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  • Other Sources  (830)
  • Aerodynamics  (800)
  • Deutschland
  • LUNAR AND PLANETARY EXPLORATION
  • Magnetism
  • 2010-2014  (574)
  • 1960-1964  (154)
  • 1950-1954  (84)
  • 1925-1929
Collection
Language
Years
Year
  • 1
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    In:  AFJZ 125, Seite 153-159
    Publication Date: 1954
    Description: Darstellung eines Klimaindexes mit direktem Bezug zu Holzzuwachs in Wäldern KATASTER-BESCHREIBUNG: Formel für Klimaindex der mit dem durchschnittlichen Gesamtzuwachs korreliert ist KATASTER-DETAIL: Delta T++: Tmj=2K (alle anderen Faktoren=konstant), dann Zuwachs sinkt um 7.5%; Delta Nied--: prozentualer Rückgang im Jahresniederschlag (alle anderen Faktoren=konstant), dann gleicher prozentualer Rückgang im Zuwachs; I=(P x pn x (Z - 60))/(Tmj - 10) x 92 x 100 (Tmj - mittlere Temperatur Mai – Juli P – jährliche Niederschlagssumme [mm] pn – Anzahl der Tage mit Niederschlag〉=0.1mm May - July Z - Anzahl der Tage ohne Frost (〉 0°))
    Keywords: Deutschland
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  • 2
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    In:  Gesunde Pflanzen 5; p.53-57
    Publication Date: 1953
    Description: Der Autor fasst einige Kenntnisse über die San Jose Schildlaus zusammen und versucht ihre rasche Verbreitung in Deutschland zu erklären. Als wichtiger klimatischer Einflußfaktor v.a. in höheren Lagen werden die Wintertemperaturen bzw. wechselndes Wetter und Spätfröste im Spätwinter genannt. KATASTER-BESCHREIBUNG: KATASTER-DETAIL:
    Keywords: Deutschland ; 1949-1952
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  • 3
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    In:  Deutsche Landwirtschaftliche Presse, Jahrgang 52, Nr. 38, p. 450
    Publication Date: 1925
    Description: Allgemeine Beobachtungen zum Rostbefall von Weizen im Jahr 1925 trotz langer Trockenperioden KATASTER-BESCHREIBUNG: Einfluss des Niederschlags auf die Infektion; auch kurze starke Niederschläge zwischen langen Trockenperioden sind ausreichend um einen großflächigen Befall zu bewirken. KATASTER-DETAIL: Delta Nied +, dann Infektion +;
    Keywords: Deutschland ; 1925 ; Anbautermine ; Niederschlag ; Pflanzenkrankheit ; Trockenheit ; Weizen
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  • 4
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    In:  Berichte des Deutschen Wetterdienstes, Nr. 92, Band 13,
    Publication Date: 1964
    Description: Beurteilung des großräumigen Witterungsablaufs und Überprüfung der alten Temperaturwerte KATASTER-BESCHREIBUNG: - KATASTER-DETAIL: -
    Keywords: Deutschland ; 1708-1709 ; Temperatur ; Witterung
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  • 5
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    In:  ???
    Publication Date: 2013
    Description: Simulationen mithilfe des Models 4C zu möglichen Auswirkungen der Klimaänderungen des RCP 8.5 Klimaszenariums auf Wälder in Deutschland Kiefer Fichte Eiche Buche KATASTER-BESCHREIBUNG: Auswirkungen des Klimawandels (Temperatur, Niederschlag, CO2-Gehalt der Atmosphäre) auf die Wälder KATASTER-DETAIL: Delta T (Frühjahr) + und Delta Nied (Frühjahr) -, dann Produktivität der Wälder -; Delta C02 + um 25 - 30 %, dann Produktion der Wälder + um 9 - 20%; Delta T + (an nicht wasserlimitierten Standorten), dann Produktivität der Wälder +; Delta CO2+, dann Wassernutzungseffizienz der Wälder +; Delta T (Sommer) +, dann Waldbrandgefahr +; Delta T (Sommer) + und Delta Nied (Sommer) - (= WaBi -), dann Trockenstress der Wälder + um bis zu 9% und dann Produktivität der Wälder -; Delta T (Sommer) + und Delta Nied (Sommer) -, dann Populationsdichte Kiefern-Großschädlinge +;
    Keywords: Deutschland ; 20. und 21. Jahrhundert ; Boden ; Buche ; Eiche ; Fichte ; Forst ; Kiefer ; Klima ; Niederschlag ; Pflanzenschädling ; Phänologie ; Sturmschaden ; Temperatur ; Trockenheit ; Verdunstung ; Waldbrand ; Waldwachstum ; Wassermangel ; Wind ; Grundwasser ; Modell
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  • 6
    Publication Date: 2012
    Description: Übersicht über bisherige, dokumentiere Zusammenhänge einer Klimaänderung und pilzliche Krankheiten in Raps, Abschätzungen über das Auftreten von Verticillium longisporum, Sclerotinia sclerotiorum, Alternaria brassicae und Phoma lingam an Raps in der Zukunft KATASTER-BESCHREIBUNG: Projektionen über das Auftreten von pilzlichen Pathogenen in Raps, Basiszeitraum 1971-2000, Szenario A1B, REMO, 2001-2030 und 2071-2100, Zusammenhang zwischen Grad-Tagen(〉0°C), Pflanzenentwicklung und Krankheitsparametern als Regressionsfunktionen im Artikel, jedoch sind feiner aufgelöste Projektion von RCM als Tageswerte erforderlich, um Wachstumszyklen zu simulieren und genauere Aussagen zu erhalten KATASTER-DETAIL: Delta T +, dann Zunahme von Verticillium longisporum, Sclerotinia sclerotiorum, Alternaria brassicae und Phoma lingam an Raps, Signal verstärkt im Szenarienzeitraum 2071-2100, Abnahme von Pyrenopeziza brassicae
    Keywords: Deutschland ; Sachsen, Niedersachsen, Norddeutschland ; 1971-2000 ; Szenarien ; Infektionskrankheiten ; Temperatur ; Raps
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  • 7
    Publication Date: 1927
    Keywords: Deutschland ; Umweltmedizin ; Infektionskrankheiten
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  • 8
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    In:  Ber. Deut. Bot. Gesellschaft 45:638-643.
    Publication Date: 1927
    Description: Einfluss der Temperatur auf die Flora und ihre Verteilung in Deutschland KATASTER-BESCHREIBUNG: KATASTER-DETAIL:
    Keywords: Deutschland ; Botanik ; Klima ; Phänologie ; Temperatur
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  • 9
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    In:  Landwirtschaftl. Jahrbuch (64)817-930.
    Publication Date: 1926
    Description: Zusammenhang Klima, Witterung und Ertrag von Gräsern und Klee KATASTER-BESCHREIBUNG: KATASTER-DETAIL:
    Keywords: Deutschland ; Boden ; Ertrag ; Klima ; Landwirtschaft
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  • 10
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    In:  Met. Zeitschr. 43:352-355.
    Publication Date: 1926
    Description: Einfluss von Temperatur und Niederschlag auf die Vegetation KATASTER-BESCHREIBUNG: KATASTER-DETAIL:
    Keywords: Deutschland ; 1900-1925 ; Klima ; Niederschlag ; Temperatur
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  • 11
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    In:  Deut. Landwirtschaflt. Presse 55:94-95.
    Publication Date: 1928
    Description: Übersicht über die Literatur zum Einfluss des Wetters auf die Kulturpflanzen KATASTER-BESCHREIBUNG: Milder und trockener Winter wirkt positiv auf die Weizenerträge, kalter und niederschlagsreicher Winter eher negativ, Betrachung für Norddeutschland KATASTER-DETAIL:
    Keywords: Deutschland ; 1900-1926 ; Kartoffeln ; Ertrag ; Getreide ; Hafer ; Landwirtschaft ; Niederschlag ; Roggen ; Temperatur ; Trockenheit ; Witterung ; Gerste
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  • 12
    Publication Date: 1929
    Description: Einfluss der Witterungsfaktoren auf verschiedene Kulturen und die Betriebssysteme KATASTER-BESCHREIBUNG: KATASTER-DETAIL:
    Keywords: Deutschland ; Witterung
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  • 13
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    In:  Arbeiten aus der biologischen Bunbdesanstalt für Land- und Forstwirtschaft 14, Heft 1; Parey, Springer, Berlin; p.1-76
    Publication Date: 1925
    Description: Detaillierte Auflistung des Maikäferauftretens verschiedener Jahre aus dem Zeitraum 1900-1920 aus ganz Deutschland in Bezirks- teilw. sogar Gemeindeauflösung wird gegeben. Der Einfluß der Temperatur in Form von 9°C Mitteltemperatur als Grenze für die Generationenanzahl der beiden Maikäferarten Melolontha melolontha L. und Melolontha hippocastani F. wird diskutiert. Eine Karte über die Generationsdauer der beiden Maikäferarten im deutschen Reich, teilweise auf Bezirksebene, ist enthalten. KATASTER-BESCHREIBUNG: KATASTER-DETAIL:
    Keywords: Deutschland ; 1855-1923 ; Forst ; Pflanzenschädling
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  • 14
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    In:  P. Paray (Berlin), 317 Seiten
    Publication Date: 1928
    Description: Beziehung der Witterungseinflüsse auf die Knollenerträge, Auswertungen von Kartoffelkulturstationsergebnissen KATASTER-BESCHREIBUNG: KATASTER-DETAIL:
    Keywords: Deutschland ; 1900-1925
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  • 15
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    In:  Landw. Forsch. Darmstadt, 2. Sonderheft: 51-60
    Publication Date: 1952
    Description: Überblick über die Zusammenhänge zwischen Klima bzw. Witterung und Pflanzenqualität von Ackerfrüchten, Wiesengräsern, Obst, Gemüse, Gewürzpflanzen und Wein KATASTER-BESCHREIBUNG: Einfluss der Witterung (Temperatur, Niederschlag, Sonnenschein, Strahlung) auf die Qualität verschiedener Anbaukulturen KATASTER-DETAIL: Delta T (Erntezeit) + und Delta Nied (Erntezeit) -, dann Feuchtigkeitsgehalt der Körner (Ackerfrüchte) -; Delta T (Erntezeit) - und Delta Nied (Erntezeit) +, dann Feuchtigkeitsgehalt der Körner (Ackerfrüchte) +; Delta T (Zeit der Kornausbildung) ++ und Delta Nied (Zeit der Kornausbildung) -, dann Stärkegehalt der Körner (Ackerfrüchte) - und Einweißgehalt der Körner + sowie Größe der Körner -; Delta T (Zeit von Milch- zur Voll- und Todreife) + und Delta Sonn (Zeit von Milch- zur Voll- und Todreife) + und Delta Nied (Zeit von Milch- zur Voll- und Todreife) -, dann besserer Kleber und gute Backfähigkeit; Delta blaue Strahlung +, dann Einweißgehalt - und Kleberqualität +; Delta Nied (Juni, Juli) +, dann Fermenttätigkeit +; Informationen zu den anderen Anbaukulturen: siehe Artikel
    Keywords: Deutschland ; 1. Hälfte 20. Jahrhundert ; Ertrag ; Getreide ; Niederschlag ; Temperatur ; Trockenheit ; Wachstum ; Witterung ; Hackfrüchte ; Obst ; Sonnenscheindauer ; Wein ; Gemüse
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  • 16
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    In:  Zeitschrift für Acker- und Pflanzenbau 98, Heft 1; p.119-125
    Publication Date: 1954
    Description: Berichte über Warndienste und Prognoseverfahren der kritischen Witterungsperiodes für Phytophthora infestans aus verschiedenen Ländern (Niederlande, England, Irland, Deutschland) werden zusammengefasst. Es wird beispielhaft auf eine andere Arbeit verwiesen, die die Befallsbedingungen für Krautfäule in Schleswig-Holstein beschreibt. Eine Regel aus klimatischen Parametern für die kritische Periode in Schleswig-Holstein wird rezitiert. Zudem wird eine Regel für das Nulldatum (Gefährdungsbeginn) aus der Literatur für Deutschland. KATASTER-BESCHREIBUNG: Regel für die kritische Periode bei Phytophthora infestans für Schleswig-Holstein. Regel für den Zeitpunkt des Nulldatums in Deutschland für 4 Sorten. KATASTER-DETAIL: Nulldatum liegt bei 800°C bzw. 1100°C Temperatursumme der Tagesmitteltemperaturen ab 1.April (für die Sorten Erstling & Sieglinde bzw. Bona & Flava). Kritische Periode -〉 2 Tage in Folge tmax 〉 23°C, tmin 〉= 10°C, Dampfdruck im Tagesmittel 〉 12mm, mittlere Bewölkung 〉= 5/10; diese Bedingungen treten nur auf, wenn der Warmsektor eines Tiefdruckgebietes über Schleswig-Holstein liegt und in diesem Warmsektor subtropische Luftmassen beobachtet werden.
