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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Low-Disturbance Flow Characteristics of the NASA-Ames Laminar Flow Supersonic Wind Tunnel

A unique, low-disturbance (quiet) supersonic wind tunnel has been commissioned at the NASA-Ames Fluid Mechanics Laboratory (FML) to support Supersonic Laminar Flow Control (SLFC) research. Known as the Laminar Flow Supersonic Wind Tunnel (LFSWT), this tunnel is designed to operate at potential cruise Mach numbers and unit Reynolds numbers (Re) of the High Speed Civil Transport (HSCT). The need to better understand the receptivity of the transition phenomena on swept (HSCT) wings to attachment-line contamination and cross-flows has provided the impetus for building the LFSWT. Low-disturbance or "quiet" wind tunnels are known to be an essential part of any meaningful boundary layer transition research. In particular, the receptivity of supersonic boundary layers to wind tunnel disturbances can significantly alter the transition phenomena under investigation on a test model. Consequently, considerable effort has gone into the design of the LFSWT to provide quiet flow. The paper describes efforts to quantify the low-disturbance flows in the LFSWT operating at Mach 1.6, as a precursor to transition research on wing models. The research includes: (1) Flow measurements in both the test section and settling chamber of the LFSWT, using a full range of measurement techniques; (2) Study of the state of the test section boundary layer so far by using a single hot-wire mounted above the floor centerline, with and without boundary layer trips fitted at the test section entrance; (3) The effect of flow quality of unsteady supersonic diffuser flow, joint steps and gaps, and wall vibration.

Wolf, Stephen W. D.↗
NASA NTRS1921

On a new type of wind tunnel

Discussed here is a new type of wind tunnel, its advantages, the difficulties attendant upon its use, and the special methods required for its operation. The main difference between the new type of wind tunnel and the ones now in operation is the use of a different fluid. The idea is to diminish the effect of viscosity If air is compressed, it becomes a fluid with new properties - a fluid that is best suited for reliable and exact tests on models. When air is compressed, its density increases, but its viscosity does not. It is argued that the increase of pressure greatly increases the range and value of wind tunnel tests. Reynolds number, deductions from the Reynolds law, the causes of errors that result in differences between tests on models and actual flights, and the dimensions of a compressed air wind tunnel are covered.

Munk, Max↗
NASA NTRS1974

Static and control investigations of an 0.030-scale space shuttle orbiter configuration 140A/B model in the Ames Research Center 11 by 11-foot transonic wind tunnel (OA53A), Volume 1

A wind tunnel test of an 0.030 scale model of the Rockwell International Configuration 140A/B Space Shuttle Vehicle Orbiter were conducted in the Ames Research Center 11- by 11-Foot Transonic Wind Tunnel. This part (part A) of test series 0A53 was conducted at Mach numbers of 0.6, 0.8, 0.9, 1.05, and 1.20, and at Reynolds numbers from 1.8 x to 6.5 million per foot. The objective of this test was to establish and verify longitudinal and lateral-directional aerodynamic performance, stability, and control characteristics for the Configuration 140A/B SSV Orbiter. Reynolds number studies were performed for certain nominal control-settings. An alternate leading-edge wing configuration and sealed elevon-split arrangement were tested. Bodyflap, elevon, speedbrake, and rudder hinge moments were measured in addition to standard six-component forces and moments and base pressure data. Furthermore, six-component force and moment data were measured for the vertical tail assembly.

Nichols, M. E.↗
NASA NTRS1972

Low-speed aerodynamic characteristics of a 17-percent-thick supercritical airfoil section, including a comparison between wind-tunnel and flight data

Wind-tunnel tests were conducted to determine the low speed two dimensional aerodynamic characteristics of a 17-percent-thick supercritical airfoil. The results were compared with three dimensional wind-tunnel and flight data. The tests were conducted over a Mach number range from 0.15 to 0.30. Reynolds numbers based on the airfoil chord varied from 2.0x10 to the 6th power to 15.0x10 to the 6th power.

Robert J McGhee↗
NASA NTRS1995

Documentation and archiving of the Space Shuttle wind tunnel test data base. Volume 1: Background and description

Development of the space shuttle necessitated an extensive wind tunnel test program, with the cooperation of all the major wind tunnels in the United States. The result was approximately 100,000 hours of space shuttle wind tunnel testing conducted for aerodynamics, heat transfer, and structural dynamics. The test results were converted into Chrysler DATAMAN computer program format to facilitate use by analysts, a very cost effective method of collecting the wind tunnel test results from many test facilities into one centralized location. This report provides final documentation of the space shuttle wind tunnel program. The two-volume set covers evolution of space shuttle aerodynamic configurations and gives wind tunnel test data, titles of wind tunnel data reports, sample data sets, and instructions for accessing the digital data base.

