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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Measuring Wall Interference Correction Accuracy: An Overview of the NTF Program (Invited)

An off-line version of the Transonic Wall Interference Correction System (TWICS) has been implemented for the NASA Langley National Transonic Facility (NTF). The correction capability includes both solid and horizontally slotted test section configurations. A study is underway to assess and characterize the accuracy of the TWICS code as implemented in the NTF. The purpose of this paper is to present the test program and display preliminary results.

Walker, Eric L.↗
NASA NTRS2008

Comparison of NTF Experimental Data with CFD Predictions from the Third AIAA CFD Drag Prediction Workshop

Recently acquired experimental data for the DLR-F6 wing-body transonic transport con figuration from the National Transonic Facility (NTF) are compared with the database of computational fluid dynamics (CFD) predictions generated for the Third AIAA CFD Drag Prediction Workshop (DPW-III). The NTF data were collected after the DPW-III, which was conducted with blind test cases. These data include both absolute drag levels and increments associated with this wing-body geometry. The baseline DLR-F6 wing-body geometry is also augmented with a side-of-body fairing which eliminates the flow separation in this juncture region. A comparison between computed and experimentally observed sizes of the side-of-body flow-separation bubble is included. The CFD results for the drag polars and separation bubble sizes are computed on grids which represent current engineering best practices for drag predictions. In addition to these data, a more rigorous attempt to predict absolute drag at the design point is provided. Here, a series of three grid densities are utilized to establish an asymptotic trend of computed drag with respect to grid convergence. This trend is then extrapolated to estimate a grid-converged absolute drag level.

Vassberg, John C.↗
NASA NTRSDate not supplied

NASA 5.2%-Scale High Lift Common Research Model (CRM-HL) Test in the National Transonic Facility (NTF)

Problem: Predicting CL,max and assessing transition, turbulence models, and Reynolds number effect predictions in CFD requires wind tunnel data for comparison. Objective: Expand the CFD validation database by running multiple models designed using the same reference geometry in various wind tunnels around the world. The wind tunnel data and model geometry will be open source to allow for CFD validation use. Approach: Run the NASA 5.2%-scale High Lift Common Research Model (CRM-HL) semi-span model at the National Transonic Facility (NTF). Test the model at chord Reynolds numbers (Rec) between 1.6 million and 30 million and at varying Q/Es to assess Reynolds number effects and aeroelasticity affects on the model, while collecting force and moment, pressure and wing deformation data. Test the model with ice shapes installed on the leading edges. Results: Ran eight model configurations, including four landing, two landing with ice shapes installed, and two takeoff configurations. Ran in air (120°F) and nitrogen operations (-50°F, -180°F and -250°F) at 7 different chord Reynolds numbers. The data compare well with previous tests of the same model at DLR (The Germany Aerospace Center) and the 14- by 22-Foot Subsonic Tunnel (14x22). Significance: Provided valuable high Reynolds number data on a high lift configuration to the worldwide research community. Provide icing data at flight Reynolds number to the research community.

CRM-HL↗
NASA NTRS1981

The NTF as a national facility

The future evolution of the NTF as a national facility was discussed. The aerodynamic test facility is charged with maintaining the test data and operating the facility with maximum productivity to increase the utility as well as to minimize the test costs. Efforts are under way to increase productivity of the wind tunnels. The future developments needed include: (1) the elimination of wall interference uncertainties; (2) the elimination of minimization of sting interference; and (3) the achievement of free air quality low turbulence airflow. Research in the wall interference area, smart walls, is reported.

Brown, C. E.↗
NASA NTRS1983

NTF user operations requirements

A procedure to be followed for a model to be accepted for testing in the NTF is outlined. Planning meeting; pre-test conference; model receipts, assembly, and checkout; and model installation and test are discussed.

Fuller, D. E.↗
NASA NTRS1984

Design study of test models of maneuvering aircraft configurations for the National Transonic Facility (NTF)

The feasibility of designing advanced technology, highly maneuverable, fighter aircraft models to achieve full scale Reynolds number in the National Transonic Facility (NTF) is examined. Each of the selected configurations are tested for aeroelastic effects through the use of force and pressure data. A review of materials and material processes is also included.