    Keywords: Deutschland ; 1949-1953 ; Kartoffeln ; Pflanzenkrankheit ; Hackfrüchte
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  • 17
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    In:  Internes Arbeitsmaterial des PIK, .... fs01/guests\Martin.Wodinski\PIK-COLLECTION\SLIDES-POOL\RD2\
    Publication Date: 2010
    Description: Kalkulation der Hitzetage (Tmax 〉 30°C) anhand es PIK/DWD Datensatzes für 1951-2006 im Jahr, und für den Zeitraum 2051-60, Szenario A1B, als Mittel und Differenzkarten KATASTER-BESCHREIBUNG: Hitzetage (Tmax 〉 30°C) in Deutschland KATASTER-DETAIL: Zunahme der Hitzetage (Tmax 〉 30°C) 2051-2060 vs. 1951-2006 um bis zu 16 Tagen im Jahr, stärkste Zunahme Rheingragben, Rheinland-Pfalz, Niederrhein, Kölner Bucht und Mitteldeutschland
    Keywords: Deutschland ; 1951-2006, 2051-60 ; Temperatur ; Witterungsextreme
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  • 18
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    In:  Hattermann, F. F., Z. W. Kundzewicz, H. S., T. Vetter, W. Kron, O. Burghoff, Y. Hauf, V. Krysanova, F.-W. Gerstengarbe, P. Werner, B. Merz, A. Bronstert (2012a), Flood risk in holistic perspective - observed changes in Germany. In: Changes of flood risk in Europe, IAHS Press, Wallingford, 212-237.
    Publication Date: 2012
    Description: Simulierte und beobachtete Trends der jährlichen Hochwassermaxima KATASTER-BESCHREIBUNG: Trend der Zu- bzw. Abnahme der Andauer der jährlichen Hochwassermaxima in Deutschland für die Vergangenheit KATASTER-DETAIL: Abnahme des mittleren jährlichen Abflusses um 35 % in Baden-Württemberg (Pegel Achstetten/Baierzer Rot) bzw. 21 % in Brandenburg (Pegel Ketzin/Havel) Zunahme des mittleren jährlichen Abflusses um 84 % in Bayern (Pegel Breitenbachkamm/Breitach) bzw. 74 % in Bayern (Pegel Kalteneck/Ilz)
    Keywords: Deutschland ; 1951-2003 ; Witterungsextreme ; Hochwasser
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  • 19
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    In:  Der Obstanbau, p. 184-185
    Publication Date: 1953
    Description: Beobachtungen zur Masseneinablage und zur Witterung KATASTER-BESCHREIBUNG: Zusammenhang zischen der Luftfeuchtigkeit und dem Flug sowie der Eiablage des Apfelwicklers KATASTER-DETAIL: Delta Relf (Trockenperioden) +, dann Flug + und Eiablage +
    Keywords: Deutschland ; 1952 ; Pflanzenschädling ; Trockenheit
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  • 20
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    In:  Neue Mitt. Landwirtsch., p. 395-396
    Publication Date: 1951
    Description: Verbale Beschreibung des bisherigen Wissens über die Blattfleckenkrankheit und deren Erreger KATASTER-BESCHREIBUNG: Zusammenhang zwischen Witterung (Temperatur, Luftfeuchte) und dem Auftreten der Krankheit KATASTER-DETAIL: Delta T (Sommer) + und Delta Nied (Sommer) +, dann Auftreten von Cercospora +; Delta Relf +, dann Anzahl und Größe der Konidien +; Relf 〉 98%, dann Keimung der Konidien; Delta T: 20°C 〈 T 〈 30°C, dann schnellste Keimung der Konidien; 25°C 〈 T 〈 30°C, dann optimales Wachstum des Myzels; °C 〉 T 〈 40°C, dann kein Wachstum des Myzels
    Keywords: Deutschland ; 1950 ; Zuckerrüben ; Pflanzenkrankheit ; Temperatur ; Witterung
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  • 21
    Publication Date: 1950
    Description: Einfuß der Temperatur, Sonnenscheindauer und des Niederschages auf die Reifedauer des Roggens KATASTER-BESCHREIBUNG: KATASTER-DETAIL:
    Keywords: Deutschland ; 1936-37 ; Ertrag ; Phänologie ; Roggen ; Trockenheit ; Wachstum ; Witterung
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  • 22
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    In:  Internes Arbeitsmaterial des PIK, .... fs01/guests\Martin.Wodinski\PIK-COLLECTION\SLIDES-POOL\RD2\
    Publication Date: 2010
    Description: Kalkulation der Klimatischen Wasserbilanz (mm) anhand es PIK/DWD Datensatzes für 1951-2006 im Jahr, und für den Zeitraum 2051-60, Szenario A1B, als Mittel und Differenzkarten KATASTER-BESCHREIBUNG: Jährliche Klimatischen Wasserbilanz WABI (Niederschlag - pot. Verdunstung nach Turc-Ivanov) für Deutschland KATASTER-DETAIL: Zu- bzw. Abnahme der (WABI) 2051-2060 vs. 1951-2006 von 200 - (-100) im Westen der BRD, in Ostdeutschland stärkere, einheitliche Abnahme der WABI um bis zu 300mmm
    Keywords: Deutschland ; 1951-2006, 2051-60 ; Niederschlag ; Temperatur ; Witterungsextreme
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  • 23
    Publication Date: 1954
    Description: Zunächst werden Kardinalwerte der verschiedenen Entwicklungsphasen von Phytophthora infestans aus der Literatur zusammengefasst. Im folgenden erfolgt ein Review über den Einfluß von Temperatur und Feuchte auf die Überwinterung, sowie den Einfluß des Windes auf die Verbreitung. KATASTER-BESCHREIBUNG: KATASTER-DETAIL:
    Keywords: Deutschland ; 1949-1953 ; Kartoffeln ; Pflanzenkrankheit ; Hackfrüchte
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  • 24
    Publication Date: 1929
    Description: Lage der Hochs nördlich und südlich des 50. Breitengrades und ihre Bedeutung für die Witterung und Ernteerträge in Mitteldeutschland KATASTER-BESCHREIBUNG: KATASTER-DETAIL: Tmit+ (Janurar, Februar, März, Mai und Dezember) durch Abnahem der barometrischen Nordlagen Tmit- (August, September) durch Zunahme der barometrischen Nordlagen Nied+ (Janurar, Apri,, Mai, August, September, Dezember) durch Abnahmen der barometrischen Nordlagen (entspricht Zunahmen der Südlagen!) Nied- (Februar, März, Oktober und November) durch Abnahmen der barometrischen Nordlagen (entspricht Zunahmen der Südlagen!)