Romere, Paul O.↗
NASA NTRS1974

A forward speed effects study on jet noise from several suppressor nozzles in the NASA/Ames 40- by 80-foot wind tunnel

A test program was conducted in a 40 by 80 foot wind tunnel to evaluate the effect of relative velocity on the jet noise signature of a conical ejector, auxiliary inlet ejector, 32 spokes and 104 tube nozzle with and without an acoustically treated shroud. The freestream velocities in the wind tunnel were varied from 0 to 103.6 m/sec (300 ft/sec) for exhaust jet velocities of 259.1 m/sec (850 ft/sec) to 609.6 m/sec (2000 ft/sec). Reverberation corrections for the wind tunnel were developed and the procedure is explained. In conjunction with wind tunnel testing the nozzles were also evaluated on an outdoor test stand. The wind tunnel microphone arrays were duplicated during the outdoor testing. The data were then extrapolated for comparisons with data measured using a microphone array placed on a 30.5 meter (100 ft) arc. Using these data as a basis, farfield to nearfield arguments are presented with regards to the data measured in the wind tunnel. Finally, comparisons are presented between predictions made using existing methods and the measured data.

Beulke, M. R.↗
NASA NTRS1985

A new 3D LDV system for the NASA Ames 6 x 6 ft. wind tunnel

An obvious extension of wind tunnel laser Doppler velocimetry (LDV), which is currently mainly limited to two-component measurements, would involve the measurement of three simultaneous velocity components. The present paper is concerned with an approach to reduce the degree of optical complexity involved in the design of a three-dimensional (3D) LDV system, taking into account the use of polarization separation. Such a system, utilizing polarization as well as color separation, has been designed and tested in a 6 x 6 foot supersonic wind tunnel. The considered instrument was designed for the on line measurement of three mean velocity components, turbulence levels, and shear stresses on a number of models under a wide variety of test conditions. Attention is given to optical details, data reduction, and sample application.

Owen, F. K.↗
NASA NTRS1988

Large-scale Advanced Prop-fan (LAP) high speed wind tunnel test report

High Speed Wind Tunnel testing of the SR-7L Large Scale Advanced Prop-Fan (LAP) is reported. The LAP is a 2.74 meter (9.0 ft) diameter, 8-bladed tractor type rated for 4475 KW (6000 SHP) at 1698 rpm. It was designated and built by Hamilton Standard under contract to the NASA Lewis Research Center. The LAP employs thin swept blades to provide efficient propulsion at flight speeds up to Mach .85. Testing was conducted in the ONERA S1-MA Atmospheric Wind Tunnel in Modane, France. The test objectives were to confirm that the LAP is free from high speed classical flutter, determine the structural and aerodynamic response to angular inflow, measure blade surface pressures (static and dynamic) and evaluate the aerodynamic performance at various blade angles, rotational speeds and Mach numbers. The measured structural and aerodynamic performance of the LAP correlated well with analytical predictions thereby providing confidence in the computer prediction codes used for the design. There were no signs of classical flutter throughout all phases of the test up to and including the 0.84 maximum Mach number achieved. Steady and unsteady blade surface pressures were successfully measured for a wide range of Mach numbers, inflow angles, rotational speeds and blade angles. No barriers were discovered that would prevent proceeding with the PTA (Prop-Fan Test Assessment) Flight Test Program scheduled for early 1987.

Campbell, William A.↗
NASA NTRS1983

A common geometric data-base approach for computer-aided manufacturing of wind-tunnel models and theoretical aerodynamic analysis

A more automated process to produce wind tunnel models using existing facilities is discussed. A process was sought to more rapidly determine the aerodynamic characteristics of advanced aircraft configurations. Such aerodynamic characteristics are determined from theoretical analyses and wind tunnel tests of the configurations. Computers are used to perform the theoretical analyses, and a computer aided manufacturing system is used to fabricate the wind tunnel models. In the past a separate set of input data describing the aircraft geometry had to be generated for each process. This process establishes a common data base by enabling the computer aided manufacturing system to use, via a software interface, the geometric input data generated for the theoretical analysis. Thus, only one set of geometric data needs to be generated. Tests reveal that the process can reduce by several weeks the time needed to produce a wind tunnel model component. In addition, this process increases the similarity of the wind tunnel model to the mathematical model used by the theoretical aerodynamic analysis programs. Specifically, the wind tunnel model can be machined to within 0.008 in. of the original mathematical model. However, the software interface is highly complex and cumbersome to operate, making it unsuitable for routine use. The procurement of an independent computer aided design/computer aided manufacturing system with the capability to support both the theoretical analysis and the manufacturing tasks was recommended.

