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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 163 records · Page 9

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NASA NTRS1992

Further investigations of the aeroelastic behavior of the AFW wind-tunnel model using transonic small disturbance theory

The Computational Aeroelasticity Program-Transonic Small Disturbance (CAP-TSD) code, developed at LaRC, is applied to the active flexible wing wind-tunnel model for prediction of transonic aeroelastic behavior. A semi-span computational model is used for evaluation of symmetric motions, and a full-span model is used for evaluation of antisymmetric motions, and a full-span model is used for evaluation of antisymmetric motions. Static aeroelastic solutions using CAP-TSD are computed. Dynamic deformations are presented as flutter boundaries in terms of Mach number and dynamic pressure. Flutter boundaries that take into account modal refinements, vorticity and entropy corrections, antisymmetric motion, and sensitivity to the modeling of the wing tip ballast stores are also presented with experimental flutter results.

Silva, Walter A.↗

NASA NTRS2005

An Evaluation of Measured Pressure Signatures From Wind-Tunnel Models of Three Low-Boom Concepts

Revised 1990-1991 sonic-boom design and analysis methodology was assessed by applying it to the design of three low-boom concepts. Models of these concepts were built and used to measure pressure signatures in the wind tunnel. An analysis of wind-tunnel data showed unexpected nacelle-inlet and the nacelle-wing interference-lift shocks in the pressure signatures from the two engine-under-the-wing models, but not in the measured pressure signatures from the wind-tunnel model with the engine nacelles mounted on the aft fuselage. However, additional lift-induced shocks were found in the pressure signature data from all three wind-tunnel models indicating that other flow-field disturbance effects were present.

Mack, Robert J.↗

NASA NTRS1982

A proposed configuration for a stepped specimen to be used in the systematic evaluation of factors influencing warpage in metallic alloys being used for cryogenic wind tunnel models

A proposed configuration for a stepped specimen to be used in the system evaluation of mechanisms that can introduce warpage or dimensional changes in metallic alloys used for cryogenic wind tunnel models is described. Considerations for selecting a standard specimen are presented along with results obtained from an investigation carried out for VASCOMAX 200 maraging steel. Details of the machining and measurement techniques utilized in the investigation are presented. Initial results from the sample of VASCOMAX 200 show that the configuration and measuring techniques are capable of giving quantitative results.

Wigley, D. A.↗

NASA NTRS1991

Investigation of the aeroelastic stability of the AFW wind-tunnel model using CAP-TSD

The Computational Aeroelasticity Program - Transonic Small Disturbance (CAP-TSD) code, developed at the NASA Langley Research Center, is applied to the Active Flexible Wing (AFW) wind tunnel model for prediction of the model's transonic aeroelastic behavior. A semi-span computational model is used for evaluation of symmetric motions and a full span model is used for evaluation of antisymmetric motions. Static aeroelastic solutions using CAP-TSD are computed. Dynamic (flutter) analyses are then performed as perturbations about the static aeroelastic deformations and presented as flutter boundaries in terms of Mach number and dynamic pressure. Flutter boundaries that take into account modal refinements, vorticity and entropy corrections, antisymmetric motions and sensitivity to the modeling of the wing tip ballast stores are also presented and compared with experimental flutter results.

Silva, Walter A.↗

NASA NTRS1972

Effect of transient winds on the flow quality of an open-circuit wind-tunnel model

The effect of a transient wind on the test-section flow quality of an open-circuit wind tunnel was investigated experimentally. The investigation was restricted to transient wind effects associated with the inlet. A small open-circuit wind tunnel was placed outside in the real wind environment. Test-section speed and angularity as well as wind speed and direction was measured by high-response instrumentation. The inlet configuration was varied with a set of screens, a removable honeycomb, and a removable inlet lip. Acceptable flow was obtained at all wind angles and for wind- to test-section-velocity ratios up to 0.4 with an inlet configuration having five screens, a honeycomb, and a lip. With inlet configurations sensitive to winds, a transient wind parallel to the tunnel axis produced local fluctuations in test-section speed and angularity; however, oscillation of the average test-section speed was not evident. The effect of wind direction was negligible up to wind angles of 45 deg relative to the tunnel axis. At larger wind angles, flow distortions occurred primarily on the windward side of the test section.