    Keywords: Deutschland ; 1900-1925 ; Luftfeuchte ; Ertrag ; Getreide ; Landwirtschaft ; Niederschlag ; Temperatur ; Trockenheit ; Witterung ; Sonnenscheindauer
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  • 25
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    In:  Georgine, Jahrgang 102, Nr. 68, p. 806-807
    Publication Date: 1925
    Description: Biologie und Bekämpfung von Fritfliege, Getreideblumenfliege, scheckige oder gelbe Halmfliege, Weizenfliege, Hessenfliege KATASTER-BESCHREIBUNG: Einfluss der Witterung (Temperatur, Niederschlag und Wind) auf die Schädlinge KATASTER-DETAIL: Delta T (Winter) +, Anzahl Maden der Halmfliege +; Delta Nied (September) + und Delta Wind (September) +, dann Hessenfliege -
    Keywords: Deutschland ; 1903-1925 ; Insekten ; Anbautermine ; Boden ; Ertrag ; Getreide ; Hafer ; Niederschlag ; Pflanzenschädling ; Temperatur ; Vegetationsperiode ; Weizen ; Wind ; Witterung ; Düngung ; Gerste
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  • 26
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    In:  Nassauer Land 108, p. 185
    Publication Date: 1926
    Description: Beobachtungen zum Gelbrostbefall von Weizen, Roggen und Gerste KATASTER-BESCHREIBUNG: - KATASTER-DETAIL: -
    Keywords: Deutschland ; 1926 ; Infektionskrankheiten ; Getreide ; Pflanzenkrankheit ; Roggen ; Weizen ; Gerste
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  • 27
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    In:  Other Sources
    Publication Date: 2015-04-02
    Description: Effect of rapid pressure decay on solid propellant combustion
    Keywords: Aerodynamics
    Type: ARS Journal; Volume 31; No. 11; 1584-1586
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  • 28
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    In:  Other Sources
    Publication Date: 2011-08-17
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: N. Am. Aviation Proc. of the 12th Lunar and Planetary Exploration Colloq., Vol. 3, No. 2; p 29-36
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  • 29
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    In:  Other Sources
    Publication Date: 2011-08-17
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: N. Am. Aviation Proc. of the 12th Lunar and Planetary Exploration Colloq., Vol. 3, No. 2; p 47-48
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  • 30
    Publication Date: 2017-03-07
    Description: The effect of mass addition on the flow over bodies moving at hypersonic speeds has been studied by several investigators (e.g., Cresci and Libby). In most of this work, primary attention logically has been directed toward the effects of foreign-gas injection on heat transfer and pressure distributions, and, principally for this reason, most of the work ha been done at zero angle of attack. The foreign gas can be provided either by some active injection system or by the action of an ablation heat shield. With increasing rates of injection, the basic flow about the body can be affected significantly. One such effect was observed in the paper by Cresci and Libby, where it was shown that the shockwave standoff distance can be increased by gas injection at the nose of a body.
    Keywords: Aerodynamics
    Type: AIAA Journal; Volume 1; No. 4; 939-940
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  • 31
    Publication Date: 2018-06-06
    Description: Motivation - Higher loading on Low-Pressure Turbine (LPT) airfoils: Reduce airfoil count, weight, cost. Increase efficiency, and Limited by suction side separation. Growing understanding of transition, separation, wake effects: Improved models. Take advantage of wakes. Higher lift airfoils in use. Further loading increases may require flow control: Passive: trips, dimples, etc. Active: plasma actuators, vortex generator jets (VGJs). Can increased loading offset higher losses on high lift airfoils. Objectives: Advance knowledge of boundary layer separation and transition under LPT conditions. Demonstrate, improve understanding of separation control with pulsed VGJs. Produce detailed experimental data base. Test and develop computational models.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 473-494; NASA/CP-2010-216112
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  • 32
    Publication Date: 2018-06-06
    Description: In assessing the results please recall that the Mach number regimes and model geometries differ considerably. Selection of the radius of curvature at the 10% chord location is consistent but arbitrary, although it does seem representative for most blades and gives a good fit for the results. Measured spanwise wavelengths of the periodic vortex arrays on blading are predicted well by the Kestin and Wood theory. If this behavior is at all common it could have implications for turbine aerodynamic and blade cooling design. The outcome is to establish that organized streamwise vorticity may occur more frequently on convex surfaces, such as turbine blade suction surfaces, than hitherto appreciated. Investigations and predictions of flow behavior should be extended to encompass that possibility.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 61-92; NASA/CP-2010-216112
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  • 33
    Publication Date: 2018-06-06
    Description: Active Flow Control increases the permissible aerodynamic loading. Curved surface near the trailing edge ("Coanda surface"): a) increases turning -〉 higher pressure ratio. b) controls boundary layer separation -〉 increased surge margin. Objective: Reduce the number of vanes or compressor stages. Constraints: 1. In a real compressor, the vane must still function entirely without blowing. 2. Maintain the flow exit angle of the reference stator despite the resulting increase in stator loading.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 417-434; NASA/CP-2010-216112
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  • 34
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    In:  CASI
    Publication Date: 2018-06-06
    Description: Effects of roughness in boundary layers have to be addressed. Until adverse pressure gradient effects are understood, roughness will not significantly drive design. Mechanisms responsible for separation not understood. Effects on Zero Pressure Gradient boundary layers (shear stress). Effects on separation in pressure gradient (prediction of separation). Effect on scalar transport (heat transfer) not understood. Model for skin friction needed in simulations - first grid point likely to be in buffer layer. Definition of roughness important for useful experiments. A lot of validation experiments will be needed. How to get to ks for roughness of engineering interest? - depends on wavelength height, etc. for engineering interest? Re-discovering the wheel should be avoided: existing knowledge (theoretical and experimental) should find its way into the engineering models. It is a task of the industry to filter out the existing information in the literature for results relevant to its application, being external or internal.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 589-600; NASA/CP-2010-216112
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  • 35
    Publication Date: 2018-06-05
    Description: The greatest efficiency for a lifting surface at supersonic speeds, according to the theoretical considerations of reference 1, can be attained if the leading edge is swept well behind the Mach cone and the highest aspect ratio which is structurally possible is employed. Such a wing, designed for a Mach number of 3.0, would have 80 deg. of sweepback. Aeroelastic effects have 〈 been shown 3 to be considerable for a wing with 60deg of sweepback and designed for a Mach number of 2.0. The wing shown was found theoretically to have considerable loss in maximum lift-drag ratio attributable to aeroelasticity. This wing has 12-per cent-thick Clark-Y airfoils normal to the wing leading edge. If it were of solid aluminum and flying at a dynamic pressure of 2,400 lbs./sq.ft. (flexibility parameter qb(exp. 4) /El(0) = 7.8), analysis indicates that the wing would deflect so as to reduce the maximum lift-drag ratio about 30 per cent.
    Keywords: Aerodynamics
    Type: Journal of the Aerospace Sciences; Volume 27; No. 8; 634-635
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  • 36
    Publication Date: 2018-06-28
    Description: Challenges to computational aerothermodynamic (CA) simulation and validation of hypersonic flow over planetary entry vehicles are discussed. Entry, descent, and landing (EDL) of high mass to Mars is a significant driver of new simulation requirements. These requirements include simulation of large deployable, flexible structures and interactions with reaction control system (RCS) and retro-thruster jets. Simulation of radiation and ablation coupled to the flow solver continues to be a high priority for planetary entry analyses, especially for return to Earth and outer planet missions. Three research areas addressing these challenges are emphasized. The first addresses the need to obtain accurate heating on unstructured tetrahedral grid systems to take advantage of flexibility in grid generation and grid adaptation. A multi-dimensional inviscid flux reconstruction algorithm is defined that is oriented with local flow topology as opposed to grid. The second addresses coupling of radiation and ablation to the hypersonic flow solver--flight- and ground-based data are used to provide limited validation of these multi-physics simulations. The third addresses the challenges of retro-propulsion simulation and the criticality of grid adaptation in this application. The evolution of CA to become a tool for innovation of EDL systems requires a successful resolution of these challenges.
    Keywords: Aerodynamics
    Type: Aerothermodynamic Design, Review on Ground Testing and CFD; 11-1 - 11-44; RTO-EN-AVT-186
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  • 37
    Publication Date: 2018-06-28
    Description: The Electric Arc Shock Tube (EAST) facility and the Hypervelocity Free Flight Aerodynamic Facility (HFFAF) at NASA Ames Research Center are described. These facilities have been in operation since the 1960s and have supported many NASA missions and technology development initiatives. The facilities have world-unique capabilities that enable experimental studies of real-gas aerothermal, gas dynamic, and kinetic phenomena of atmospheric entry.
    Keywords: Aerodynamics
    Type: Aerothermodynamic Design, Review on Ground Testing and CFD; 4-1 - 4-24; RTO-EN-AVT-186
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  • 38
    Publication Date: 2019-05-25
    Description: A simplified method is presented for estimating the lift-curve slope of irregular planform wings at subsonic speeds and low angles of attack. The present process is an extension of the method derived in NACA Technical Note 3911 and enables quick estimates of subsonic liftcurve slope, to be made whereas more refined procedures require considerable time and computation. Comparison of experimental and estimated values for a wide range of wing planforms having discontinuous spanwise sweep variation indicates good agreement. A comparison of the present procedure with a 20-step vortex method (NACA Research Memorandum L50L13) indicated good agreement for a variable-sweep configuration.
    Keywords: Aerodynamics
    Type: NASA-TM-X-525
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  • 39
    Publication Date: 2019-06-28
    Description: No abstract available
    Keywords: Aerodynamics
    Type: NACA-RM-SL54F28
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  • 40
    Publication Date: 2019-06-28
    Description: The transonic similarity rules have been applied to the correlation of experimental data for a series of 22 rectangular wings having symmetrical NACA 63A-series sections, aspect ratios from 1/2 to 6, and thicknesses from 2 to 10 percent. The data were obtained by use of the transonic bump technique over a Mach number range from 0.40 to 1.10, corresponding to a Reynolds number range from 1.25 to 2.05 million. The results show that it is possible to correlate experimental data throughout the subsonic, transonic, and moderate supersonic regimes by using the transonic similarity parameters in forms which are consistent with the Prandtl-Glauert rule of linearized theory. The multiple families of basic data curves for the various aspect ratios and thickness ratios have been summarized in single presentations involving only one geometric variable - the product of the aspect ratio and the l/3 power of the thickness ratio.
