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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 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Effects of wing/elevon gap sealing flapper doors on orbiter elevon effectiveness of model 16-0 in the NAAL 7.75 by 11 foot continuous flow wind tunnel (OA119A)

Space shuttle orbiter elevon effectiveness was measured with the 6 inch elevon/elevon and elevon/fuselage gaps and various configurations of wing/elevon upper hingeline gap sealing flapper doors. The elevon configuration parametric variations consisted of sealing the lower hingeline to prevent flow-through and testing a long chord flapper door, a short chord flapper door, no flapper door (elevon/wing gap upper hingeline completely open), and a completely sealed elevon at elevon deflections from +20 deg to -40 deg. Preliminary data analysis indicates loss of elevon effectiveness at deflections more negative than -20 deg, and little or no effect of flapper door configuration on elevon effectiveness. Flow visualization photographs taken at alpha = 15 deg for two flapper door configurations substantiated the force data results. Aerodynamic force and moment data were measured in the body axis by a 2.5 inch task type internal strain gage balance. The model was sting supported through the base region with a nominal angle of attack range of -10 deg less than or equal to alpha less than or equal to 24 deg at a model angle of sideslip of Beta equal to 0 deg.

Mennell, R.↗
NASA NTRS1974

Aerodynamic drag reduction tests on a full-scale tractor-trailer combination with several add-on devices

Aerodynamic drag tests were performed on a conventional cab-over-engine tractor with a 45-foot trailer and five commercially available or potentially available add-on devices using the coast-down method. The tests ranged in velocity from approximately 30 miles per hour to 65 miles per hour and included some flow visualization. A smooth, level runway at Edwards Air Force Base was used for the tests, and deceleration measurements were taken with both accelerometers and stopwatches. An evaluation of the drag reduction results obtained with each of the five add-on devices is presented.

Montoya, L. C.↗
NASA NTRS1974

Development of a Fowler flap system for a high performance general aviation airfoil

A two-dimensional wind-tunnel evaluation of two Fowler flap configurations on the new GA(W)-1 airfoil was conducted. One configuration used a computer-designed 29-percent chord Fowler flap. The second configuration was modified to have increased Fowler action with a 30-percent chord flap. Force, pressure, and flow-visualization data were obtained at Reynolds numbers of 2.2 million to 2.9 million. Optimum slot geometry and performance were found to be close to computer predictions. A C sub L max of 3.8 was achieved. Optimum flap deflection, slot gap, and flap overlap are presented as functions of C sub L. Tests were made with the lower surface cusp filled in to show the performance penalties that result. Some data on the effects of adding vortex generators and hinged-plate spoilers were obtained.

Wentz, W. H., Jr.↗
NASA NTRS1975

Wind tunnel tests of an 0.019-scale space shuttle integrated vehicle -2A configuration (model 14-OTS) in the NASA Ames 8 by 7 foot unitary wind tunnel (IA12C), volume 1

The purpose of the test was to determine the effects of cold jet gas plumes on (1) the integrated vehicle longitudinal and lateral-directional force data, (2) exposed wing hinge moment, (3) wing pressure distributions, (4) orbiter MPS external pressure distributions, and (5) model base pressure. The similarity between solid and gaseous plumes was investigated, and fluorescent oil flow visualization studies were conducted.

Hardin, R. B.↗
NASA NTRS1975

Wind tunnel tests of an 0.019-scale space shuttle integrated vehicle -2A configuration (model 14-OTS) in the NASA Ames 8 X 7 foot unitary wind tunnel, volume 2

The purpose of the test was to determine the effects of cold jet gas plumes on (1) the integrated vehicle longitudinal and lateral-directional force data, (2) exposed wing hinge moment, (3) wing pressure distributions, (4) orbiter MPS external pressure distributions, and (5) model base pressures. An investigation was undertaken to determine the similarity between solid and gaseous plumes; fluorescent oil flow visualization studies were also conducted. Plotted wing pressure data is tabulated.

Hardin, R. B.↗
NASA NTRS1975

Wind tunnel tests of an 0.019-scale space shuttle integrated vehicle -2A configuration (model 14-OTS) in the NASA Ames 8 X 7 foot unitary wind tunnel, volume 3

Tests were conducted to determine the effects of cold jet gas plumes on (1) the integrated vehicle longitudinal and lateral-directional force data, (2) exposed wing hinge moment, (3) wing pressure distributions, (4) orbiter MPS external pressure distributions, and (5) model base pressures. An investigation was undertaken to determine the similarity between solid and gaseous plumes; fluorescent oil flow visualization studies were also conducted. Tabulated data listings are included.

