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Results for “MACH NUMBER EFFECTS - PROPELLERS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Flight and wind-tunnel measurements showing base drag reduction provided by a trailing disk for high Reynolds number turbulent flow for subsonic and transonic Mach numbers

The effectiveness of a trailing disk, or trapped vortex concept, in reducing the base drag of a large body of revolution was studied from measurements made both in flight and in a wind tunnel. Pressure data obtained for the flight experiment, and both pressure and force balance data were obtained for the wind tunnel experiment. The flight test also included data obtained from a hemispherical base. The experiment demonstrated the significant base drag reduction capability of the trailing disk to Mach 0.93 and to Reynolds numbers up to 80 times greater than for earlier studies. For the trailing disk data from the flight experiment, the maximum decrease in base drag ranged form 0.08 to 0.07 as Mach number increased from 0.70 to 0.93. Aircraft angles of attack ranged from 3.9 to 6.6 deg for the flight data. For the trailing disk data from the wind tunnel experiment, the maximum decrease in base and total drag ranged from 0.08 to 0.05 for the approximately 0 deg angle of attack data as Mach number increased from 0.30 to 0.82.

Powers, Sheryll Goecke↗
NASA NTRS1992

Secondary instability of high-speed flows and the influence of wall cooling and suction

The periodic streamwise modulation of the supersonic and hypersonic boundary layers by a two dimensional first mode or second mode wave makes the resulting base flow susceptible to a broadband spanwise-periodic three dimensional type of instability. The principal parametric resonance of this instability (subharmonic) was analyzed using Floquet theory. The effect of Mach number and the effectiveness of wall cooling or wall suction in controlling the onset, the growth rate, and the vortical nature of the subharmonic secondary instability are assessed for both a first mode and a second mode primary wave. Results indicate that the secondary subharmonic instability of the insulated wall boundary layer is weakened as Mach number increases. Cooling of the wall destabilizes the secondary subharmonic of a second mode primary wave, but stabilizes it when the primary wave is a first mode. Suction stabilizes the secondary subharmonic at all Mach numbers.

El-Hady, Nabil M.↗
NASA NTRS1992

Secondary instability of high-speed flows and the influence of wall cooling and suction

The periodic streamwise modulation of the supersonic and hypersonic boundary layers by a two-dimensional first-mode or second-mode wave makes the resulting base flow susceptible to a broadband spanwise-periodic three-dimensional type of instability. The principal parametric resonance of this instability (subharmonic) has been analyzed using Floquet theory. The effect of Mach number and the effectiveness of wall cooling or wall suction in controlling the onset, the growth rate, and the vortical structure of the subharmonic secondary instability are assessed for both a first-mode and a second-mode primary wave. Results indicate that the secondary subharmonic instability of an insulated wall boundary layer is weakened as Mach number increases. Cooling of the wall destabilizes the secondary subharmonic of a second-mode primary wave, but stabilizes it when the primary wave is a first mode. Suction stabilizes the secondary subharmonic at all Mach numbers.

El-Hady, Nabil M.↗
NASA NTRS1972

Results of a study of Mach number and Reynolds number effects on the lee side vortex flow field characteristics of an ogive-cylinder-frustum-cylinder at angles of attack to 25 degrees, volume 1

An experimental program was conducted to survey the lee side vortex flow field about an ogive-cylinder-frustum-cylinder at angles of attack to 25 degrees for two Reynolds numbers at Mach number 0.8, and one Reynolds number at Mach number 1.96. The data were obtained using miniature 5-port conical pressure probes calibrated for angle of attack and roll angle over a Mach number range of 0.6 to 3.0. The results are presented here as local flow field properties and circulation strengths for various body stations.

Foley, J. E.↗
NASA NTRS1951

Lift, Drag, and Pitching Moment of Low-aspect-ratio Wings at Subsonic and Supersonic Speeds : Twisted and Cambered Triangular Wing of Aspect Ratio 2 with NACA 0003-63 Thickness Distribution

This report presents the results of an investigation to ascertain the lift, drag, and pitching moment of a wing-body combination having a triangular wing of aspect ratio 2 with NACA 0003-63 thickness distribution in streamwise planes and twisted and cambered for a nearly elliptical span load distribution. Results are shown for Mach numbers from 0.60 to 0.90 and from 1.30 to 1.70 at Reynolds numbers of 3.0 million and 7.5 million.