    Keywords: Aerodynamics
    Type: NACA-RM-A51L17b
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  • 41
    Publication Date: 2019-06-28
    Description: Experiments have been made at Stanford University to determine the performance characteristics of plane-wall, two-dimensional diffusers which were so proportioned as to insure reasonable approximation of two-dimensional flow. All of the diffusers had identical entrance cross sections and discharged directly into a large plenum chamber; the test program included wide variations of divergence angle and length. During all tests a dynamic pressure of 60 pounds per square foOt was maintained at the diffuser entrance and the boundary layer there was thin and fully turbulent. The most interesting flow characteristics observed were the occasional appearance of steady, unseparated, asymmetric flow - which was correlated with the boundary-layer coalescence - and the rapid deterioration of flow steadiness - which occurred as soon as the divergence angle for maximum static pressure recovery was exceeded. Pressure efficiency was found to be controlled almost exclusively by divergence angle, whereas static pressure recovery was markedly influenced by area ratio (or length) as well as divergence angle. Volumetric efficiency. diminished as area ratio increased, and at a greater rate with small lengths than with large ones. Large values of the static-pressure-recovery coefficient were attained only with long diffusers of large area ratio; under these conditions pressure efficiency was high and. volumetric efficiency low. Auxiliary tests with asymmetric diffusers demonstrated that longitudinal pressure gradient, rather than wall divergence angle, controlled flow separation. Others showed that the addition of even a short exit duct of uniform section augmented pressure recovery. Finally, it was found that the installation of a thin, central, longitudinal partition suppressed flow separation in short diffusers and thereby improved pressure recovery
    Keywords: Aerodynamics
    Type: NACA-TN-2888
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  • 42
    Publication Date: 2019-06-28
    Description: This report contains those results of the theory of wings and of wing sections which are of immediate practical value. They are proved and demonstrated by the use of the simple conceptions of "kinetic energy" and "momentum" only, familiar to every engineer; and not by introducing "isogonal transformations" and "vortices," which latter mathematical methods are not essential to the theory and better are used only in papers intended for mathematicians and special experts.
    Keywords: Aerodynamics
    Type: NACA-TR-191
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  • 43
    Publication Date: 2019-06-28
    Description: A method is presented for the estimation of the subsonic-flight-speed characteristics of sharp-lip inlets applicable to supersonic aircraft. The analysis, based on a simple momentum balance consideration, permits the computation of inlet pressure recovery - mass-flow relations and additive-drag coefficients for forward velocities from zero to the speed of sound. The penalties for operation of a sharp-lip inlet at velocity ratios other than 1.0 may be severe; at lower velocity ratios an additive drag is incurred that is not cancelled by lip suction, while at higher velocity ratios, unavoidable losses in inlet total pressure will result. In particular, at the take-off condition, the total pressure and the mass flow for a choked inlet are only 79 percent of the values ideally attainable with a rounded lip. Experimental data obtained at zero speed with a sharp-lip supersonic inlet model were in substantial agreement with the theoretical results.
    Keywords: Aerodynamics
    Type: NACA-TN-3004
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  • 44
    Publication Date: 2019-06-28
    Description: Wake development behind circular cylinders at Reynolds numbers from 40 to 10,000 was investigated in a low-speed wind tunnel. Standard hotwire techniques were used to study the velocity fluctuations. The Reynolds number range of periodic vortex shedding is divided into two distinct subranges. At R = 40 to 150, called the stable range, regular vortex streets are formed and no turbulent motion is developed. The range R = 150 to 300 is a transition range to a regime called the irregular range, in which turbulent velocity fluctuations accompany the periodic formation of vortices. The turbulence is initiated by laminar-turbulent transition in the free layers which spring from the separation points on the cylinder. This transition first occurs in the range R = 150 to 300. Spectrum and statistical measurements were made to study the velocity fluctuations. In the stable range the vortices decay by viscous diffusion. In the irregular range the diffusion is turbulent and the wake becomes fully turbulent in 40 to 50 diameters downstream. It was found that in the stable range the vortex street has a periodic spanwise structure. The dependence of shedding frequency on velocity was successfully used to measure flow velocity. Measurements in the wake of a ring showed that an annular vortex street is developed.
    Keywords: Aerodynamics
    Type: NACA-TN-2913
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  • 45
    Publication Date: 2019-06-28
    Description: A supersonic inlet with supersonic deceleration of the flow entirely outside of the inlet is considered. A particular arrangement with fixed geometry having a central body with a circular annular intake is analyzed, and it is shown theoretically that this arrangement gives high pressure recovery for a large range of Mach number and mass flow and therefore is practical for use on supersonic airplanes and missiles. For some Mach numbers the drag coefficient for this type of inlet is larger than the drag coefficient for the type of inlet with supersonic compression entirely inside, but the pressure recovery is larger for all flight conditions. The differences in drag can be eliminated for the design Mach number. Experimental results confirm the results of the theoretical analysis and show that pressure recoveries of 95 percent for Mach numbers of 1.33 and 1.52, 92 percent for a Mach number of 1.72, and 86 percent for a Mach number of 2.10 are possible, with the configurations considered. If the mass flow decreases, the total drag coefficient increases gradually and the pressure recovery does not change appreciably. The results of this work were first presented in a classified document issued in 1946.
    Keywords: Aerodynamics
    Type: NACA-TN-2286
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  • 46
    Publication Date: 2019-06-28
    Description: The hypersonic similarity law as derived by Tsien has been investigated by comparing the pressure distributions along bodies of revolution at zero angle of attack. In making these comparisons, particular attention was given to determining the limits of Mach number and fineness ratio for which the similarity law applies. For the purpose of this investigation, pressure distributions determined by the method of characteristics for ogive cylinders for values of Mach numbers and fineness ratios varying from 1.5 to 12 were compared. Pressures on various cones and on cone cylinders were also compared in this study. The pressure distributions presented demonstrate that the hypersonic similarity law is applicable over a wider range of values of Mach numbers and fineness ratios than might be expected from the assumptions made in the derivation. This is significant since within the range of applicability of the law a single pressure distribution exists for all similarly shaped bodies for which the ratio of free-stream Mach number to fineness ratio is constant. Charts are presented for rapid determination of pressure distributions over ogive cylinders for any combination of Mach number and fineness ratio within defined limits.
    Keywords: Aerodynamics
    Type: NACA-TN-2250
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  • 47
    Publication Date: 2019-06-28
    Description: No abstract available
    Keywords: Aerodynamics
    Type: NACA-TN-2211
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  • 48
    facet.materialart.
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    In:  CASI
    Publication Date: 2019-06-28
    Description: This report gives the pressure distribution and resistance found by theory and experiment for simple quadrics fixed in an infinite uniform stream of practically incompressible fluid. The experimental values pertain to air and some liquids, especially water; the theoretical refer sometimes to perfect, again to viscid fluids. For the cases treated the concordance of theory and measurement is so close as to make a resume of results desirable. Incidentally formulas for the velocity at all points of the flow field are given, some being new forms for ready use derived in a previous paper. (author)
    Keywords: Aerodynamics
    Type: NACA-TR-253
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  • 49
    Publication Date: 2019-05-11
    Description: Closed-form expressions and tables composed from these expressions are presented for complete and partial conic and spheric bodies at combined angles of attack and sideslip in Newtonian flow. Aerodynamic coefficients of these bodies are tabulated for various body segments over a range of angles of attack from 1 deg to 85 deg and angles of sideslip from 0 deg to 15 deg. Some comparisons between Newtonian predictions and hypersonic experimental aerodynamic characteristics were made for conic bodies hawing various surface slopes, nose bluntnesses, and body cross sections to indicate the range of validity of the theory. In general, the theory is shown to agree quite well with experimental results for sharp-nose complete cones and for configurations hawing large blunted noses and steep surface slopes. However, agreement between theory and experiment generally is poor for the more slender, slightly blunted complete or half conic bodies and also for sharp-nose half conic bodies where real-flow phenomena such as forebody interference, viscous forces, leeward surface contributions, or leading-edge pressure reductions may have significant effect. The agreement between theory and experiment for the bodies considered can be improved by using the stagnation pressure coefficient behind a normal shock rather than 2 as the Newtonian coefficient, although for the sharp-nose half conic bodies there i s no theoretical justification for this modification.
    Keywords: Aerodynamics
    Type: NASA-TR-R-127
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  • 50
    Publication Date: 2018-06-05
    Description: Measurements of average skin friction of the turbulent boundary layer have been made on a 15deg total included angle cone with foreign gas injection. Measurements of total skin-friction drag were obtained at free-stream Mach numbers of 0.3, 0.7, 3.5, and 4.7 and within a Reynolds number range from 0.9 x 10(exp 6) to 5.9 x 10(exp 6) with injection of helium, air, and Freon-12 (CCl2F2) through the porous wall. Substantial reductions in skin friction are realized with gas injection within the range of Mach numbers of this test. The relative reduction in skin friction is in accordance with theory-that is, the light gases are most effective when compared on a mass flow basis. There is a marked effect of Mach number on the reduction of average skin friction; this effect is not shown by the available theories. Limited transition location measurements indicate that the boundary layer does not fully trip with gas injection but that the transition point approaches a forward limit with increasing injection. The variation of the skin-friction coefficient, for the lower injection rates with natural transition, is dependent on the flow Reynolds number and type of injected gas; and at the high injection rates the skin friction is in fair agreement with the turbulent boundary layer results.
    Keywords: Aerodynamics
    Type: Journal of Aerospace Sciences; Volume 27; No. 5; 321-333
    Format: text
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  • 51
    Publication Date: 2018-06-06
    Description: Time varying control of CL is necessary for integrating AFC and Flight Control (Biasing allows for +/- changes in lift) Time delays associated with actuation are long (APPROX.5.8 c/U) and must be included in controllers. Convolution of input signal with single pulse kernel gives reasonable prediction of lift response.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 363-374; NASA/CP-2010-216112
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  • 52
    Publication Date: 2018-06-06
    Description: DNS is a powerful tool with high potential for investigating unsteady heat transfer and fluid flow phenomena, in particular for cases involving transition to turbulence and/or large coherent structures. - DNS of idealized configurations related to turbomachinery components is already possible. - For more realistic configurations and the inclusion of more effects, reduction of computational cost is key issue (e.g., hybrid methods). - Approach pursued here: Embedded DNS ( segregated coupling of DNS with LES and/or RANS). - Embedded DNS is an enabling technology for many studies. - Pre-transitional heat transfer and trailing-edge cutback film-cooling are good candidates for (embedded) DNS studies.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 93-116; NASA/CP-2010-216112
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  • 53
    Publication Date: 2018-06-06
    Description: Exploiting instabilities rather than forcing the flow is advantageous. Simple 2D concepts may not always work. Nonlinear effects may result in first order effect. Interaction between spanwise and streamwise vortices may have a paramount effect on the mean flow, but this interaction may not always be beneficial.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 1-36; NASA/CP-2010-216112
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  • 54
    Publication Date: 2018-06-06
    Description: Broad Flow Control Issues: a) Understanding flow physics. b) Specific control objective(s). c) Actuation. d) Sensors. e) Integrated active flow control system. f) Development of design tools (CFD, reduced order models, controller design, understanding and utilizing instabilities and other mechanisms, e.g., streamwise vorticity).