Breunlin, D. C.↗

NASA NTRS1979

Performance characteristics of a wedge nozzle installed on an F-18 propulsion wind tunnel model

The results of two-dimensional wedge non-axisymmetric nozzle (2D-AIN) tests to determine its performance relative to the baseline axisymmetric nozzle using an F-18 jet effects wind tunnel model are presented. Configurations and test conditions simulated forward thrust-minus drag, thrust vectoring/induced lift, and thrust reversing flight conditions from Mach .6 to 1.20 and attack angles up to 10 degrees. Results of the model test program indicate that non-axisymmetric nozzles can be installed on a twin engine fighter aircraft model with equivalent thrust minus drag performance as the baseline axisymmetric nozzles. Thrust vectoring capability of the non-axisymmetric nozzles provided significant jet-induced lift on the nozzle/aftbody and horizontal tail surfaces. Thrust reversing panels deployed from the 2D-AIN centerbody wedge were very effective for static and inflight operation

Petit, J. E.↗

NASA NTRS1992

Further investigations of the aeroelastic behavior of the AFW wind-tunnel model using transonic small disturbance theory

The CAP-TSD (Computational Aeroelasticity Program - Transonic Small Disturbance) code, developed at the NASA Langley Research Center, is applied to the Active Flexible Wing wind-tunnel model for prediction of transonic aeroelastic behavior. A semi-span computational model is used for evaluation of symmetric motions, and a full-span model is used for evaluation of antisymmetric motions. Static aeroelastic solutions using CAP-TSD are computed. Dynamic (flutter) analyses then are performed as perturbations about the static aeroelastic deformations and presented as flutter boundaries in terms of Mach number and dynamic pressure. Flutter boundaries that take into account modal refinements, vorticity and entropy corrections, antisymmetric motions and sensitivity to the modeling of the wing tip ballast stores also are presented and compared with experimental flutter results.

Silva, Walter A.↗

NASA NTRS2016

Wind Tunnel Model Design for Sonic Boom Studies of Nozzle Jet with Shock Interactions

NASA and Industry are performing vehicle studies of configurations with low sonic boom pressure signatures. The computational analyses of modern configuration designs have matured to the point where there is confidence in the prediction of the pressure signature from the front of the vehicle, but uncertainty in the aft signatures with often greater boundary layer effects and nozzle jet pressures. Wind tunnel testing at significantly lower Reynolds numbers than in flight and without inlet and nozzle jet pressures make it difficult to accurately assess the computational solutions of flight vehicles. A wind tunnel test in the NASA Ames 9- by 7-Foot Supersonic Wind Tunnel from Mach 1.6 to 2.0 will be used to assess the effects of shocks from components passing through nozzle jet plumes on the sonic boom pressure signature and provide datasets for comparison with CFD codes. A large number of high-fidelity numerical simulations of wind tunnel test models with a variety of shock generators that simulate horizontal tails and aft decks have been studied to provide suitable models for sonic boom pressure measurements using a minimally intrusive pressure rail in the wind tunnel. The computational results are presented and the evolution of candidate wind tunnel models is summarized and discussed in this paper.

Wind↗

NASA NTRS1991

High angle of attack control law development for a free-flight wind tunnel model using direct eigenstructure assignment

Flight-control laws are developed for a wind-tunnel aircraft model flying at a high angle of attack by using a synthesis technique called direct eigenstructure assignment. The method employs flight guidelines and control-power constraints to develop the control laws, and gain schedules and nonlinear feedback compensation provide a framework for considering the nonlinear nature of the attack angle. Linear and nonlinear evaluations show that the control laws are effective, a conclusion that is further confirmed by a scale model used for free-flight testing.

