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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Exploratory investigation of lift induced on a swept wing by a two-dimensional partial-span deflected jet at Mach numbers from 0.20 to 1.30

An exploratory investigation was conducted in the Langley 16-foot transonic tunnel at Mach numbers from 0.20 to 1.30 to determine the induced lift characteristics of a body and swept-wing configuration having a partial-span two-dimensional propulsive nozzle with exhaust exit in the notch of the swept-wing trailing edge. The Reynolds number per meter varied from 4,900,000 to 14,030,000. The effects on wing-body characteristics of deflecting the propulsive jet in the flap mode at nominal exhaust-nozzle deflection angles of 0 deg and 30 deg were studied for two nozzle designs with different geometry and wing spans.

Capone, F. J.↗
NASA NTRS1972

Aerodynamic characteristics of a swept augmentor wing

A brief outline of augmentor wing research is presented and is followed by a discussion of large scale wind tunnel test results for a swept augmentor wing configuration. The results show that the augmentor wing can be applied to high speed swept wing designs with little adverse effect on either the basic performance of the augmentor or the longitudinal characteristics, including maximum lift and stall. Three lateral control devices were shown to be effective and ground effect was measured for several complete aircraft configurations.

Koenig, D. G.↗
NASA NTRS1972

Aerodynamic characteristics of a swept augmentor wing

A brief outline of augmentor wing research sponsored by Ames Research Center is presented and is followed by a discussion of large-scale wind-tunnel test results for a swept augmentor wing configuration. The results showed that the augmentor wing could be applied to high-speed swept wing designs with little adverse effect on either the basic performance of the augmentor or the longitudinal characteristics, including maximum lift and stall. Three lateral control devices were shown to be effective and ground effect was measured for several complete aircraft configurations.

Koenig, D. G.↗
NASA NTRS1974

Investigation of the three-dimensional turbulent flow downstream of swept slot injection in hypersonic flow

Results of an experimental and numerical investigation of tangential swept slot injection (sweep angles of 22.5 and 45 deg) into a thick turbulent boundary layer at Mach 6 are presented. Film cooling effectiveness, skin friction, and flow structure downstream of the swept slot injection are investigated. The data are compared to that for unswept slots, and it is found that cooling effectiveness and skin-friction reductions are not significantly affected by sweeping the slot. Predictions of cooling effectiveness and skin friction obtained by a numerical finite-difference technique agree reasonably well with experimental surface variables. As in previous supersonic two-dimensional slot research, reduced mixing was found downstream of the slot lip in the present three-dimensional case.

Hefner, J. N.↗
NASA NTRS1974

An experimental and theoretical study of low-aspect ration swept and oblique wings at Mach numbers between 0.6 and 1.4

Experimental forces and moments for two wing-body combinations having (a) a swept wing and (b) an oblique wing are compared. At all Mach numbers, the oblique wing (at its optimum sweep angle) had higher maximum lift-to-drag ratios than the fixed, swept wing. At high angles of attack, the direction of the pitching or rolling tendencies of the oblique wing was a function of the spanwise distribution of wing bend or washout for the two bends being investigated. At low angles of attack, linear theory gave satisfactory predictions of the subsonic lift-curve slope, the aerodynamic-center travel with Mach number, and the maximum lift-to-drag ratio.

Hopkins, E. J.↗
NASA NTRS1975

Velocity and rolling-moment measurements in the wake of a swept-wing model in the 40 by 80 foot wind tunnel

Measurements were made in the wake of a swept wing model to study the structure of lift generated vortex wakes shed by conventional span loadings and by several span loadings designed to reduce wake velocities. Variations in the span loading on the swept wing generator were obtained by deflecting seven flap segments on each side by amounts determined by vortex lattice theory to approximate the desired span loadings. The resulting wakes were probed with a three component, hot wire probe to measure velocity, and with a wing to measure the rolling moment that would be induced on a following aircraft. The experimental techniques are described herein, and the measured velocity and rolling moments are presented, along with some comparisons with the applicable theories.

Rossow, V. J.↗
NASA NTRS1975

Experimental investigation of a Mach 6 fixed-geometry inlet featuring a swept external-internal compression flow field

An investigation of a fixed-geometry, swept external-internal compression inlet was conducted at a Mach number of 6.0 and a test-section Reynolds number of 1.55 x 10 to the 7th power per meter. The test conditions was constant for all runs with stagnation pressure and temperature at 20 atmospheres and 500 K, respectively. Tests were made at angles of attack of -5 deg, 0 deg, 3 deg, and 5 deg. Measurements consisted of pitot- and static-pressure surveys in inlet throat, wall static pressures, and surface temperatures. Boundary-layer bleed was provided on the centerbody and on the cowl internal surface. The inlet performance was consistently high over the range of the angle of attack tested, with an overall average total pressure recovery of 78 percent and corresponding adiabatic kinetic-energy efficiency of 99 percent. The inlet throat flow distribution was uniform and the Mach number and pressure level were of the correct magnitude for efficient combustor design. The utilization of a swept compression field to meet the starting requirements of a fixed-geometry inlet produced neither flow instability nor a tendency to unstart.