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 585-587; NASA/CP-2010-216112
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  • 55
    Publication Date: 2018-06-06
    Description: To develop New Flow Control Techniques: a) Knowledge of the Flow Physics with and without control. b) How does Flow Control Effect Flow Physics (What Works to Optimize the Design?). c) Energy or Work Efficiency of the Control Technique (Cost - Risk - Benefit Analysis). d) Supportability, e.g. (size of equipment, computational power, power supply) (Allows Designer to include Flow Control in Plans).
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 349-361; NASA/CP-2010-216112
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  • 56
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    In:  CASI
    Publication Date: 2018-06-06
    Description: Issues & Topics Discussed: a) Aviation Week reported shortfall In LPT efficiency due to the application of "high lift airfoils". b) Progress in the design technologies in LPTs during the last 20 years: 1) Application of RANS based CFD codes. 2) Integration of recent experimental data and modeling of LPT airfoil specific flows into design methods. c) Opportunities to further enhance LPT efficiency for commercial aviation and military transport application and to impact emissions, noise, weight & cost.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 601-604; NASA/CP-2010-216112
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  • 57
    Publication Date: 2018-06-06
    Description: The main objective is to develop effective control strategies for separation control of an airfoil with a single hinge flap. The specific objectives are: Develop an active control architecture for flow control around an airfoil with flap. Design, fabricate, a wind tunnel test of a high lift wing (with flap) with integrated actuators and sensors. Design, development and fabrication of synthetic jet actuators. Develop appropriate control strategy for application to the airfoil. Wind tunnel testing of the high lift wing at various angles of attack and flap positions with closed loop control.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 151-180; NASA/CP-2010-216112
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  • 58
    Publication Date: 2018-06-06
    Description: New ideas are forthcoming to break existing bottlenecks in using CFD during design. CAD-based automated grid generation. Multi-disciplinary use of embedded, overset grids to eliminate complex gridding problems. Use of time-averaged detached-eddy simulations as norm instead of "steady" RANS to include effects of self-excited unsteadiness. Combined GPU/Core parallel computing to provide over an order of magnitude increase in performance/price ratio. Gas-turbine applications are shown here but these ideas can be used for other Air Force, Navy, and NASA applications.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 43-60; NASA/CP-2010-216112
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  • 59
    Publication Date: 2018-06-06
    Description: We finally go back to the four swirl cases and see how the flow responds to either forcing m = -1 or m = -2. On the left we see the flow forced at m = -1 We see that the PVC locks onto the applied forcing also for lower swirl number causing this high TKE at the jet center. The amplification of this instability causes VB to occur at a lower swirl number. The opposite can be seen when forcing the flow at m=-2 which is basically growing in the outer shear layer causing VB to move downstream . There is no energy at the center of the vortex showing that the precessing has been damped. The mean flow is most altered at the swirl numbers were VB is unstable.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 557-583; NASA/CP-2010-216112
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  • 60
    Publication Date: 2018-06-06
    Description: Effects of variable-frequency forcing. Relation to linear theory. Effects of three-dimensional forcing. Relation between instability mechanisms. Future work includes open-loop control and feedback control.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 531-556; NASA/CP-2010-216112
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  • 61
    facet.materialart.
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    In:  CASI
    Publication Date: 2018-06-06
    Description: The details: a) Need stable numerical methods; b) Round off error can be considerable; c) Not convinced modes are correct for incompressible flow. Nonetheless, can derive compact and accurate reduced-order models. Can be used to generate actuator models or full flow-field models
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 495-507; NASA/CP-2010-216112
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  • 62
    facet.materialart.
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    In:  CASI
    Publication Date: 2018-06-06
    Description: Let s start with the report - as you know - when we are talking about flow control it is a multi-disciplinary type of work. So it involves many people and disciplines. This group first discussed the important issues associated with flow control. As you start doing flow control what are the issues to which you really have to start paying attention? That is the first part I am going to present. Then in the second part I will present some challenges - problems that we should really be looking at. So as far as the issues - if you want to control a flow, you really need to understand the flow physics, because anything that you do comes from the flow physics. The design of the controllers, your decisions on the actuators, sensors, reduced order modeling and all of that, would be helped if you understand flow physics. And you have to have a specific objective - what exactly are you controlling? Are you trying to reduce drag, eliminate separation, reduce noise, enhance mixing? So you have to have very specific control objectives. From all the talks we have seen here actuation is extremely important and it is very problem specific. It depends on what problem you are dealing with so you have to design and build actuators for that specific problem. Sensors obviously are very important, especially when you are dealing with feedback control. Consensus was that when you dealing with flow control, you must take an integrated approach; from the beginning you have to take into account every aspect of it and even maybe to modify your experiment, your geometry, to go along with the actuation, sensors and control models. Development of tools is very important in this multi-disciplinary problem. The tools include CFD, reduced order modeling, controller design, understanding and utilizing the instabilities of the flow, etc. So, in order to have success in flow control, we really need to develop these tools.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 623-638; NASA/CP-2010-216112
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  • 63
    Publication Date: 2018-06-06
    Description: HPT blade unsteadiness in the presence of a downstream vane consistent with contra-rotation is characterized by strong interaction at the first harmonic of downstream vane passing. E An existing stage-and-one-half transonic turbine rig design was used as a baseline to investigate means of reducing such a blade-vane interaction. E Methods assessed included: Aerodynamic shaping of HPT blades 3D stacking of the downstream vane Steady pressure-side blowing E Of the methods assessed, a combination of vane bowing and steady pressure-side blowing produced the most favorable result. E Transonic turbine experiments are planned to assess predictive accuracy for the baseline turbine and any design improvements.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 399-416; NASA/CP-2010-216112
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  • 64
    Publication Date: 2018-06-06
    Description: Objectives: Measure the flow structure and turbulence within a Naval, axial waterjet pump. Create a database for benchmarking and validation of parallel computational efforts. Address flow and turbulence modeling issues that are unique to this complex environment. Measure and model flow phenomena affecting cavitation within the pump and its effect on pump performance. This presentation focuses on cavitation phenomena and associated flow structure in the tip region of a rotor blade.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 117-133; NASA/CP-2010-216112
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  • 65
    Publication Date: 2018-06-06
    Description: Structural skeleton of high Reynolds number flow gives insight into smooth and rough walls. (modeling implications not yet clear) Dynamic roughness as a model of "designer" roughness: a) Impose length scale(s) and dominant frequency. b) Irregular roughness well-represented by first "few" POD modes (Christensen, 2009). Experiments and simple model demonstrate: a) Harmonics associated with forcing (and w) important. b) Change to the mean profile (skin friction).
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 259-271; NASA/CP-2010-216112
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  • 66
    Publication Date: 2018-06-06
    Description: Methodology similar to that used for our closed-loop control of Separation over NACA 0012 Airfoil (Pinier et al, AIAA Journal 2007) Synthetic Jet Actuators, Miniature Pressure Transducers Split POD with and without Actuations Flow state estimation from Pressure signature
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 509-529; NASA/CP-2010-216112
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  • 67
    Publication Date: 2018-06-06
    Description: In order to phase lock the flow at the desired shedding cycle, particularly at Phi,best, We designed a feedback compensator. (Even though the open-loop forcing at Wf below Wn can lead to phase-locked limit cycles with a high average lift,) This feedback controller resulted in the phase-locked limit cycles that the open-loop control could not achieve for alpha=30 and 40 Particularly for alpha=40, the feedback was able to stabilize the limit cycle that was not stable with any of the open-loop periodic forcing. This results in stable phase-locked limit cycles for a larger range of forcing frequencies than the open-loop control. Also, it was shown that the feedback achieved the high-lift unsteady flow states that open-loop control could not sustain even after the states have been achieved for a long period of time.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 181-204; NASA/CP-2010-216112
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  • 68
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    In:  CASI
    Publication Date: 2018-06-06
    Description: Open loop edge blowing was demonstrated as an effective method for reducing the broad band and tonal components of the fluctuating surface pressure in open cavities. Closed loop has been successfully applied to low Mach number open cavities. Need to push actuators that are viable for closed loop control in bandwidth and output. Need a better understanding of the effects of control on the flow through detailed measurements so better actuation strategies can be developed.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 289-303; NASA/CP-2010-216112
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  • 69
    Publication Date: 2018-06-06
    Description: Active flow control is often used to manipulate flow instabilities to achieve a desired goal (e.g. prevent separation, enhance mixing, reduce noise, etc.). Instability frequencies normally scale with flow velocity scale and inversely with flow length scale (U/l). In a laboratory setting for such flow experiments, U is high, but l is low, resulting in high instability frequency. In addition, high momentum and high background noise & turbulence in the flow necessitate high amplitude actuation. Developing a high amplitude and high frequency actuator is a major challenge. Ironically, these requirements ease up in application (but other issues arise).
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 135-150; NASA/CP-2010-216112
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  • 70
    Publication Date: 2018-06-06
    Description: Four examples of flow control: 1) Passive control of LP turbine blades (Laminar separation control). 2) Aspiration of a conventional axial compressor blade (Turbulent separation control). 3) Compressor blade designed for aspiration (Turbulent separation control). 4.Control of intakes in crosswinds (Turbulent separation control).