Wendel, Thomas R.↗

NASA NTRS1993

Structural dynamic testing of composite propfan blades for a cruise missile wind tunnel model

The Naval Weapons Center at China Lake, California is currently evaluating a counter rotating propfan system as a means of propulsion for the next generation of cruise missiles. The details and results of a structural dynamic test program are presented for scale model graphite-epoxy composite propfan blades. These blades are intended for use on a cruise missile wind tunnel model. Both dynamic characteristics and strain operating limits of the blades are presented. Complications associated with high strain level fatigue testing methods are also discussed.

Elgin, Stephen D.↗

NASA NTRSDate not supplied

NASA 5.2%-Scale Semispan High Lift Common Research Model Wind Tunnel Test at the 14- by 22-Foot Subsonic Tunnel

A wind tunnel test of the NASA 5.2%-scale Semispan High Lift Common Research Model (CRM-HL) was conducted at the 14- by 22-Foot Subsonic Tunnel (14x22) in the fall of 2022. The main purpose of the test was a model checkout before shipping it overseas. The model was shipped to Germany in the spring of 2023, and the team wanted to be sure that instrumentation in the model was working, all of the model parts fit together well, and model changes could be done smoothly, as designed while installed in a wind tunnel. Force and moment and pressure data were collected during the test, and while these data were a secondary objective, they can be used for for tunnel-to-tunnel verification of the model, and for database supplementation for the NASA CRM-HL ecosystem. The test was run from August 15, 2022 through September 8, 2022. Eight configurations were tested at Mach 0.2 and 0.26, over an alpha range from -4deg to +24deg. All of the configurations that were tested accomplished testing of all model parts. This test campaign was a unique opportunity to test a complicated model design in a wind tunnel that is less expensive to test in and has easier model access than the tunnel that it was designed to run in. The test was invaluable in providing lessons learned about building up and running the model, and the model was returned to the model manufacturer from December 2022 to February 2023 for updates to make model changes easier, to make design fixes on the model, and to do clean up work on the model.

Semispan↗

NASA NTRS1959

The Effect of Lower Surface Spoilers on the Transonic Trim Change of a Wind-Tunnel Model of a Fighter Airplane Having a Modified Delta Wing

In an attempt to find an aerodynamic means of counteracting the transonic trim change of a fighter airplane, lower surface spoilers were tested on a 0.055-scale wind-tunnel model. The Mach number range of the tests was 0.8 to 1.2 at Reynolds numbers of approximately 4 million. Although the spoilers produced a moderate decrease in the trim change at low altitudes, they also produced a large increase in drag. Pressure-distribution tests with external fuel tanks showed large pressure changes on the lower surface of the wing due to the tanks.

Robinson, Robert C.↗

NASA NTRS1976

A device for rapid determination of thermophysical properties of phase-change wind-tunnel models

An experimental method for direct measurement of the thermophysical properties of wind tunnel heat transfer models was developed. The technique consists of placing the model under a bank of high intensity, radiant heaters so that the fast opening water cooled shutters, which isolate the heater bank from the model, allow a step-input heat rate to be applied. Measurements of the heat transfer rate coupled with a surface-temperature time history of the same material are sufficient to determine the material thermophysical properties. An infrared thermometer is used to measure model surface temperature and a slug calorimeter provides heat transfer rate information. The output from the infrared thermometer and calorimeter is then fed into an analog-to-digital converter which provides digitized data to a computer. This computer then calculates combined thermophysical properties and a teleprinter prints out all the data. Thus, results are available within 7 minutes of test initiation as opposed to the weeks or months required using prior techniques.

