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  • AERODYNAMICS  (449)
  • Life and Medical Sciences  (266)
  • FLUID MECHANICS AND HEAT TRANSFER
  • GENERAL
  • 1975-1979  (798)
  • 1955-1959  (71)
  • 1940-1944  (57)
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  • 1
    Publikationsdatum: 2011-08-17
    Beschreibung: Steady state solutions to two time dependent partial differential systems have been obtained by the Method of Lines (MOL) and compared to those obtained by efficient standard finite difference methods: (1) Burger's equation over a finite space domain by a forward time central space explicit method, and (2) the stream function - vorticity form of viscous incompressible fluid flow in a square cavity by an alternating direction implicit (ADI) method. The standard techniques were far more computationally efficient when applicable. In the second example, converged solutions at very high Reynolds numbers were obtained by MOL, whereas solution by ADI was either unattainable or impractical. With regard to 'set up' time, solution by MOL is an attractive alternative to techniques with complicated algorithms, as much of the programming difficulty is eliminated.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Computers and Fluids; 6; June 197
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2016-06-07
    Beschreibung: Results from recent investigations in the Langley V/STOL tunnel of an externally blown flap and an upper surface blown flap configuration in ground proximity are presented. Comparisons of longitudinal aerodynamic characteristics indicate that in ground proximity, drag is reduced for both configurations, but changes in lift are configuration dependent. Steady state analyses of the landing approach indicate an increase in flight path angle for both configurations in ground proximity because of the drag reduction. Dynamic analyses with a fixed-base simulator indicate that the resultant flight path during landing approach is dependent on the initial flight path angle and the control technique used.
    Schlagwort(e): AERODYNAMICS
    Materialart: Powered-Lift Aerodyn. and Acoustics; p 145-158
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2019-06-27
    Beschreibung: Results of engineering analyses assessing the conceptual feasibility of a large capacity heat pump for enhancing active cooling of hypersonic aircraft structure are presented. A unique heat pump arrangement which permits cooling the structure of a Mach 6 transport to aluminum temperatures without the aid of thermal shielding is described. The selected concept is compatible with the use of conventional refrigerants, with Freon R-11 selected as the preferred refrigerant. Condenser temperatures were limited to levels compatible with the use of conventional refrigerants by incorporating a unique multipass condenser design, which extracts mechanical energy from the hydrogen fuel, prior to each subsequent pass through the condenser. Results show that it is technically feasible to use a large capacity heat pump in lieu of external shielding. Additional analyses are required to optimally apply this concept.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA-CR-145301
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2019-06-27
    Beschreibung: A combined experimental and computational research program is described for testing and guiding turbulence modeling within regions of separation induced by shock waves incident in turbulent boundary layers. Specifically, studies are made of the separated flow the rear portion of an 18%-thick circular-arc airfoil at zero angle of attack in high Reynolds number supercritical flow. The measurements include distributions of surface static pressure and local skin friction. The instruments employed include highfrequency response pressure cells and a large array of surface hot-wire skin-friction gages. Computations at the experimental flow conditions are made using time-dependent solutions of ensemble-averaged Navier-Stokes equations, plus additional equations for the turbulence modeling.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA-TM-X-73157 , A-6690
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    facet.materialart.
    Unbekannt
    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: An investigation of the transonic flow over a circular arc airfoil was conducted to obtain basic information for turbulence modeling of shock-induced separated flows and to verify numerical computer codes which are being developed to simulate such flows. The investigation included the employment of a laser velocimeter to obtain data concerning the mean velocity, the shear stress, and the turbulent kinetic energy profiles in the flowfield downstream of the airfoil midchord where the flow features are more complex. Depending on the free-stream Mach number, the flowfield developed was either steady with shock-wave-induced separation extending from the foot of the shock wave to beyond the trailing edge or unsteady with a periodic motion also undergoing shock-induced separation. The experimental data were compared with the results of numerical simulations in which a computer code was employed that solved the time-dependent Reynolds' averaged compressible Navier-Stokes equations.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA PAPER 78-160 , Aerospace Sciences Meeting; Jan 16, 1978 - Jan 18, 1978; Huntsville, AL
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Publikationsdatum: 2019-07-13
    Beschreibung: A combined experimental and computational research program for testing and guiding turbulence modeling within regions of separation induced by shock waves incident on turbulent boundary layers is described. Specifically, studies are made of the separated flow over the rear portion of an 18%-thick circular-arc airfoil at zero angle of attack in high Reynolds number supercritical flow. The measurements include distributions of surface static pressure and local skin friction. The instruments employed include high-frequency response pressure cells and a large array of surface hot-wire skin-friction gages. Computations at the experimental flow conditions are made using time-dependent solutions of ensemble-averaged Navier-Stokes equations, plus additional equations for the turbulence modeling.
    Schlagwort(e): AERODYNAMICS
    Materialart: ICAS PAPER 76-15 , Congress; Oct 03, 1976 - Oct 08, 1976; Ottawa; Canada
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 2019-07-13
    Schlagwort(e): AERODYNAMICS
    Materialart: SAE PAPER 750703 , West Coast Meeting; Aug 11, 1975 - Aug 14, 1975; Seattle, WA
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    facet.materialart.
    Unbekannt
    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: A detailed examination of the turbulent field in an unsteady transonic flow undergoing shock-induced separation is conducted. Ensemble-averaged mean and fluctuating velocities, obtained from conditionally sampled laser velocimeter data, are described and analyzed to assess the applicability of modeling concepts usually employed in steady-flow problems. Some comparisons with computations employing the Reynolds averaged Navier-Stokes equations with a mixing length turbulence model are then presented to illustrate the status of current predictive capabilities. The results appear to imply that turbulence models developed for steady flows apply and that the model need not reflect all the fine details of the turbulent structure but rather account in an approximate way for the production and destruction of the turbulence.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA PAPER 79-0071 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 69 (1941), S. 537-561 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 152 (1977), S. 1-19 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Records of electrical activity in the tracheal muscles of domestic chickens were obtained for a variety of ad libitum vocalizations. Primary attention was given to an analysis of events during the most complex call, crowing.Three pairs of muscles, Mm. tracheohyoideus, tracheolateralis, and sternotrachealis, can affect the configuration of a chicken's syrinx. The firing patterns of the three muscle pairs are related to their different abilities to affect the tension of the syringeal membranes. The influence of M. tracheohyoideus is most indirect and imprecise, and its role the least clearly defined. It appears to adjust the position of the trachea so that the syrinx is isolated from unpredictable and/or undesirable consequences of nuchal position and tracheal elasticity, and also helps draw the glottis caudad, thereby deepening the pharyngeal chamber. The other two muscles interact to control the tension of the vocal membranes. M. sternotrachealis relaxes the membranes by drawing the drum of the trachea caudad, or, via the syringeal ligament, by rotating the pessulus cranioventrad, or both. M. tracheolateralis tenses the membranes and/or prevents caudal movement of the origin of M. sternotrachealis, a necessity if the syringeal ligament is to rotate the pessulus.Vocalization depends on both syringeal configuration and appropriate air flow. Hence, tracheal muscles, syrinx, air sacs, and ventilatory muscles cooperate to form a vocal system. Cooperation elicits a surprising degree of redundancy. At least one call, a high pitched wail, may be produced by two very different techniques.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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