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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 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
NASA NTRS1958

Free-Flight Investigation of Aerodynamic Heat Transfer to a Simulated Glide-Rocket Shape at Mach Numbers up to 10

Heat-transfer measurements were made on a simulated glide-rocket shape in free flight at Mach numbers up to 10 and free-stream Reynolds numbers of 2 x 10 based on distance along surface from apex and 3 x 10 based on nominal leading-edge diameter. The model simulated the bottom of a 75 deg delta wing at 8O deg angle of attack. The data indicated that for the test conditions a modified three-dimensional stagnation-point theory will predict to reasonable engineering accuracy the heating on a highly swept wing leading edge, the heating being reduced by sweep by the 3/2 power of the cosine of the sweep angle. The data also indicate that laminar heating rates over the windward surface of a highly swept flat glider wing at moderate angles of attack can be predicted with reasonable engineering accuracy by flat-plate theory using wedge local flow conditions and basing Reynolds numbers on lengths from the wing leading edge parallel to the surface center line.

FREE FLIGHT↗
NASA NTRS1958

Aerodynamic characteristics at mach numbers from 2.5 to 3.5 of a canard bomber configuration designed for supersonic cruise flight

Resilts have been obtained from an investigation in the Langley Unitary Plan wind tunnel at Mach numbers from 2.5 to 3.5 of a canard-type configuration designed for supersonic cruise flight. Tests extended over an angle-of-attack range from about -4 deg to 11 deg and an angle-of-sideslip range from -4 deg to 6 deg. For the present tests, the results indicate that forebody deflection was an efficient means of providing a sizable positive pitching-moment shift with little or no increase in drag. The test configuration had a trimmed lift-drag ratio of approximately 6.0 at Mach numbers near 3.0 and at a Reynolds number of 2.52 X 10(exp 6). The configuration was both longitudinally and directionally stable. The lift-drag ratios are believed to be somewhat low in as much as the models used for the present tests had large-grain size transition strips fixed to the various surfaces and these strips added wave drag. Also, the model boundary-layer diverter is oversized with respect to a full-scale configuration and therefore contributes additional drag.

Carmel, M. M.↗
NASA NTRS1957

Free-Flight Skin Temperature and Pressure Measurements on a Slightly Blunted 25 Deg Cone-Cylinder-Flare Configuration to a Mach Number of 9.89

Skin temperatures and surface pressures have been measured on a slightly blunted cone-cylinder-flare configuration to a maximum Mach number of 9.89 with a rocket-propelled model. The cone had a t o t a l angle of 25 deg and the flare had a 10 deg half-angle. Temperature data were obtained at eight cone locations, four cylinder locations, and seven flare locations; pressures were measured at one cone location, one cylinder location, and three flare locations. Four stages of propulsion were utilized and a reentry type of trajectory was employed in which the high-speed portion of flight was obtained by firing the last two stages during the descent of the model from a peak altitude of 99,400 feet. The Reynolds number at peak Mach number was 1.2 x 10(exp 6) per foot of model length. The model length was 6.68 feet. During the higher speed portions of flight, temperature measurements along one element of the nose cone indicated that the boundary layer was probably laminar, whereas on the opposite side of the nose the measurements indicated transitional or turbulent flow. Temperature distributions along one meridian of the model showed the flare to have the highest temperatures and the cylinder generally to have the lowest. A maximum temperature of 970 F was measured on the cone element showing the transitional or turbulent flow; along the opposite side of the model, the maximum temperatures of the cone, cylinder, and flare were 545 F, 340 F, and 680 F, respectively, at the corresponding time.

Bond, Aleck C.↗
NASA NTRS1971

Aerodynamic characteristics of an all-body hypersonic aircraft configuration at Mach numbers from 0.65 to 10.6

Aerodynamic characteristics of a model designed to represent an all body, hypersonic cruise aircraft are presented for Mach numbers from 0.65 to 10.6. The configuration had a delta planform with an elliptic cone forebody and an afterbody of elliptic cross section. Detailed effects of varying angle of attack (-2 to +15 deg), angle of sideslip (-2 to +8 deg), Mach number, and configuration buildup were considered. In addition, the effectiveness of horizontal tail, vertical tail, and canard stabilizing and control surfaces was investigated. The results indicate that all configurations were longitudinally stable near maximum lift drag ratio. The configurations with vertical tails were directionally stable at all angles of attack. Trim penalties were small at hypersonic speeds for a center of gravity location representative of the airplane, but because of the large rearward travel of the aerodynamic center, trim penalties were severe at transonic Mach numbers.