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 435-472; NASA/CP-2010-216112
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  • 71
    Publication Date: 2018-06-06
    Description: Evaluate the efficacy of Microjets Can we eliminate/minimize flow separation? Is the flow unsteadiness reduced? Guidelines for an active control Search for an appropriate sensor. Examine for means to develop a flow model for identifying the state of flow over the surface Guidelines toward future development of a Simple and Robust control methodology
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 375-398; NASA/CP-2010-216112
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  • 72
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2018-06-06
    Description: Environmental issues are a key driver. The need for better mechanisms to enable discipline hopping/crossover (materials (MEMS), control, fluids). Better sensors and actuators and better communication for these to be developed. Better understanding of the needs of the turbomachinery industry, especially in identifying where flow control can be beneficial (e.g., variable intake geometry). Challenge for flow control to be fail-safe, or to be developed for non-critical control gains (e.g., noise). more detailed information on stage through-flow behaviour (with/without control) increased use of laser interrogation (PIV, PTV, MTV).
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 605-621; NASA/CP-2010-216112
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  • 73
    Publication Date: 2018-06-06
    Description: Three existing and two new excitation magnitude scaling options for active separation control at Reynolds numbers below one Million. The physical background for the scaling options was discussed and their relevance was evaluated using two different sets of experimental data. For F+ approx. 1, 2D excitation: a) The traditional VR and C(mu) - do not scale the data. b) Only the Re*C(mu) is valid. This conclusion is also limited for positive lift increment.. For F+ 〉 10, 3D excitation, the Re corrected C(mu), the St corrected velocity ratio and the vorticity flux coefficient, all scale the amplitudes equally well. Therefore, the Reynolds weighted C(mu) is the preferred choice, relevant to both excitation modes. Incidence also considered, using Ue from local Cp.
    Keywords: Aerodynamics
    Type: Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics; 305-347; NASA/CP-2010-216112
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  • 74
    Publication Date: 2019-06-28
    Description: The performance of NACA 65-series compressor blade section in cascade has been investigated systematically in a low-speed cascade tunnel. Porous test-section side walls and for high-pressure-rise conditions, porous flexible end walls were employed to establish conditions closely simulating two-dimensional flow. Blade sections of design lift coefficients from 0 to 2.7 were tested over the usable angle-of-attack range for various combinations of inlet-flow angle. A sufficient number of combinations were tested to permit interpolation and extrapolation of the data to all conditions within the usual range of application. The results of this investigation indicate a continuous variation of blade-section performance as the major cascade parameters, blade camber, inlet angle, and solidity were varied over the test range. Summary curves of the results have been prepared to enable compressor designers to select the proper blade camber and angle of attack when the compressor velocity diagram and desired solidity have been determined.
    Keywords: Aerodynamics
    Type: NACA-TR-1368 , NACA-RM-L51G31
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  • 75
    Publication Date: 2019-06-28
    Description: This report is based on a study made by the writer as a member of the Special Committee on Design of Army Semirigid Airship RS-1 appointed by the National Advisory Committee for Aeronautics. The increasing interest in airships has made the problem of the potential flow of a fluid about an ellipsoid of considerable practical importance. In 1833 George Green, in discussing the effect of the surrounding medium upon the period of a pendulum, derived three elliptic integrals, in terms of which practically all the characteristics of this type of motion can be expressed. The theory of this type of motion is very fully given by Horace Lamb in his "Hydrodynamics," and applications to the theory of airships by many other writers. Tables of the inertia coefficients derived from these integrals are available for the most important special cases. These tables are adequate for most purposes, but occasionally it is desirable to know the values of these integrals in other cases where tabulated values are not available. For this reason it seems worth while to assemble a collection of formulae which would enable them to be computed directly from standard tables of elliptic integrals, circular and hyperbolic functions and logarithms without the need of intermediate transformations. Some of the formulae for special cases (elliptic cylinder, prolate spheroid, oblate spheroid, etc.) have been published before, but the general forms and some special cases have not been found in previous publications. (author)
    Keywords: Aerodynamics
    Type: NACA-TR-210
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  • 76
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-06-28
    Description: The design of complicated structures often presents problems of extreme difficulty which are frequently insoluble. In many cases, however, the solution can be obtained by tests on suitable models. These model tests are becoming so important a part of the design of new engineering structures that their theory has become a necessary part of an engineer's knowledge. For balloons and airships water models are used. These are models about 1/30 the size of the airship hung upside down and filled with water under pressure. The theory shows that the stresses in such a model are the same as in the actual airship. In the design of the Army Semirigid Airship RS-1 no satisfactory way was found to calculate the stresses in the keel due to the changing shape of the bag. For this purpose a water model with a flexible keel was built and tested. This report gives the theory of the design, construction, and testing of such a water model.
    Keywords: Aerodynamics
    Type: NACA-TR-211
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  • 77
    Publication Date: 2019-06-28
    Description: In the first article, in connection with a lecture on the hydrodynamic basis of flight and the potential flow about a Joukowski wing, the pressure distribution on several wings is computed and plotted. The diagrams of the pressure distributions are presented accompanied with a qualitative discussion of the pressure distribution. In the second article, the the cross-sectional outline (or profile) a Joukowski wing are plotted.
    Keywords: Aerodynamics
    Type: NACA-TM-336
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  • 78
    Publication Date: 2019-06-28
    Description: The aerodynamic effects of fixing boundary-layer transition for a swept- and a triangular-wing configuration have been determined from tests of two small-scale wing-body models. The wings had an aspect ratio of 2.99 and 3-percent-thick biconvex sections. Lift, pitching-moment, and drag data were obtained at Mach numbers ranging from 0.60 to 1.40 for angles of attack between -2 deg and about 15 deg. The Reynolds number of the tests was generally 1.5 million; however, minimum drag measurements were made for both models over a range of Reynolds numbers from 1.0 million to about 3.0 or 4.0 million.
    Keywords: Aerodynamics
    Type: NASA-TN-D-312
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  • 79
    Publication Date: 2019-06-28
    Description: A theoretical analysis indicates that, for rotors, ground effect decreases rapidly with increases in either height above the ground or forward speed. The decrease with height above the ground in forward flights is greater than that in hovering. The major part of the decrease in ground effect with forward speed occurs at speeds less than 1.5 times the hovering mean induced velocity. Consequently, the total induced velocity at the rotor center increases rather than decreases when a helicopter gathers speed at low height above the ground.
    Keywords: Aerodynamics
    Type: NASA-TN-D-234
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  • 80
    Publication Date: 2019-06-27
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: N. Am. Aviation Proc. of the 12th Lunar and Planetary Exploration Colloq., Vol. 3, No. 2; p 9-28
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  • 81
    Publication Date: 2019-06-27
    Description: An investigation of the isothermal wake-flow characteristics of several flame-holder shapes was carried out in a 4- by 4-inch flow chamber. The effects of flame-holder-shape changes on the characteristics of the Karman vortices and thus on the recirculation zones to which experimenters have related the combustion process were obtained for several flame holders. The results may furnish a basis of correlation, of combustion efficiency and stability for similarly shaped flame holders in combustion studies. Values of the spacing ratio-(ratio of lateral spacing to longitudinal spacing of vortices] obtained for the various shapes approximated the theoretical value of 0.36 given by the Karman stability analysis. Variations in vortex strength of more than 200 percent and in frequency of more than 60 percent were accomplished by varying flame-holder shape. A maximum increase in the recirculation parameter of 56 percent over that for a conventional V-gutter was also obtained. Varying flameholder shape and size enables the designer to select many schedules of variations in vortex strength and frequency- not obtainable by changing size only and may make it possible to approach theoretical maximum vortex strength for any given frequency.
    Keywords: Aerodynamics
    Type: NACA-RM-E51K07 , E-2403
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  • 82
    Publication Date: 2019-07-27
    Description: In response to the fourth AIAA CFD Drag Prediction Workshop (DPW-IV), the NASA Common Research Model (CRM) wing-body and wing-body-tail configurations are analyzed using the Reynolds-averaged Navier-Stokes (RANS) flow solvers CFL3D and OVERFLOW. Two families of structured, overset grids are built for DPW-IV. Grid Family 1 (GF1) consists of a coarse (7.2 million), medium (16.9 million), fine (56.5 million), and extra-fine (189.4 million) mesh. Grid Family 2 (GF2) is an extension of the first and includes a superfine (714.2 million) and an ultra-fine (2.4 billion) mesh. The medium grid anchors both families with an established build process for accurate cruise drag prediction studies. This base mesh is coarsened and enhanced to form a set of parametrically equivalent grids that increase in size by a factor of roughly 3.4 from one level to the next denser level. Both CFL3D and OVERFLOW are run on GF1 using a consistent numerical approach. Additional OVERFLOW runs are made to study effects of differencing scheme and turbulence model on GF1 and to obtain results for GF2. All CFD results are post-processed using Richardson extrapolation, and approximate grid-converged values of drag are compared. The medium grid is also used to compute a trimmed drag polar for both codes.
    Keywords: Aerodynamics
    Type: AIAA Paper 2010-4219 , NF1676L-10897 , 28th AIAA Applied Aerodynamics Conference; 28 Jun. 1 Jul. 2010; Chicago, IL; United States
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  • 83
    Publication Date: 2019-07-27
    Description: No abstract available
    Keywords: Aerodynamics
    Type: 1961 International Heat Transfer Conference; 1961 Aug. 28-Sept. 1; Boulder, CO; United States
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  • 84
    Publication Date: 2019-06-25
    Description: An investigation has been made to study the effect of ground proximity on the aerodynamic characteristics of two jet vertical-take-off-and-landing airplane models in which the fuselage remains in a horizontal attitude for the take-off and landing. The first model (called the tilt-wing model) had a tilting wing-engine assembly which was set at 90 deg incidence for the take-off and landing. The second model, called the deflected-jet model) had a cascade of retractable turning vanes to deflect the exhaust of the horizontally mounted jet engines downward for vertical take-off and landing while the entire model remained in a horizontal attitude. With the models at various heights above the ground in the take-off and landing configuration, the lift, drag, and pitching moment were measured and tuft surveys were made to determine the flow field caused by the jet exhaust. The tilt-wing model experienced a loss of lift of less than 3 percent near the ground. The deflected-jet model, however, suffered losses in lift as high as 45 percent near the ground because of a low pressure region under the model caused by the entrainment of air by the jet exhaust as it spread out along the ground. This loss in lift for the deflected-jet configuration could probably be reduced to less than 5 percent by the use of a longer landing gear and a high wing location.
