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  • 1
    Publication Date: 2006-03-27
    Description: Full-scale ground tests of an externally blown flap system were made using the wing of an F-111B airplane and a CF700 engine. Pressure and temperature distributions were determined on the undersurface of the wing, vane, and flap for two engine exhaust nozzles (conical and daisy) at several engine power and engine/wing positions. The tests were made with no airflow over the wing. The leading-edge wing sweep angle was fixed at 26 deg, the angle of incidence between the engine and the wing was fixed at 3 deg, and the tests were conducted with the flap retracted, extended and deflected 35 deg, and extended and deflected 60 deg. The integrated local pressures on the undersurface of the flap produced loads approximately three times as great at the 60 deg flap position as at the 35 deg flap position. With both nozzle configurations, more than 90 percent of the integrated pressure loads were contained within plus or minus 20 percent of the flap span centered around the engine exhaust centerline. The maximum temperature recorded on the flaps was 218 C (424 F) for the conical nozzle and 180 C (356 F) for the daisy nozzle.
    Keywords: AERODYNAMICS
    Type: STOL Technol.; p 143-156
    Format: text
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  • 2
    Publication Date: 2013-08-31
    Description: The changes in stability and control characteristics encountered by a thrust reversing aircraft during its final approach, landing, and ground roll are described. These changes include a strong pitch-up accompanied by the loss of horizontal tail and aileron control effectiveness. The magnitude of reverser induced changes in ground effect are much larger than corresponding changes in free air. Some unexpected unsteady motions exhibited in wind tunnel by an aircraft model with reversers operating in ground proximity are also described. The cause of this oscillatory behavior was determined to be an unsteady interaction between the wall jets formed by impingement of reverser jets on the ground and the on-coming free stream. Time histories of rolling moments measured by the wind tunnel balance or support system were removed and frequencies were scaled by Strouhal number to full scale. Corrected time series were used to simulate the motion of a fighter aircraft with thrust reversers in ground effect. The simulation predicted large roll angles and nose down attitude at touchdown. Some phenomena of jet attachment to solid surfaces are discussed and areas for future research are recommended.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Research Center Proceedings of the 1985 NASA Ames Research Center's Ground-Effects Workshop; p 239-288
    Format: application/pdf
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  • 3
    Publication Date: 2011-08-19
    Description: An overview of a new finite element method for the compressible Euler and Navier-Stokes equations is presented. The discretization is based on entropy variables. The method is developed within the framework of a Petrov-Galerkin formulation. Two perturbations are added to the weighting function; one is a generalization of the SUPG operator and the other is designed to enhance shock capturing capability. The treatment of boundary conditions and the consistent calculation of boundary fluxes are addressed. Results of numerical tests are presented which confirm the robustness and wide applicability of the method.
    Keywords: AERODYNAMICS
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  • 4
    Publication Date: 2019-06-28
    Description: An FEM for the compressible Navier-Stokes equations is introduced. The discretization is based on entropy variables. The methodology is developed within the framework of a Galerkin/least-squares formulation to which a discontinuity-capturing operator is added. Results for three test cases selected among those of the Workshop on Hypersonic Flows for Reentry Problems are presented.
    Keywords: AERODYNAMICS
    Type: In: Hypersonic flows for reentry problems. Vol. 2 (A93-42576 17-02); p. 181-200.
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  • 5
    Publication Date: 2019-06-28
    Description: A finite element method for the compressible Navier-Stokes equations is introduced. The discretization is based on entropy variables. The methodology is developed within the framework of a Galerkin/least-squares formulation to which a discontinuity-capturing operator is added. Results for four test cases selected among those of the Workshop on Hypersonic Flows for Reentry Problems are presented.
    Keywords: AERODYNAMICS
    Type: In: Hypersonic flows for reentry problems. Vol. 2 (A93-42576 17-02); p. 427-450.