Nelms, W. P., Jr.↗
NASA NTRS1972

Effects of body shape on the aerodynamic characteristics of an all-body hypersonic aircraft configuration at Mach numbers from 0.65 to 10.6

An experimental investigation was conducted to determine the effects of several variations in body shape on the aerodynamic characteristics of an all-body hypersonic aircraft configuration. The basic configuration had a delta planform with an elliptic cone forebody and an afterbody of elliptic cross section terminating in a straight-line trailing edge. Variations in body shape included the ratio of maximum cross-sectional to body planform area, body leading-edge sweep, and forebody length ratio. In addition, the effects of a thin wing mounted on one of the bodies was investigated, and the aerodynamic characteristics of just the forebodies of two of the configurations were determined. The models had no stabilizing surfaces or propulsion system packages. Ranges of angle of attack (-4 deg to +15 deg) and angle of sideslip (-4 deg to +8 deg) were investigated. Of the four complete bodies, the configuration with the lowest ratio of cross-sectional to body planform area had the highest maximum lift-drag ratio and the greatest level of longitudinal stability at most Mach numbers. All the configurations had positive longitudinal stability near maximum lift-drag ratio at most Mach numbers. With exception of the lowest subsonic Mach numbers, changes in body sweep angle and in forebody length ratio had only minor effects on maximum lift-drag ratio.

Nelms, W. P., Jr.↗
NASA NTRS1970

Static and dynamic pitching moment measurements on a family of elliptic cones at Mach number 11 in helium

Static and dynamic pitching moment measurements were made on a family of constant volume elliptic cones about two fixed axes of oscillation in the NAE helium hypersonic wind tunnel at a Mach number of 11 and at Reynolds numbers based on model length of up to 14 million. Viscous effects on the stability derivatives were investigated by varying the Reynolds number for certain models by a factor as large as 10. The models investigated comprised a 7.75 deg circular cone, elliptic cones of axis ratios 3 and 6, and an elliptic cone with conical protuberances.

Orlik-Rueckermann, K. J.↗
NASA NTRS1972

Wind tunnel measurements of surface pressure fluctuations at Mach numbers of 1.6, 2.0, and 2.5 using 12 different transducers

The turbulent boundary layer on the wall of a 9 by 7 foot wind tunnel was measured with 12 different transducers at Mach numbers of 1.6, 2.0, and 2.5. The results indicated that the wall surface-pressure-fluctuation field was more homogeneous at a Mach number of 2.5 than at Mach numbers of 1.6 or 2.0. A comparison of power-spectral-density data at Mach 2.5 with a summary of similar data (Mach 0.1 to 3.45) showed good agreement. The measurement uncertainty was greatest when frequencies were low and the surface-pressure-fluctuation field was homogeneous. The uncertainty at higher frequencies increased as the surface-pressure-fluctuation field became more inhomogeneous. Since transducer mounting effects and system noise levels were determined not to have contributed appreciably to measurement uncertainties, the result was attributed to an interaction between the surface-pressure-fluctuation field and the transducers. Corcos' correction for size effects improved the comparison between transducers at the high frequencies, but did not eliminate an apparent size effect at the lower frequencies.

Lewis, T. L.↗
NASA NTRS1972

Experimental evaluation of the aerodynamic damping of skin panels at low supersonic Mach numbers.

The aerodynamic damping of the first three vibration modes of a rectangular panel exposed to an attached turbulent boundary layer has been measured over the Mach number range of 1.10 to 1.40. Data showing that aerodynamic damping is a strong function of Mach number, dynamic pressure, mode shape, and boundary layer thickness are presented. At low supersonic Mach numbers, aerodynamic damping was found to be 20 to 100 times as large as common values of structural damping. Means of calculating aerodynamic damping, including effects of the boundary layer profile, are discussed. Calculated aerodynamic damping is compared with experimental data.