Hardin, R. B.↗
NASA NTRS1975

Experimental study of the effect on span loading on aircraft wakes

Measurements were made in the NASA-Ames 40- by 80-foot wind tunnel of the rolling moment induced on a following model in the wake 13.6 spans behind a subsonic transport model for a variety of trailing edge flap settings of the generator. It was found that the rolling moment on the following model was reduced substantially, compared to the conventional landing configuration, by reshaping the span loading on the generating model to approximate a span loading, found in earlier studies, which resulted in reduced wake velocities. This was accomplished by retracting the outboard trailing edge flaps. It was concluded, based on flow visualization conducted in the wind tunnel as well as in a water tow facility, that this flap arrangement redistributes the vorticity shed by the wing along the span to form three vortex pairs that interact to disperse the wake.

Corsiglia, V. R.↗
NASA NTRS1974

The development of experimental techniques for the study of helicopter rotor noise

The features of existing wind tunnels involved in noise studies are discussed. The acoustic characteristics of the MIT low noise open jet wind tunnel are obtained by employing calibration techniques: one technique is to measure the decay of sound pressure with distance in the far field; the other technique is to utilize a speaker, which was calibrated, as a sound source. The sound pressure level versus frequency was obtained in the wind tunnel chamber and compared with the corresponding calibrated values. Fiberglas board-block units were installed on the chamber interior. The free field was increased significantly after this treatment and the chamber cut-off frequency was reduced to 160 Hz from the original designed 250 Hz. The flow field characteristics of the rotor-tunnel configuration were studied by using flow visualization techniques. The influence of open-jet shear layer on the sound transmission was studied by using an Aeolian tone as the sound source. A dynamometer system was designed to measure the steady and low harmonics of the rotor thrust. A theoretical Mach number scaling formula was developed to scale the rotational noise and blade slap noise data of model rotors to full scale helicopter rotors.

Widnall, S. E.↗
NASA NTRS1975

Vortex shedding from a blunt trailing edge with equal and unequal external mean velocities

A flow visualization study showed that strong Karman vortices are developed behind the blunt trailing edge of a plate when the free stream velocities over both surfaces are equal. These vortices tend to disappear when the surface velocities are unequal. This observation provided an explanation for the occurrence and disappearance of the lip noise often present in coaxial jets. Vortex formation and lip noise occurred at a Strouhal number of about 0.2 based on the lip thickness and the average of the external steady-state velocities. Results from theoretical calculations of the vortex formation, based on an inviscid, incompressible analysis of the motion of point vortices, were in good agreement with the experimental observations.

Brinich, P. F.↗
NASA NTRS1975

The effect of wing dihedral and section suction distribution on vortex bursting

Eleven semi-span wing models were tested in the 1/8-scale model of the Langley V/STOL tunnel to qualitatively study vortex bursting. Flow visualization was achieved by using helium filled soap bubbles introduced upstream of the model. The angle of attack range was from 0 deg to 45 deg. The results show that the vortex is unstable, that is, the bursting point location is not fixed at a given angle of attack but moves within certain bounds. Upstream of the trailing edge, the bursting point location has a range of two inches; downstream, the range is about six inches. Anhedral and dihedral appear to have an insignificant effect on the vortex and its bursting point location. Altering the section suction distribution by improving the triangularity generally increases the angle of attack at which vortex bursting occurs at the trailing edge.

Washburn, K. E.↗
NASA NTRS1975

The development of experimental techniques for the study of helicopter rotor noise

The acoustic characteristics of a low noise open jet wind tunnel have been obtained by employing two different calibration techniques. One technique is to measure the decay of sound pressure with distance in far field. The other technique is to utilize a calibrated speaker as a sound source. The sound pressure level vs frequency was obtained in the wind tunnel testing chamber and compared with the corresponding calibrated values. The results of two different techniques agree with each other. Fiberglass board-block units were installed on the testing chamber interior. The free field was increased significantly after this treatment and the testing chamber cut-off frequency was reduced to 160 Hz from the original designed 250 Hz. The flow field characteristics of the rotor-tunnel configuration were studied by using flow visualization techniques.

Harris, W. L.↗
NASA NTRS1975

Experimental study of the effect of span loading on aircraft wakes

Measurements were made in the NASA-Ames 40- by 80-Foot Wind Tunnel of the rolling moment induced on a following model in the wake 13.6 spans behind a subsonic transport model for a variety of trailing edge flap settings of the generator. It was found that the rolling moment on the following model was reduced substantially, compared to the conventional landing configuration, by reshaping the span loading on the generating model to approximate a span loading, found in earlier studies, which resulted in reduced wake velocities. This was accomplished by retracting the outboard trailing edge flaps. It was concluded, based on flow visualization conducted in the wind tunnel as well as in a water tow facility, that this flap arrangement redistributes the vorticity shed by the wing along the span to form three vortex pairs that interact to disperse the wake.

