the capability to numerically model the performance of gas turbine engines used for aircraft propulsion. This capability will provide turbine engine designers with a means of accurately predicting the performance of new engines in a system environment prior to building and testing. The 'numerical test cell' developed under this project will reduce the number of component and engine tests required during development. As a result, the project will help to reduce the design cycle time and cost of gas turbine engines. This capability will be distributed to U.S. turbine engine manufacturers and air framers. This project focuses on goals of maintaining U.S. superiority in commercial gas turbine engine development for the aeronautics industry.
    Keywords: Aircraft Propulsion and Power
    Type: 2002 Computing and Interdisciplinary Systems Office Review and Planning Meeting; 73-78; NASA/TM-2003-211896
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  • 97
    Publication Date: 2018-06-02
    Description: NASA's previous Advanced Subsonic Technology (AST) Noise Reduction Program delivered the initial technologies for meeting a 10-year goal of a 10-dB reduction in total aircraft system noise. Technology Readiness Levels achieved for the engine-noise-reduction technologies ranged from 4 (rig scale) to 6 (engine demonstration). The current Quiet Aircraft Technology (QAT) project is building on those AST accomplishments to achieve the additional noise reduction needed to meet the Aerospace Technology Enterprise's 10-year goal, again validated through a combination of laboratory rig and engine demonstration tests. In order to meet the Aerospace Technology Enterprise goal for future aircraft of a 50- reduction in the perceived noise level, reductions of 4 dB are needed in both fan and jet noise. The primary objectives of the Engine Noise Reduction Systems (ENRS) subproject are, therefore, to develop technologies to reduce both fan and jet noise by 4 dB, to demonstrate these technologies in engine tests, and to develop and experimentally validate Computational Aero Acoustics (CAA) computer codes that will improve our ability to predict engine noise.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2003; NASA/TM-2004-212729
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  • 98
    Publication Date: 2018-06-02
    Description: The Ultra-Efficient Engine Technology (UEET) Project is formulated according to the Office of Aerospace Technology's objectives as outlined in the NASA Strategic Plan. It is directly related to the "protect the environment" objective and will make progress toward the "increase mobility" and "support national security" objectives as well. UEET technologies will impact future civil and military aircraft and will benefit the development of future space transportation propulsion systems. UEET Project success will, therefore, depend on developing revolutionary, but affordable, technology solutions that are inherently safe and reliable and thus can be incorporated in future propulsion system designs. In fiscal year 2003, UEET became part of NASA's Vehicle Systems Program and continues to evolve its programmatic role. The Vehicle Systems Program aims to develop breakthrough technologies and methodologies, push the boundaries of flight through research on advanced vehicle concepts, respond quickly to industry and the Department of Defense on critical safety and other issues, and provide facilities and expert consultation for industry and other Government agencies during product development.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2003; NASA/TM-2004-212729
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  • 99
    Publication Date: 2019-06-28
    Description: A comparison of the operating characteristics of 75-millimeter-bore (size 215) cylindrical-roller one-piece inner-race-riding cage-type bearings was made using a laboratory test rig and a turbojet engine. Cooling correlation parameters were determined by means of dimensional analysis, and the generalized results for both the inner- and outer-race bearing operating temperatures are compared for the laboratory test rig and the turbojet engine. Inner- and outer-race cooling-correlation curves were obtained for the turbojet-engine turbine-roller bearing with the same inner- and outer-race correlation parameters and exponents as those determined for the laboratory test-rig bearing. The inner- and outer-race turbine roller-bearing temperatures may be predicted from a single curve, regardless of variations in speed, load, oil flow, oil inlet temperature, oil inlet viscosity, oil-jet diameter or any combination of these parameters. The turbojet-engine turbine-roller-bearing inner-race temperatures were 30 to 60 F greater than the outer-race-maximum temperatures, the exact values depending on the operating condition and oil viscosity; these results are in contrast to the laboratory test-rig results where the inner-race temperatures were less than the outer-race-maximum temperatures. The turbojet-engine turbine-roller bearing, maximum outer-race circumferential temperature variation was approximately 30 F for each of the oils used. The effect of oil viscosity on inner- and outer-race turbojet-engine turbine-roller-bearing temperatures was found to be significant. With the lower viscosity oil (6x10(exp -7) reyns (4.9 centistokes) at 100 F; viscosity index, 83), the inner-race temperature was approximately 30 to 35 F less than with the higher viscosity oil (53x10(exp -7) reyns (42.8 centistokes) at 100 F; viscosity index, 150); whereas the outer-race-maximum temperatures were 12 to 28 F lower with the lower viscosity oil over the DN range investigated.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-E51I05
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  • 100
    Publication Date: 2019-06-28
    Description: A literature survey was conducted to determine the relation between aircraft ignition sources and inflammables. Available literature applicable to the problem of aircraft fire hazards is analyzed and, discussed herein. Data pertaining to the effect of many variables on ignition temperatures, minimum ignition pressures, and minimum spark-ignition energies of inflammables, quenching distances of electrode configurations, and size of openings incapable of flame propagation are presented and discussed. The ignition temperatures and the limits of inflammability of gasoline in air in different test environments, and the minimum ignition pressure and the minimum size of openings for flame propagation of gasoline - air mixtures are included. Inerting of gasoline - air mixtures is discussed.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-TN-2227
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