Creel, T. R., Jr.↗

NASA NTRS1979

Supercritical tests of a self-optimizing, variable-Camber wind tunnel model

A testing procedure was used in a 16-foot Transonic Propulsion Wind Tunnel which leads to optimum wing airfoil sections without stopping the tunnel for model changes. Being experimental, the optimum shapes obtained incorporate various three-dimensional and nonlinear viscous and transonic effects not included in analytical optimization methods. The method is a closed-loop, computer-controlled, interactive procedure and employs a Self-Optimizing Flexible Technology wing semispan model that conformally adapts the airfoil section at two spanwise control stations to maximize or minimize various prescribed merit functions subject to both equality and inequality constraints. The model, which employed twelve independent hydraulic actuator systems and flexible skins, was also used for conventional testing. Although six of seven optimizations attempted were at least partially convergent, further improvements in model skin smoothness and hydraulic reliability are required to make the technique fully operational.

Levinsky, E. S.↗

NASA NTRS1988

Space shuttle phase B wind tunnel model and test information. Volume 2: Orbiter configuration

Archived wind tunnel test data are available for flyback booster or other alternative recoverable configurations as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle. Considerable wind tunnel data was acquired by the competing contractors and the NASA centers for an extensive variety of configurations with an array of wing and body planforms. All contractor and NASA wind tunnel test data acquired in the Phase B development have been compiled into a data base and are available for applying to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Data Base is structured by vehicle component and configuration type. Basic components include the booster, the orbiter, and the launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retro-glide and twin body. Orbiter configuration types include straight and delta wings, lifting body, drop tanks, and double delta wings. Launch configuration types include booster and orbiter components in various stacked and tandem combinations.

Glynn, J. L.↗

NASA NTRS1988

Space shuttle phase B wind tunnel model and test information. Volume 2: Orbiter configuration

Archived wind tunnel test data are available for flyback booster or other alternate recoverable configurations as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle. Considerable wind tunnel data was acquired by the competing contractors and the NASA centers for an extensive variety of configurations with an array of wing and body planforms. All contractor and NASA wind tunnel test data acquiredin the Phase B development have been compiled into a database and are available for applying to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Database is structured by vehicle component and configuration type. Basic components include the booster, the orbiter, and the launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retroglide, and twin body. Orbiter configuration types include straight and delta wings, lifting body, drop tanks, and double delta wings. Launch configration types include booster and orbiter components in various stacked and tandom combinations. The digital database consists of 220 files of data containing basic tunnel recorded data.

Glynn, J. L.↗

NASA NTRS1988

Space shuttle phase B wind tunnel model and test information. Volume 3: Launch configuration

Archived wind tunnel data are available for flyback booster or other alternative recoverable configurations as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle. Considerable wind tunnel data was acquired by the competing contractors and the NASA Centers for an extensive variety of configurations with an array of wing and body planforms. All contractor and NASA wind tunnel data acquired in the Phase B development have been compiled into a data base and are available for application to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Database is structured by vehicle component and configuration type. Basic components include booster, orbiter and launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retroglide and twin body. Orbital configuration types include straight and delta wings, lifting body, drop tanks and double delta wings. This is Volume 3 (Part 2) of the report -- Launch Configuration -- which includes booster and orbiter components in various stacked and tandem combinations.

Glynn, J. L.↗

NASA NTRS1988

Space shuttle phase B wind tunnel model and test information. Volume 1: Booster configuration

Archived wind tunnel test data are available for flyback booster or other alternative recoverable configurations as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle. Considerable wind tunnel data was acquired by the competing contractors and the NASA Centers for an extensive variety of configurations with an array of wing and body planforms. All contractor and NASA wind tunnel test data acquired in the Phase B development have been compiled into a database and are available for application to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Database is structured by vehicle component and configuration type. Basic components include the booster, the orbiter and the launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retroglide and twin body. Orbiter configuration types include straight and delta wings, lifting body, drop tanks, and double delta wings. Launch configurations include booster and orbiter components in various stacked and tandem combinations. This is Volume 1 (Part 1) of the report -- Booster Configuration.

Glynn, J. L.↗