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  • 6
    Publication Date: 2019-06-28
    Description: The low speed aerodynamic performance characteristics of several advanced counterrotation pusher propeller configurations with cruise design Mach numbers of 0.72 and 0.80 were investigated in the NASA Low Speed Wind Tunnel. The tests were conducted at Mach numbers representative of the takeoff and landing flight regime. The investigation included: (1) the propeller performance characteristics over a range of blade angle settings and rotational speeds at a Mach number of 0.20; (2) the effect on the propeller performance of varying the axial rotor spacing and mismatching the power and rotational speeds on the propeller rotors; and (3) determining the reverse thrust performance characteristics at Mach numbers of 0.0, 0.10, 0.15 and 0.20. The results of the investigation indicated that the overall low speed performance of the counterrotation propeller configurations was reasonable.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 88-3149
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  • 7
    Publication Date: 2019-06-28
    Description: The low speed aerodynamic performance characteristics of several advanced counterrotation pusher propeller configurations with cruise design Mach numbers of 0.72 and 0.80 were investigated in the NASA Low Speed Wind Tunnel. The tests were conducted at Mach numbers representative of the takeoff and landing flight regime. The investigation included: (1) the propeller performance characteristics over a range of blade angle settings and rotational speeds at a Mach number of 0.20; (2) the effect on the propeller performance of varying the axial rotor spacing and mismatching the power and rotational speeds on the propeller rotors; (3) determining the reverse thrust performance characteristics at Mach numbers of 0.0, 0.10, 0.15 and 0.20. The results of the investigation indicated that the overall low speed performance of the counterrotation propeller configurations was reasonable.
    Keywords: AERODYNAMICS
    Type: NASA-TM-100945 , E-4234 , NAS 1.15:100945 , AIAA PAPER 88-3149
    Format: application/pdf
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  • 8
    Publication Date: 2019-06-28
    Description: The low-speed aerodynamic performance characteristics of two advanced counterrotation pusher-propeller configurations with cruise design Mach numbers of 0.72 were investigated in the NASA Lewis 9- by 15-Foot Low-Speed Wind Tunnel. The tests were conducted at Mach number 0.20, which is representative of the aircraft take/off/landing flight regime. The investigation determined the effect of nonuniform inflow on the propeller performance characteristics for several blade angle settings and a range of rotational speeds. The inflow was varied by yawing the propeller mode to angle-of-attack by as much as plus or minus 16 degrees and by installing on the counterrotation propeller test rig near the propeller rotors a model simulator of an aircraft engine support pylon and fuselage. The results of the investigation indicated that the low-speed performance of the counterrotation propeller configurations near the take-off target operating points were reasonable and were fairly insensitive to changes in model angle-of-attack without the aircraft pylon/fuselage simulators installed on the propeller test rig. When the aircraft pylon/fuselage simulators were installed, small changes in propeller performance were seen at zero angle-of-attack, but fairly large changes in total power coefficient and very large changes of aft-to-forward-rotor torque ratio were produced when the propeller model was taken to angle-of-attack. The propeller net efficiency, though, was fairly insensitive to any changes in the propeller flowfield conditions near the take-off target operating points.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 89-2583
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  • 9
    Publication Date: 2019-06-28
    Description: Rehabilitation and extention of the capability of the altitude wind tunnel (AWT) was analyzed. The analytical modelling program involves the use of advanced axisymmetric and three dimensional viscous analyses to compute the flow through the various AWT components. Results for the analytical modelling of the high speed leg aerodynamics are presented; these include: an evaluation of the flow quality at the entrance to the test section, an investigation of the effects of test section bleed for different model blockages, and an examination of three dimensional effects in the diffuser due to reentry flow and due to the change in cross sectional shape of the exhaust scoop.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 85-0380
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  • 10
    Publication Date: 2019-06-27
    Description: Flow phenomena of the F-111A air intake system were investigated over a large range of Mach number, altitude, and angle of attack. Boundary-layer variations are shown for the fuselage splitter plate and inlet entrance stations. Inlet performance is shown in terms of pressure recovery, airflow, mass-flow ratio, turbulence factor, distortion factor, and power spectral density. The fuselage boundary layer was found to be not completely removed from the upper portion of the splitter plate at all Mach numbers investigated. Inlet boundary-layer ingestion started at approximately Mach 1.6 near the translating spike and cone. Pressure-recovery distribution at the compressor face showed increasing distortion with increasing angle of attack and increasing Mach number. The time-averaged distortion-factor value approached 1300, which is near the distortion tolerance of the engine at Mach numbers above 2.1.
    Keywords: AERODYNAMICS
    Type: NASA-TN-D-6679 , H-661
    Format: application/pdf
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