Torrence, M. G.↗
NASA NTRS1975

Nonreactive mixing study of a scramjet swept-strut fuel injector

The results are presented of a cold-mixing investigation performed to supply combustor design information and to determine optimum normal fuel-injector configurations for a general scramjet swept-strut fuel injector. The experimental investigation was made with two swept struts in a closed duct at a Mach number of 4.4 and a nominal ratio of jet mass flow to air mass flow of 0.0295, with helium used to simulate hydrogen fuel. Four injector patterns were evaluated; they represented the range of hole spacing and the ratio of jet dynamic pressure to free-stream dynamic pressure. Helium concentration, pitot pressure, and static pressure in the downstream mixing region were measured to generate the contour plots needed to define the mixing-region flow field and the mixing parameters. Experimental results show that the fuel penetration from the struts was less than the predicted values based on flat-plate data; but the mixing rate was faster and produced a mixing length less than one-half that predicted.

Mcclinton, C. R.↗
NASA NTRS1975

Viscous/potential flow about multi-element two-dimensional and infinite-span swept wings: Theory and experiment

The viscous subsonic flow past two-dimensional and infinite-span swept multi-component airfoils is studied theoretically and experimentally. The computerized analysis is based on iteratively coupled boundary layer and potential flow analysis. The method, which is restricted to flows with only slight separation, gives surface pressure distribution, chordwise and spanwise boundary layer characteristics, lift, drag, and pitching moment for airfoil configurations with up to four elements. Merging confluent boundary layers are treated. Theoretical predictions are compared with an exact theoretical potential flow solution and with experimental measures made in the Ames 40- by 80-Foot Wind Tunnel for both two-dimensional and infinite-span swept wing configurations. Section lift characteristics are accurately predicted for zero and moderate sweep angles where flow separation effects are negligible.

Olson, L. E.↗
NASA NTRS1976

Viscous/potential flow about multi-element two-dimensional and infinite-span swept wings - Theory and experiment

The viscous subsonic flow past two-dimensional and infinite-span swept multi-component airfoils is studied theoretically and experimentally. The computerized analysis is based on iteratively coupled boundary-layer and potential-flow analysis. The method, which is restricted to flows with only slight separation, gives surface pressure distribution, chordwise and spanwise boundary-layer characteristics, lift, drag, and pitching moment for airfoil configurations with up to four elements. Merging confluent boundary layers are treated. Theoretical predictions are compared with an exact theoretical potential flow solution and with experimental measures made in the Ames 40- by 80-Foot Wind Tunnel for both two-dimensional and infinite-span swept wing configurations. Section lift characteristics are accurately predicted for zero and moderate sweep angles where flow separation effects are negligible.

Olson, L. E.↗
NASA NTRS1977

Downstream influence of swept slot injection in hypersonic turbulent flow

Results of an experimental and numerical investigation of tangential swept slot injection into a thick turbulent boundary layer at Mach 6 are presented. Film cooling effectiveness, skin friction, and flow structure downstream of the swept slot injection were investigated. The data were compared with that for unswept slots, and it was found that cooling effectiveness and skin friction reductions are not significantly affected by sweeping the slot.

Hefner, J. N.↗
NASA NTRS1977

Aerodynamic characteristics of a small-scale straight and swept-back wing with knee-blown jet flaps

Two sting-mounted, 50.8 cm (20 in.) span, knee-blown, jet-flap models were tested in a large (2.1- by 2.5-m (7- by 10-ft) subsonic wind tunnel. A straight- and swept-wing model were tested with fixed flap deflection with various combinations of full-span leading-edge slats. The swept-wing model was also tested with wing tip extensions. Data were taken at angles-of-attack between 0 deg and 40 deg, at dynamic pressures between 143.6 N/sq m (3 lb/sq ft) and 239.4 N/sq m (5 lb/sq ft), and at Reynolds numbers (based on wing chord) ranging from 100,000 to 132,000. Jet flap momentum blowing coefficients up to 10 were used. Lift, drag, and pitching-moment coefficients, and exit flow profiles for the flap blowing are presented in graphical form without analysis.

Morehouse, G. G.↗
NASA NTRS1978

Aerodynamic characteristics of a hypersonic research airplane concept having a 70 deg swept double-delta wing at Mach number 0.2

A wind-tunnel of the static longitudinal, lateral and directional stability characteristics of a hypersonic research airplane concept having a 70 deg swept double-delta wing was conducted in the Langley low-turbulence pressure tunnel. The configuration variables included wing planform, tip fins, center fin, and scramjet engine modules. A mach number of 0.2 was investigated over a Reynolds number (based on fuselage length) range of 2,200,000 to 19.75 x 1,000,000 (with a majority of tests at 10.0 x 1,000,000. Tests were conducted through an angle-of-attack range from about -2 deg to 34 deg at angles of sideslip of 0 deg to 5 deg, and at elevon deflection of 0 deg, -5 deg, -10 deg, -15 deg, and -20 deg. The drag coefficient of the integrated scramjet engine appears relatively constant with Reynolds number at the test Mach number of 0.2. Mild pitch-up was exhibited by the models equipped with tip fins. The forward delta, a highly swept forward portion of the wing, was destabilizing. The center fin model has a higher trimmed maximum lift-drag ratio and a wider trim lift and angle-of-attack range than the tip fin model. Both the tip fin models and center fin models exhibited positive dihedral effect and positive directional stability. Roll control was positive for the tip fin model, but yaw due to roll control was unfavorable.