    Keywords: Aerodynamics
    Type: NASA-TN-D-419 , L-1059
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  • 85
    Publication Date: 2019-07-27
    Description: An Aeroelastic Prediction Workshop (AePW) was held in April 2012 using three aeroelasticity case study wind tunnel tests for assessing the capabilities of various codes in making aeroelasticity predictions. One of these case studies was known as the HIRENASD model that was tested in the European Transonic Wind Tunnel (ETW). This paper summarizes the development of a standardized enhanced analytical HIRENASD structural model for use in the AePW effort. The modifications to the HIRENASD finite element model were validated by comparing modal frequencies, evaluating modal assurance criteria, comparing leading edge, trailing edge and twist of the wing with experiment and by performing steady and unsteady CFD analyses for one of the test conditions on the same grid, and identical processing of results.
    Keywords: Aerodynamics
    Type: AIAA Paper 2013-1801 , NF1676L-15290 , 54th AIAA/ASME/ASCE/AHS/ASC, Structures, Structural Dynamics, and Materials Conference; 8-1` Apr. 2013; Boston, MA; United States
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  • 86
    Publication Date: 2019-07-27
    Description: A source-term model that simulates the effects of vortex generators was implemented into the Wind-US Navier-Stokes code. The source term added to the Navier-Stokes equations simulates the lift force that would result from a vane-type vortex generator in the flowfield. The implementation is user-friendly, requiring the user to specify only three quantities for each desired vortex generator: the range of grid points over which the force is to be applied and the planform area and angle of incidence of the physical vane. The model behavior was evaluated for subsonic flow in a rectangular duct with a single vane vortex generator, subsonic flow in an S-duct with 22 corotating vortex generators, and supersonic flow in a rectangular duct with a counter-rotating vortex-generator pair. The model was also used to successfully simulate microramps in supersonic flow by treating each microramp as a pair of vanes with opposite angles of incidence. The validation results indicate that the source-term vortex-generator model provides a useful tool for screening vortex-generator configurations and gives comparable results to solutions computed using gridded vanes.
    Keywords: Aerodynamics
    Type: AIAA Paper 2010-0032 , E-17922 , AIAA Journal; 49; 4; 748-759|48th AIAA Aerospace Sciences Meeting; 4?7 Jan. 2010; Orlando, FL; United States
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  • 87
    Publication Date: 2019-07-27
    Description: Nonlinear parabolized stability equations and secondary instability analyses are used to provide a computational assessment of the potential use of the discrete roughness elements (DRE) technology for extending swept-wing natural laminar flow at chord Reynolds numbers relevant to transport aircraft. Computations performed for the boundary layer on a natural laminar flow airfoil with a leading-edge sweep angle of 34.6deg, free-stream Mach number of 0.75 and chord Reynolds numbers of 17 x 10(exp 6), 24 x 10(exp 6) and 30 x 10(exp 6) suggest that DRE could delay laminar-turbulent transition by about 20% when transition is caused by stationary crossflow disturbances. Computations show that the introduction of small wavelength stationary crossflow disturbances (i.e., DRE) also suppresses the growth of most amplified traveling crossflow disturbances.
    Keywords: Aerodynamics
    Type: AIAA Paper 2013-0412 , NF1676L-14855 , 51st AIAA Aerospace Sciences Meeting; 7-110 Jan. 2013; Grapevine, TX; United States
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  • 88
    Publication Date: 2019-06-27
    Description: No abstract available
    Keywords: Aerodynamics
    Type: NASA-TM-X-57072
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  • 89
    Publication Date: 2019-06-27
    Description: An investigation has been conducted in the Langley 20-foot free spinning tunnel to study the relative behavior in descent of a number of homogeneous balsa bodies of revolution simulating anti-personnel bombs with a small cylindrical exploding device suspended approximately 10 feet below the bomb. The bodies of revolution included hemispherical, near-hemispherical, and near-paraboloid shapes. The ordinates of one near-paraboloid shape were specified by the Office of the Chief of Ordnance, U. S. Army. The behavior of the various bodies without the cylinder was also investigated. The results of the investigation indicated that several of the bodies descended vertically with their longitudinal axis, suspension line, and small cylinder in a vertical attitude,. However, the body, the ordinates of which had been specified by the Office of the Chief of Ordnance, U. S. Army, oscillated considerably from a vertical attitude while descending and therefore appeared unsuitable for its intended use. The behavior of this body became satisfactory when its center of gravity was moved well forward from its original position. In general, the results indicated that the descent characteristics of the bodies of revolution become more favorable as their shapes approached that of a hemisphere.
    Keywords: Aerodynamics
    Type: NACA-RM-SL51L13
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  • 90
    Publication Date: 2019-07-13
    Description: Separated flow over a bluff body is analyzed via large eddy simulations. The turbulent flow around a square cylinder features a variety of complex flow phenomena such as highly unsteady vortical structures, reverse flow in the near wall region, and wake turbulence. The formation of spanwise vortices is often times artificially suppressed in computations by either insufficient depth or a coarse spanwise resolution. As the resolution is refined and the domain extended, the artificial turbulent energy exchange between spanwise and streamwise turbulence is eliminated within the wake region. A parametric study is performed highlighting the effects of spanwise vortices where the spanwise computational domain's resolution and depth are varied. For Re=22,000, the mean and turbulent statistics computed from the numerical large eddy simulations (NLES) are in good agreement with experimental data. Von-Karman shedding is observed in the wake of the cylinder. Mesh independence is illustrated by comparing a mesh resolution of 2 million to 16 million. Sensitivities to time stepping were minimized and sampling frequency sensitivities were nonpresent. While increasing the spanwise depth and resolution can be costly, this practice was found to be necessary to eliminating the artificial turbulent energy exchange.
    Keywords: Aerodynamics
    Type: AIAA Paper 2014-2089 , E-663992 , AIAA Fluid Dynamics Conference; Jun 16, 2014 - Jun 20, 2014; Atlanta, GA; United States
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  • 91
    Publication Date: 2019-07-13
    Description: Fundamental research for sonic boom reduction is needed to quantify the interaction of shock waves generated from the aircraft wing or tail surfaces with the nozzle exhaust plume. Aft body shock waves that interact with the exhaust plume contribute to the near-field pressure signature of a vehicle. The plume and shock interaction was studied using computational fluid dynamics and compared with experimental data from a coaxial convergent-divergent nozzle flow in an open jet facility. A simple diamond-shaped wedge was used to generate the shock in the outer flow to study its impact on the inner jet flow. Results show that the compression from the wedge deflects the nozzle plume and shocks form on the opposite plume boundary. The sonic boom pressure signature of the nozzle exhaust plume was modified by the presence of the wedge. Both the experimental results and computational predictions show changes in plume deflection.
    Keywords: Aerodynamics
    Type: E-663895 , AIAA SciTech 2014; Jan 13, 2014 - Jan 17, 2014; National Harbor, MD; United States
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  • 92
    Publication Date: 2019-07-13
    Description: We discuss thrust measurements of Dielectric Barrier Discharge (DBD) plasma actuators devices used for aerodynamic active flow control. After a review of our experience with conventional thrust measurement and significant non-repeatability of the results, we devised a suspended actuator test setup, and now present a methodology of thrust measurements with decreased uncertainty. The methodology consists of frequency scans at constant voltages. The procedure consists of increasing the frequency in a step-wise fashion from several Hz to the maximum frequency of several kHz, followed by frequency decrease back down to the start frequency of several Hz. This sequence is performed first at the highest voltage of interest, then repeated at lower voltages. The data in the descending frequency direction is more consistent and selected for reporting. Sample results show strong dependence of thrust on humidity which also affects the consistency and fluctuations of the measurements. We also observed negative values of thrust or "anti-thrust", at low frequencies between 4 Hz and up to 64 Hz. The anti-thrust is proportional to the mean-squared voltage and is frequency independent. Departures from the parabolic anti-thrust curve are correlated with appearance of visible plasma discharges. We propose the anti-thrust hypothesis. It states that the measured thrust is a sum of plasma thrust and anti-thrust, and assumes that the anti-thrust exists at all frequencies and voltages. The anti-thrust depends on actuator geometry and materials and on the test installation. It enables the separation of the plasma thrust from the measured total thrust. This approach enables more meaningful comparisons between actuators at different installations and laboratories. The dependence on test installation was validated by surrounding the actuator with a large diameter, grounded, metal sleeve.