Griffin, S. A.↗
NASA NTRS1985

A theoretical study of non-adiabatic surface effects for a model in the NTF cryogenic wind tunnel

A theoretical analysis was made of the severity and effect of nonadiabatic surface conditions for a model in the NTF cryogenic wind tunnel. The nonadiabatic condition arises from heaters that are used to maintain a constant thermal environment for instrumentation internal to the model. The analysis was made for several axi-symmetric representations of a fuselage cavity, using a finite element heat conduction code. Potential flow and boundary layer codes were used to calculate the convection condition for the exterior surface of the model. The results of the steady state analysis show that it is possible to maintain the surface temperature very near the adiabatic value, with the judicious use of insulating material. Even for the most severe nonadiabatic condition studied, the effects on skin friction drag and displacement thickness were only marginally significant. The thermal analysis also provided an estimate of the power required to maintain a specified cavity temperature.

Macha, J. M.↗
NASA NTRS1985

NTF: Soldering Technology Development for Cryogenics

The advent of the National Transonic Facility (NTF) brought about a new application for an old joining method, soldering. Soldering for use at cryogenic temperatures requires that solders remain ductile and free from tin-pest (grey tin), have toughness to withstand aerodynamic loads associated with flight research, and maintain their surface finishes. Solders are used to attach 347 Stainless-Steel tubing in surface grooves of models. The solder must fill up the gap and metallurgically bound to the tubing and model. Cryogenic temperatures require that only specific materials for models can be used, including: Vasco Max 200 CVM, lescalloy A-286 Vac Arc, pH 13-8 Mo. Solders identified for testing at this time are: 50% Sn - 49.5% Pb - 0.5% Sb, 95% Sn - 5% Sb, 50% In 50% Pb, and 37.5% Sn - 37.5% Pb - 25% In. With these materials and solders, it is necessary to determine their solderability. After solderability is determined, tube/groove specimens are fabricated and stressed under cryogenic temperatures. Compatible solders are then used for acutual models.

Hall, E. T., Jr.↗
NASA NTRS1988

Heating requirements and nonadiabatic surface effects for a model in the NTF cryogenic wind tunnel

A theoretical study has been made of the severity of nonadiabatic surface conditions arising from internal heat sources within a model in a cryogenic wind tunnel. Local surface heating is recognized as having an effect on the development of the boundary layer, which can introduce changes in the flow about the model and affect the wind tunnel data. The geometry was based on the NTF Pathfinder I wind tunnel model. A finite element heat transfer computer code was developed and used to compute the steady state temperature distribution within the body of the model, from which the surface temperature distribution was extracted. Particular three dimensional characteristics of the model were represented with various axisymmetric approximations of the geometry. This analysis identified regions on the surface of the model susceptible to surface heating and the magnitude of the respective surface temperatures. It was found that severe surface heating may occur in particular instances, but could be alleviated with adequate insulating material. The heat flux through the surface of the model was integrated to determine the net heat required to maintain the instrumentation cavity at the prescribed temperature. The influence of the nonadiabatic condition on boundary layer properties and on the validity of the wind tunnel simulation was also investigated.

Macha, J. M.↗
NASA NTRS1988

Design of high-Reynolds-number flat-plate experiments in the NTF

The design of an experiment to measure skin friction and turbulent boundary layer characteristics at Reynolds numbers exceeding 1 x 10 to the 9th is described. The experiment will be conducted in a zero-pressure-gradient flow on a flat plate in the National Transonic Facility (NTF). The development of computational codes to analyze the aerodynamic loads and the blockage is documented. Novel instrumentation techniques and models, designed to operate in cryogenic environments, are presented. Special problems associated with aerodynamic loads, surface finish, and hot-wire anemometers are discussed.