Corsiglia, V. R.↗
NASA NTRS1975

Wing Tip Vortex Drag

Optimization of L/D through minimizing induced drag through a detailed flow study together with force, pressure and vorticity measurements is considered. Flow visualization with neutral helium bubbles provides an excellent means of observing the effects of configuration changes.

Muirhead, V. U.↗
NASA NTRS1975

Design and preliminary tests of a blade tip air mass injection system for vortex modification and possible noise reduction on a full-scale helicopter rotor

Full-scale tests were conducted on the Langley helicopter rotor test facility as part of a study to evaluate the effectiveness of a turbulent blade tip air mass injection system in alleviating the impulsive noise (blade slap) caused by blade-vortex interaction. Although blade-slap conditions could not be induced during these tests, qualitative results from flow visualization studies using smoke showed that the differential velocity between the jet velocity and the rotor tip speed was a primary parameter controlling the vortex modification.

Pegg, R. J.↗
NASA NTRS1975

An investigation in MSFC 14-inch TWT to determine the static stability characteristics of 0.004-scale model (74-OTS) space shuttle vehicle 5 configuration (IA33), volume 1

Wind tunnel tests were conducted to: (1) determine the static stability characteristics of the Shuttle Vehicle 5 configuration; (2) determine the effect on the Vehicle 5 aerodynamic characteristics of External Tank (ET) and Solid Rocket Booster (SRB) nose shape, SRB nozzle shroud flare angle, orbiter to tank fairing, and sting location; (3) provide flow visualization using thin film oil paint; and (4) determine rudder, body flap, and inboard and outboard elevon hinge moments. The mated vehicle model was mounted in three different ways: (1) the orbiter mounted on the balance with the SRB's attached to the tank and the tank in turn attached to the orbiter; (2) the tank mounted on the balance (with the sting protruding through the tank base) with the SRB's and orbiter attached to the tank, and (3) with the tank mounted on the balance and the balance in turn supported by a forked sting entering the nozzle of each SRB, extending forward into the SRB's then crossing over to the tank to provide a balance socket. Data were obtained for Mach numbers from 0.6 through 4.96 at angles-of-attack and -sideslip from -10 to 10 degrees.

Allen, E. C.↗
NASA NTRS1975

Intrepretation of surface features and surface processes on Mars

Eolian erosion and deposition on earth was studied in order to interpret the eolian land forms of Mars. Emphasis of the wind tunnel studies was on the flow field around models of eolian forms. Areas of the wind tunnel studies include: simulation of the atmospheric boundary layer; velocity profile measurements around different models in the desert boundary layer, and estimating shear stress distributions on the model surfaces; flow visualization techniques; streamline mapping using tuft photographs; and roughness contrasts.

Gad-El-hak, M.↗
NASA NTRS1975

Heat-flux gage measurements on a flat plate at a Mach number of 4.6 in the VSD high speed wind tunnel, a feasibility test (LA28)

The feasibility of employing thin-film heat-flux gages was studied as a method of defining boundary layer characteristics at supersonic speeds in a high speed blowdown wind tunnel. Flow visualization techniques (using oil) were employed. Tabulated data (computer printouts), a test facility description, and photographs of test equipment are given.

Source record↗
NASA NTRS1975

An investigation of the 0.0091 scale External Tank ogive nose (MSFC model 470) in the MSFC 14 inch TWT to determine the pressure distribution around the External Tank Nose (TA3F), volume 1

The model tested was a 0.0091 scale representation of the ogive nose section of the External Tank with nose cap and lightning rod and protuberances. Pressure distribution around the nose cap was determined. Pressure data were also obtained along the ogive nose. Data were obtained over an angle of attack range of + or -5 degrees and over a Mach number range of .6 to 4.96. The Reynolds number per unit length (ft.) ranged from 4.1 million to 4.96 million. There were 22 pressure ports in a single row. Circumferential positions of 0, 22.5, 45, 67.5 and 90 degrees were simulated by rotating the model. The LO2 feed line and LO2 recirculation line were simulated. The effects of the nose spike were investigated over a range of Mach numbers. The data will be useful for venting analyses. Photographs showing flow visualization of the test configuration are given.

Ramsey, P. E.↗