Muhlstein, L., Jr.↗
NASA NTRS1962

Comparison of the Effectiveness of Flares With That of Fins for Stabilizing Low Fineness Ratio Bodies at Mach Numbers From 0.6 to 5.8

An experimental and analytical investigation has been made of the effectiveness of flares and of fins for providing aerodynamic stability of low-fineness-ratio bodies near zero angle of attack. Wind-tunnel tests were performed at Mach numbers from 0.6 to 3.8 to measure the normal force, center of pressure, and drag of bodies consisting of conical noses in combination with cylindrical midsections and finned or flared aftersections. This study included an investigation of the effects of nose bluntness, midbody length, flare angle (from 0° to 20°), and fin leading-edge bluntness. The results showed that for the same plan-form area, flares were more effective than fins, but for the same drag, fins were more effective than flares. Flow separation, which occurred ahead of a flare at certain Mach numbers, resulted in an increase in the stabilizing effectiveness of the flare and a decrease in the drag. However, flow separation led to large undesirable shifts in the center of pressure. Blunt fins were found to be more effective than sharp fins, with the vertical as well as the horizontal fins contributing to the effectiveness. Comparisons of the analytical with the experimental results indicated that the analytical method employed gave good estimates of the stabilizing effectiveness of both fins and flares throughout the supersonic Mach number range.

Leland H Jorgensen↗
NASA NTRS1972

Assessment of a transitional boundary layer theory at low hypersonic Mach numbers

An investigation was carried out to assess the accuracy of a transitional boundary layer theory in the low hypersonic Mach number regime. The theory is based upon the simultaneous numerical solution of the boundary layer partial differential equations for the mean motion and an integral form of the turbulence kinetic energy equation which controls the magnitude and development of the Reynolds stress. Comparisions with experimental data show the theory is capable of accurately predicting heat transfer and velocity profiles through the transitional regime and correctly predicts the effects of Mach number and wall cooling on transition Reynolds number. The procedure shows promise of predicting the initiation of transition for given free stream disturbance levels. The effects on transition predictions of the pressure dilitation term and of direct absorption of acoustic energy by the boundary layer were evaluated.

Shamroth, S. J.↗
NASA NTRS1972

Experimental aerodynamic characteristics of 120 deg included-angle cone with attached and separated 20 deg included-angle cone at Mach numbers of 2.36 and 2.70

An investigation has been conducted in a unitary plan wind tunnel to determine the aerodynamic characteristics of two different size blunt 120 deg-included-angle cones behind a 20 deg-included-angle cone. Forces and moments were measured at Mach numbers of 2.36 and 2.70, longitudinal separation distances from 0 to 3.5 body diameters, lateral (side) distances from 0 to 0.50 body diameter, angles of attack of the 120 deg-included-angle cone from 0.5 deg to 22 deg, angles of attack of the 20 deg-included-angle cone from 0 deg to 180 deg, and a Reynolds number of one million per foot. Large variations in pitching-moment, normal-force, and axial-force coefficients were noted for both Mach numbers and all longitudinal distances for the 120 deg cones in the wake of a 20 deg cone.

Brown, C. A., Jr.↗
NASA NTRS1973

Separation over a flat plate-wedge configuration at oceanic Reynolds numbers

An experimental study of flow over a two-dimensional flat plate-wedge configuration is presented. The investigation encompasses a range of Reynolds numbers characteristics of conditions encountered by deep submersible oceanic vehicles. Flow separation, similar to that found on high speed aircraft control surfaces, is reported and discussed in light of the laminar or transitional nature of the separated shear layer. As discovered in previous high Mach number studies of plate-wedge or ramp configurations, the dependency of the size of the separated region on free stream Reynolds number is reversed for laminar and transitional types of flow separation.

Campbell, D. R.↗
NASA NTRS1973

Analytic and experimental performance of two isentropic mixed compression axisymmetric inlets at Mach numbers 0.8 to 2.65

A mixed compression axisymmetric inlet model with a capture diameter of 50 cm was tested at Mach numbers ranging from 0.8 to 2.65 at 0 deg angle of attack and a constant total pressure of approximately 1 atm. Analytical methods accounting for the effects of both viscous and inviscid flows and incorporating empirical bleed discharge coefficients were used in the procedure for designing the inlet contours and the bleed system. Experimental results are compared with analytic predictions and are also compared with results from earlier tests of an inlet with the same internal contours but with a bleed system developed by cut and try methods in the wind tunnel. With the bleed configuration predicted by the design procedure, maximum total pressure recovery at the engine face at the design Mach number of 2.65 was 93 percent, with a total pressure distortion less than 10 percent. Corresponding bleed mass flow was approximately 7.5 percent, which was about 1.3 percent less than predicted. At lower supersonic Mach numbers, pressure recovery and bleed were generally lower and distortion generally higher.