Saric, William S.↗
NASA NTRS1989

The US National Transonic Facility, NTF

The construction of the National Transonic Facility was completed in September 1982 and the start-up and checkout of tunnel systems were performed over the next two years. In August 1984, the Operational Readiness Review (ORR) was conducted and the facility was declared operational for final checkout of cryogenic instrumentation and control systems, and for the aerodynamic calibration and testing to commence. Also, the model access system for the cryogenic mode of operation would be placed into operation along with tunnel testing. Since the ORR, a host of operating problems resulting from the cryogenic environment were identified and solved. These range from making mechanical and electrical systems functional to eliminating temperature induced model vibration to coping with the outgassing of moisture from the thermal insulation. Additionally, a series of aerodynamic tests have demonstrated data quality and provided research data on several configurations. Some of the more significant efforts are reviewed since the ORR and the NTF status concerning hardware, instrumentation and process controls systems, operating constraints imposed by the cryogenic environment, and data quality are summarized.

Bruce, Walter E., Jr.↗
NASA NTRS1989

Cryogenic balances for the US NTF

Force balances were used to obtain aerodynamic data in the National Transonic Facility (NTF) wind tunnel since it became operational in 1983. These balances were designed, fabricated, gaged, and calibrated to Langley Research Center's specifications to operate over the temperature range of -320 F to +140 F without thermal control. Some of the materials and procedures developed to obtain a balance that would perform in this environment are reviewed. The degree of success in using these balances thus far is reported. Some of the problem areas that need additional work are specified and some of the progress addressing these problems is described.

Ferris, Alice T.↗
NASA NTRS1992

User guide for WIACX: A transonic wind-tunnel wall interference assessment and correction procedure for the NTF

A three dimensional transonic Wind-tunnel Interference Assessment and Correction (WIAC) procedure developed specifically for use in the National Transonic Facility (NTF) at NASA Langley Research Center is discussed. This report is a user manual for the codes comprising the correction procedure. It also includes listings of sample procedures and input files for running a sample case and plotting the results.

Garriz, Javier A.↗
NASA NTRS1991

On the measurement of subsonic flow around an appended body of revolution at cryogenic conditions in the NTF

Fluid mechanics scaling is briefly reviewed and testing ship models at high Reynolds numbers in the National Transonic Facility is discussed. Particular attention is given to the 1986 body of revolution experiment, the expanded model capabilities for a future body of revolution experiment, major features of a future flat plate experiment, the proposed liquid helium tunnel from the user's point of view, and a comparison of the NTF and the Conceptual Helium Tunnel.

Coder, David W.↗
NASA NTRS1993

Computation of transonic viscous flow past the NTF 65-degree Delta Wing

This project is a continuation of the work performed in the summers of 1991 and 1992, during which a 9-block structured grid for the computational domain around each of the four NTF 65-degree Delta Wing models with the sting mount were created. The objective of the project is to validate and supplement the test data on the wing models by computing the viscous flow field about the models.

Wu, Chivey↗
NASA NTRS2004

Wall Interference Study of the NTF Slotted Tunnel Using Bodies of Revolution Wall Signature Data

This paper is a description of the analysis of blockage corrections for bodies of revolution for the slotted-wall configuration of the National Transonic Facility (NTF) at the NASA Langley Research Center (LaRC). A wall correction method based on the measured wall signature is used. Test data from three different-sized blockage bodies and four wall ventilation settings were analyzed at various Mach numbers and unit Reynolds numbers. The results indicate that with the proper selection of the boundary condition parameters, the wall correction method can predict blockage corrections consistent with the wall measurements for Mach numbers as high as 0.95.

Iyer, Venkit↗
NASA NTRS2004

Wall Interference Study of the NTF Slotted Tunnel Using Bodies of Revolution Wall Signature Data

This paper is a description of the analysis of blockage corrections for bodies of revolution for the slotted-wall configuration of the National Transonic Facility (NTF) at the NASA Langley Research Center (LaRC). A wall correction method based on the measured wall signature is used. Test data from three different-sized blockage bodies and four wall ventilation settings were analyzed at various Mach numbers and unit Reynolds numbers. The results indicate that with the proper selection of the boundary condition parameters, the wall correction method can predict blockage corrections consistent with the wall measurements for Mach numbers as high as 0.95.

Iyer, Venkit↗