    Keywords: Aerodynamics
    Type: AIAA Paper 2014-0486 , E-18857-1 , AIAA SciTech 2014; Jan 13, 2014 - Jan 17, 2014; National Harbor, MD; United States
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  • 93
    Publication Date: 2019-07-13
    Description: Determining the adverse aerodynamic effects due to ice accretion often relies on dry-air wind-tunnel testing of artificial, or simulated, ice shapes. Recent developments in ice accretion documentation methods have yielded a laser-scanning capability that can measure highly three-dimensional features of ice accreted in icing wind tunnels. The objective of this paper was to evaluate the aerodynamic accuracy of ice-accretion simulations generated from laser-scan data. Ice-accretion tests were conducted in the NASA Icing Research Tunnel using an 18-inch chord, 2-D straight wing with NACA 23012 airfoil section. For six ice accretion cases, a 3-D laser scan was performed to document the ice geometry prior to the molding process. Aerodynamic performance testing was conducted at the University of Illinois low-speed wind tunnel at a Reynolds number of 1.8 x 10(exp 6) and a Mach number of 0.18 with an 18-inch chord NACA 23012 airfoil model that was designed to accommodate the artificial ice shapes. The ice-accretion molds were used to fabricate one set of artificial ice shapes from polyurethane castings. The laser-scan data were used to fabricate another set of artificial ice shapes using rapid prototype manufacturing such as stereolithography. The iced-airfoil results with both sets of artificial ice shapes were compared to evaluate the aerodynamic simulation accuracy of the laser-scan data. For four of the six ice-accretion cases, there was excellent agreement in the iced-airfoil aerodynamic performance between the casting and laser-scan based simulations. For example, typical differences in iced-airfoil maximum lift coefficient were less than 3% with corresponding differences in stall angle of approximately one degree or less. The aerodynamic simulation accuracy reported in this paper has demonstrated the combined accuracy of the laser-scan and rapid-prototype manufacturing approach to simulating ice accretion for a NACA 23012 airfoil. For several of the ice-accretion cases tested, the aerodynamics is known to depend upon the small, three dimensional features of the ice. These data show that the laser-scan and rapid-prototype manufacturing approach is capable of replicating these ice features within the reported accuracies of the laser-scan measurement and rapid-prototyping method; thus providing a new capability for high-fidelity ice-accretion documentation and artificial ice-shape fabrication for icing research.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN14961 , AIAA Atmospheric and Space Environments Conference; Jun 16, 2014 - Jun 20, 2014; Atlanta, GA; United States
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  • 94
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-07-13
    Description: Reliable prediction of contra-rotating open rotor (CROR) noise is an essential element of any strategy for the development of low-noise open rotor propulsion systems that can meet both the community noise regulations and the cabin noise limits. Since CROR noise spectra typically exhibits a preponderance of tones, significant efforts have been directed towards predicting their tone spectra. To that end, there has been an ongoing effort at NASA to assess various in-house open rotor tone noise prediction tools using a benchmark CROR blade set for which significant aerodynamic and acoustic data had been acquired in wind tunnel tests. In the work presented here, the focus is on the near-field noise of the benchmark open rotor blade set at the cruise condition. Using an analytical CROR tone noise model with input from high-fidelity aerodynamic simulations, detailed tone noise spectral predictions have been generated and compared with the experimental data. Comparisons indicate that the theoretical predictions are in good agreement with the data, especially for the dominant CROR tones and their overall sound pressure level. The results also indicate that, whereas individual rotor tones are well predicted by the linear sources (i.e., thickness and loading), for the interaction tones it is essential that the quadrupole sources be included in the analysis.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN15607 , AIAA/CEAS Aeroacoustics Conference; Jun 16, 2014 - Jun 20, 2014; Atlanta, GA; United States
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  • 95
    Publication Date: 2019-07-13
    Description: Several minimum-mass aeroelastic optimization problems are solved to evaluate the effectiveness of a variety of novel tailoring schemes for subsonic transport wings. Aeroelastic strength and panel buckling constraints are imposed across a variety of trimmed maneuver loads. Tailoring with metallic thickness variations, functionally graded materials, composite laminates, tow steering, and distributed trailing edge control effectors are all found to provide reductions in structural wing mass with varying degrees of success. The question as to whether this wing mass reduction will offset the increased manufacturing cost is left unresolved for each case.
    Keywords: Aerodynamics
    Type: NF1676L-17757 , AIAA Aviation and Aeronautics Forum and Exposition (AVIATION 2014); Jun 16, 2014 - Jun 20, 2014; Atlanta, GA; United States
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  • 96
    Publication Date: 2019-07-13
    Description: This paper presents results from computational fluid dynamic (CFD) simulations of a three-stream plug nozzle. Time-accurate, Euler, quasi-1D and 2D-axisymmetric simulations were performed as part of an effort to provide a CFD-based approach to modeling nozzle dynamics. The CFD code used for the simulations is based on the space-time Conservation Element and Solution Element (CESE) method. Steady-state results were validated using the Wind-US code and a code utilizing the MacCormack method while the unsteady results were partially validated via an aeroacoustic benchmark problem. The CESE steady-state flow field solutions showed excellent agreement with solutions derived from the other methods and codes while preliminary unsteady results for the three-stream plug nozzle are also shown. Additionally, a study was performed to explore the sensitivity of gross thrust computations to the control surface definition. The results showed that most of the sensitivity while computing the gross thrust is attributed to the control surface stencil resolution and choice of stencil end points and not to the control surface definition itself.Finally, comparisons between the quasi-1D and 2D-axisymetric solutions were performed in order to gain insight on whether a quasi-1D solution can capture the steady and unsteady nozzle phenomena without the cost of a 2D-axisymmetric simulation. Initial results show that while the quasi-1D solutions are similar to the 2D-axisymmetric solutions, the inability of the quasi-1D simulations to predict two dimensional phenomena limits its accuracy.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN16144 , AIAA Joint Propulsion Conference; Jul 28, 2014 - Jul 30, 2014; Cleveland, OH; United States
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  • 97
    Publication Date: 2019-07-13
    Description: Supersonic inlets with external compression, having a good level performance at the critical operating point, exhibit a marked instability of the flow in some subcritical operation below a critical value of the capture mass flow ratio. This takes the form of severe oscillations of the shock system, commonly known as "buzz". The underlying purpose of this study is to indicate how Detached Eddy Simulation (DES) analysis of supersonic inlets will alter how we envision unsteady inlet aerodynamics, particularly inlet buzz. Presented in this paper is a discussion regarding the physical explanation underlying inlet buzz as indicated by DES analysis. It is the normal shock wave boundary layer separation along the spike surface which reduces the capture mass flow that is the controlling mechanism which determines the onset of inlet buzz, and it is the aerodynamic characteristics of a choked nozzle that provide the feedback mechanism that sustains the buzz cycle by imposing a fixed mean corrected inlet weight flow. Comparisons between the DES analysis of the Lockheed Martin Corporation (LMCO) N+2 inlet and schlieren photographs taken during the test of the Gulfstream Large Scale Low Boom (LSLB) inlet in the NASA 8x6 ft. Supersonic Wind Tunnel (SWT) show a strong similarity both in turbulent flow field structure and shock wave formation during the buzz cycle. This demonstrates the value of DES analysis for the design and understanding of supersonic inlets.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN15470 , Joint Propulsion Conference; Jul 28, 2014 - Jul 30, 2014; Cleveland, OH; United States
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  • 98
    Publication Date: 2019-07-13
    Description: A second wind tunnel test of the FAST-MAC circulation control semi-span model was recently completed in the National Transonic Facility at the NASA Langley Research Center. The model allowed independent control of four circulation control plenums producing a high momentum jet from a blowing slot near the wing trailing edge that was directed over a 15% chord simple-hinged flap. The model was configured for transonic testing of the cruise configuration with 0deg flap deflection to determine the potential for drag reduction with the circulation control blowing. Encouraging results from analysis of wing surface pressures suggested that the circulation control blowing was effective in reducing the transonic drag on the configuration, however this could not be quantified until the thrust generated by the blowing slot was correctly removed from the force and moment balance data. This paper will present the thrust removal methodology used for the FAST-MAC circulation control model and describe the experimental measurements and techniques used to develop the methodology. A discussion on the impact to the force and moment data as a result of removing the thrust from the blowing slot will also be presented for the cruise configuration, where at some Mach and Reynolds number conditions, the thrust-removed corrected data showed that a drag reduction was realized as a consequence of the blowing.
    Keywords: Aerodynamics
    Type: AIAA Paper-2014-2402 , NF1676L-17629 , AIAA Applied Aerodynamics Conference; Jun 16, 2014 - Jun 20, 2014; Atlanta, GA.; United States
    Format: application/pdf
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  • 99
    Publication Date: 2019-07-13
    Description: The continued design, certification and safe operation of swept-wing airplanes in icing conditions rely on the advancement of computational and experimental simulation methods for higher fidelity results over an increasing range of aircraft configurations and performance, and icing conditions. The current stateof- the-art in icing aerodynamics is mainly built upon a comprehensive understanding of two-dimensional geometries that does not currently exist for fundamentally three-dimensional geometries such as swept wings. The purpose of this report is to describe what is known of iced-swept-wing aerodynamics and to identify the type of research that is required to improve the current understanding. Following the method used in a previous review of iced-airfoil aerodynamics, this report proposes a classification of swept-wing ice accretion into four groups based upon unique flowfield attributes. These four groups are: ice roughness, horn ice, streamwise ice and spanwise-ridge ice. In the case of horn ice it is shown that a further subclassification of "nominally 3D" or "highly 3D" horn ice may be necessary. For all of the proposed ice-shape classifications, relatively little is known about the three-dimensional flowfield and even less about the effect of Reynolds number and Mach number on these flowfields. The classifications and supporting data presented in this report can serve as a starting point as new research explores swept-wing aerodynamics with ice shapes. As further results are available, it is expected that these classifications will need to be updated and revised.
    Keywords: Aerodynamics
    Type: NASA/TM-2013-216556 , E-18753 , GRC-E-DAA-TN9727 , AIAA Atmospheric and Space Enviroments Conference; Jun 24, 2013 - Jun 27, 2013; San Diego, CA; United States
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  • 100
    Publication Date: 2019-07-13
    Description: NASA, FAA, ONERA, the University of Illinois and Boeing have embarked on a significant, collaborative research effort to address the technical challenges associated with icing on large-scale, three-dimensional swept wings. The overall goal is to improve the fidelity of experimental and computational simulation methods for swept-wing ice accretion formation and resulting aerodynamic effect. A seven-phase research effort has been designed that incorporates ice-accretion and aerodynamic experiments and computational simulations. As the baseline, full-scale, swept-wing-reference geometry, this research will utilize the 65% scale Common Research Model configuration. Ice-accretion testing will be conducted in the NASA Icing Research Tunnel for three hybrid swept-wing models representing the 20%, 64% and 83% semispan stations of the baseline-reference wing. Three-dimensional measurement techniques are being developed and validated to document the experimental ice-accretion geometries. Artificial ice shapes of varying geometric fidelity will be developed for aerodynamic testing over a large Reynolds number range in the ONERA F1 pressurized wind tunnel and in a smaller-scale atmospheric wind tunnel. Concurrent research will be conducted to explore and further develop the use of computational simulation tools for ice accretion and aerodynamics on swept wings. The combined results of this research effort will result in an improved understanding of the ice formation and aerodynamic effects on swept wings. The purpose of this paper is to describe this research effort in more detail and report on the current results and status to date. 1
    Keywords: Aerodynamics
    Type: NASA/TM-2013-216555 , AIAA Paper 2013-28 , E-18752 , GRC-E-DAA-TN9726 , AIAA Atmospheric and Space Enviroment Conference; Jun 24, 2013 - Jun 27, 2013; San Diego, CA; United States
    Format: application/pdf
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