Smeltzer, D. B.↗
NASA NTRS1973

The restoration of obliterated stamped serial numbers by ultrasonically induced cavitation in water

Seventeen out of 21 obliterated stamped serial numbers on test specimens of copper, brass, steel, and aluminum were successfully restored. Cavitation induced in water by a piezoelectric transducer was the mechanism used. Primarily, smeared metal was removed from the number grooves by the force of the cavitation, however, numbers were also restored at depths at or below the level of the stamped grooves. The feasibility of this technique as a low cost tool for crime laboratories has been clearly demonstrated. The technique is applicable to a variety of materials, and no previous surface or chemical treatments are necessary.

Young, S. G.↗
NASA NTRS1972

Effect of Reynolds number and engine nacelles on the stalling characteristics of a model of a twin-engine light airplane

The investigation was made on a 1/18-scale model of a twin-engine light airplane. Static longitudinal, lateral, and directional characteristics were obtained at 0 deg and plus or minus 5 deg sideslip at a Mach number of about 0.2. The angle of attack varied from about 20 deg at a Reynolds number of 0.39 times one million to 13 deg at a Reynolds number of 3.7 times one million, based on the reference chord. The effect of fixed transition, vertical and horizontal tails, and nacelle fillets was studied.

Lockwood, V. E.↗
NASA NTRS1973

Effect of inlet-air humidity, temperature, pressure, and reference Mach number on the formation of oxides of nitrogen in a gas turbine combustor

Tests were conducted to determine the effect of inlet air humidity on the formation of oxides of nitrogen (NOx) from a gas turbine combustor. Combustor inlet air temperature ranged from 506 K (450 F) to 838 K (1050 F). The tests were primarily run at a constant pressure of 6 atmospheres and reference Mach number of 0.065. The NOx emission index was found to decrease with increasing inlet air humidity at a constant exponential rate: NOx = NOx0e-19H (where H is the humidity and the subscript 0 denotes the value at zero humidity). the emission index increased exponentially with increasing normalized inlet air temperature to the 1.14 power. Additional tests made to determine the effect of pressure and reference Mach number on NOx showed that the NOx emission index varies directly with pressure to the 0.5 power and inversely with reference Mach number.

Marchionna, N. R.↗
NASA NTRS1973

Experimental wake survey behind Viking 75 entry vehicle at angles of attack of 0 deg, 5 deg, and 10 deg, Mach numbers from 0.20 to 1.20, and longitudinal stations from 1.50 to 11.00 body diameters

An investigation was conducted to obtain flow properties in the wake of a preliminary configuration of the Viking '75 Entry Vehicle at Mach numbers from 0.20 to 1.20 and at angles of attack of 0 deg, 5 deg, and 10 deg. The wake flow properties were calculated from total and static pressures measured with a pressure rake at longitudinal stations varying from 1.50 to 11.00 body diameters, and are presented in tabulated and plotted form. The wake properties were essentially symmetrical about the X-axis at alpha = 0 deg and the profiles were shifted away from the X-axis at angles of attack. An unexpected reduction in wake property ratios occurred as the Mach number increased from 0.60 to 1.00; these ratios then increased as the Mach number increased to 1.20. The reduction was present for all the longitudinal stations of the tests and decreased with increased longitudinal distance.

Brown, C. A., Jr.↗
NASA NTRS1974

An investigation of several NACA 1 series axisymmetric inlets at Mach numbers from 0.4 to 1.29

An investigation was conducted in the Langley 16-foot transonic tunnel to determine the performance of seven inlets having NACA 1-series contours and one inlet having an elliptical contour over a range of mass-flow ratios and at angle of attack. The inlet diameter ratio varied from 0.81 to 0.89; inlet length ratio varied from 0.75 to 1.25; and internal contraction ratio varied from 1.009 to 1.093. Reynolds number based on inlet maximum diameter varied from 3.4 million at a Mach number of 0.4 to 5.6 million at a Mach number of 1.29.

Re, R. J.↗