Penland, J. A.↗
NASA NTRS1979

The effect of canard relative size and vertical location on the subsonic longitudinal and lateral-directional static aerodynamic characteristics for a model with a swept forward wing

A general research fighter model was tested in the Langley 7- by 10-foot high speed tunnel at a Mach number of 0.3. The model was tested with a 32 deg swept forward wing mounted in mid-, low-, and high-wing positions. For the mid-wing configuration, the model was tested with a 51.7 deg swept back canard mounted in mid-, low-, and high-canard positions. For the mid-wing mid-canard and the mid-wing high-canard configurations, canards of similar planform having two different areas were tested. The angle-of-attack range was from approximately -4 deg to 48 deg at sideslip angles of 0 deg, -5 deg, and 5 deg.

Huffman, J. K.↗
NASA NTRS1978

Characterization of a swept-strut hydrogen fuel-injector for scramjet applications

Results of an experimental investigation of a swept-strut hydrogen fuel-injector simulating the center strut of a three strut scramjet module at Mach 6 flight conditions are presented. Detailed wall pressure distributions from over 100 separate tests with overall fuel flow from 0.1 to 1.3 times stoichiometric and test gas stagnation temperature from 1100 to 2400 K were recorded. The distance for pressure rise from the point of injection was found to increase with increasing test stagnation temperature. This trend indicates that chemical kinetics in the immediate region of perpendicular injection are not likely to be the mechanism controlling the onset of pressure rise. A fluid dynamic mechanism is suggested involving separation of the boundary layer downstream of injection which is forced upstream from the trailing edge by pressure rise due to combustion occurring in the base region of the strut. The results obtained indicate that the swept-strut fuel-injector concept can be adapted to a wide range of flight conditions by varying the amount of perpendicular fuel injection.

Northam, G. B.↗
NASA NTRS1980

Exploratory investigation of the effects of vortex bursting on the high angle-of-attack lateral-directional stability characteristics of highly-swept wings

A recent low-speed wind-tunnel investigation of highly-swept wings has shown that vortex breakdown at high angles of attack can cause large destabilizing effects on static lateral-directional stability characteristics, and that the destabilizing effects of vortex breakdown can be greatly aggravated by model support strut interference effects. The present paper discusses these effects based on the results of static force tests of several highly-swept wing configurations for different wind-tunnel strut setup arrangements. Also included in the paper are photographs obtained during tuft-, smoke-, and helium-bubble flow visualization studies to indicate wing flow behavior patterns

Johnson, J. L., Jr.↗
NASA NTRS1980

Dynamic response of a forward-swept-wing model at angles of attack up to 15 deg at a Mach number of 0.8

Root mean square (rms) bending moments for a dynamically scaled, aeroelastic wing of a proposed forward swept wing, flight demonstrator airplane are presented for angles of attack up to 15 deg at a Mach number of 0.8 The 0.6 size semispan model had a leading edge forward sweep of 44 deg and was constructed of composite material. In addition to broad band responses, individual rms responses and total damping ratios are presented for the first two natural modes. The results show that the rms response increases with angle of attack and has a peak value at an angle of attack near 13 deg. In general, the response was characteristic of buffeting and similar to results often observed for aft swept wings. At an angle of attack near 13 deg, however, the response had characteristics associated with approaching a dynamic instability, although no instability was observed over the range of parameters investigated.

Doggett, R. V., Jr.↗
NASA NTRS1980

Flameholding characteristics of a swept-strut H2 fuel-injector for scramjet applications

A series of direct-connect tests are conducted which simulate the flow around the center swept-strut fuel-injector of a scramjet engine module. The experimental geometry includes both perpendicular and parallel fuel injectors which are swept with respect to the upstream flow direction in a manner simulating the flow geometry in the combustion region of the scramjet module. Seven different strut injector geometries are evaluated for their performance, flameholding, and inlet-combustor interaction characteristics. The most efficient combustion process is exhibited by the configuration having the deepest step with perpendicular injector orifices located 3.5 to 4.5 step heights downstream from the step. However, long centerbody and staged injection configurations perform as equally well as the deep step configuration when evaluating only the amount of perpendicular fuel injection. Since the staged injection configuration exhibits the lowest ignition and flameholding limit, it is suggested that the optimum injection configuration should incorporate a deep step with staged injection in order to improve the low temperature autoignition-flameholding characteristics.

Northam, G. B.↗