WINGS, COMPLETE - DESIGN VARIABLES↗
NASA NTRS1990

Total temperature effects on centerline Mach number characteristics of freejets

This paper describes a detailed experimental study of Mach number centerline characteristics of unheated and heated freejets. The jet characteristics were obtained at a range of jet Mach numbers from 0.1 to 0.9 and jet total temperatures up to 900 K. Previously published results showed that the jet total temperature significantly affects the nozzle-exit, boundary-layer characteristics. The results of this study indicate that a strong correlation exists between nozzle-exit, boundary-layer conditions and freejet development. It is clear from this investigation that experimental data on freejet development cannot be meaningfully compared from one facility to another without specific knowledge of nozzle-exit, boundary-layer conditions. It was concluded that direct effect of the jet operating conditions (elevated flow temperature) on freejet development is much less important than the indirect effect due to changed nozzle-exit, boundary-layer characteristics.

Lepicovsky, J.↗
NASA NTRS1972

Results of a study of Mach number and Reynolds number effects on the lee side vortex flow field characteristics of an ogive-cylinder-frustum-cylinder at angles of attack to 25 degrees. Volume 2: Appendix

A listing of the data reduction computer program output for the analysis of the lee side vortex flow about an ogive-cylinder-frustum-cylinder is presented. A computed local flow property for the flow field location array at a specific body station and freestream condition is listed. Significant local flow properties are computed. The local circulation strengths in the radial and circumferential directions are analyzed.

Foley, J. E.↗
NASA NTRS1973

Mach number and Reynolds number effect on orbiter/tank interference heating.

Analysis of the variations in orbiter/tank interference heating rates in the Space Shuttle configuration at M numbers up to 19 and Re numbers down to 250,000. Experimental data on heat transfer rate distribution in the tank and on orbiter-induced interference heat transfer factors in the tank are included in diagrams. The data suggest that the primary effect of interference can be a fully developed turbulent boundary layer.

Creel, T. R., Jr.↗
NASA NTRS1991

Effect of convective Mach number on mixing of coaxial circular and rectangular jets

Rectangular supersonic free and coaxial jets were used to enhance mixing relative to a circular jet in a convective Mach number range of 0.5 to 2.2. The different convective Mach numbers were obtained by changing the central jet gas composition, the temperatures of the inner and outer flows, and the velocity of the coaxial flow. The experimental techniques used were schlieren photography, total pressure, and gas-sampling measurements. For all test conditions the rectangular jets showed substantial improved mixing relative to a circular jet. The free jets showed high mixing in the circumferential region of the jet while the coaxial jet had a high mixing rate inside the central jet.

Gutmark, E.↗
NASA NTRS1991

Secondary instability of high-speed flows and the influence of wall cooling and suction

The periodic streamwise modulation of the supersonic and hypersonic boundary layers by a two-dimensional first-mode or second-mode wave makes the resulting base flow susceptible to a broad-band spanwise-periodic three-dimensional type of instability. The principal parametric resonance of this instability (subharmonic) has been analyzed using Floquet theory. The effect of Mach number and the effectiveness of wall cooling or wall suction in controlling the onset, the growth rate, and the vortical structure of the subharmonic secondary instability are assessed for both a first-mode and a second-mode primary wave.

El-Hady, Nabil M.↗
NASA NTRS1991

The effect of varying Mach number on crossing, glancing shocks/turbulent boundary-layer interactions

Two crossing side-wall shocks interacting with a supersonic tunnel wall boundary layer have been investigated over a Mach number range of 2.5 to 4.0. The investigation included a range of equal shock strengths produced by shock generators at angles from 4.0 to 12.0 degrees. Results of flow visualization show that the interaction is unseparated at the low shock generator angles. With increasing shock strength, the flow begins to form a separated region that grows in size and moves forward and eventually the model unstarts. The wall static pressures show a symmetrical compression that merges on the centerline upstream of the inviscid shock locations and becomes more 1D downstream. The region of the 1D pressure gradient moves upstream with increasing shock strengths until it coincides with the leading edge of the shock generators at the limit before model unstart. At the limiting conditions the wall pressure gradients are primarily in the axial direction throughout.

Hingst, W. R.↗