See, M. J.↗
NASA NTRS2011

Thermal and Pressure Characterization of a Wind Tunnel Force Balance Using the Single Vector System

Wind tunnel research at NASA Langley Research Center s 31-inch Mach 10 hypersonic facility utilized a 5-component force balance, which provided a pressurized flow-thru capability to the test article. The goal of the research was to determine the interaction effects between the free-stream flow and the exit flow from the reaction control system on the Mars Science Laboratory aeroshell during planetary entry. In the wind tunnel, the balance was exposed to aerodynamic forces and moments, steady-state and transient thermal gradients, and various internal balance cavity pressures. Historically, these effects on force measurement accuracy have not been fully characterized due to limitations in the calibration apparatus. A statistically designed experiment was developed to adequately characterize the behavior of the balance over the expected wind tunnel operating ranges (forces/moments, temperatures, and pressures). The experimental design was based on a Taylor-series expansion in the seven factors for the mathematical models. Model inversion was required to calculate the aerodynamic forces and moments as a function of the strain-gage readings. Details regarding transducer on-board compensation techniques, experimental design development, mathematical modeling, and wind tunnel data reduction are included in this paper.

Lynn, Keith C.↗
NASA NTRS1985

A survey of cryogenic wind tunnels

Following the development of the cryogenic wind tunnel at the NASA Langley Research Center in 1972, a large number of cryogenic wind-tunnel projects have been undertaken at various research establishments around the world. The purpose of this paper is to describe some of the more significant of these projects. Described in this paper are cryogenic wind-tunnel projects in China (CARDC), England (College of Aeronautics at Cranfield, RAE-Bedford, and University of Southampton), 'Europe' (Pilot European Transonic Windtunnel at NAL-Amsterdam, and the European Transonic Windtunnel proposed for DFVLR-Koeln), France (ONERA-CERT), Germany (DFVLR-Koeln, and DFVLR-Goettingen), Japan (NAL, University of Tsukuba, and National Defense Academy), Sweden (Rollab), and the United States (Douglas Aircraft Co., University of Illinois at Urbana-Champaign, and NASA-Langley).

Kilgore, R. A.↗
NASA NTRS1985

Investigation of Low-temperature Solders for Cryogenic Wind Tunnel Models

The advent of high Reynolds number cryogenic wind tunnels has forced alteration of manufacturing and assembly techniques and eliminated usage of many materials associated with conventional wind tunnel models. One of the techniques affected is soldering. Solder alloys commonly used for wind tunnel models are susceptible to low-temperature embrittlement and phase transformation. The low-temperature performance of several solder alloys is being examined during research and development activities being conducted in support of design and fabrication of cryogenic wind tunnel models. Among the properties examined during these tests are shear strength, surface quality, joint stability, and durability when subjected to dynamic loading. Results of these tests and experiences with recent models are summarized.

Firth, G. C.↗
NASA NTRS2021

NASA Ames Research Center Unitary Plan Wind Tunnel Fall 2018 Outage - Motor 1 Activity: Stator Shift

The Unitary Plan Wind Tunnel consists of the 11 x 11- Foot Transonic Wind Tunnel and the 9 x 7 foot Supersonic Wind Tunnel. The four 65,000hp electric motors that drive the wind tunnel compressors require periodic maintenance. In order to inspect the motors without the removal of drive shaft components, the stator must be shifted away from the motor. This process is referred to as "Stator Shift". Video is mp4 formatted with runtime of 2 mins 54 secs.

Wind Tunnel↗
NASA NTRS2000

Modernization and Activation of the NASA Ames 11- by 11-Foot Transonic Wind Tunnel

The Unitary Plan Wind Tunnel (UPWT) was modernized to improve performance, capability, productivity, and reliability. Automation systems were installed in all three UPWT tunnel legs and the Auxiliaries facility. Major improvements were made to the four control rooms, model support systems, main drive motors, and main drive speed control. Pressure vessel repairs and refurbishment to the electrical distribution system were also completed. Significant changes were made to improve test section flow quality in the 11-by 11-Foot Transonic leg. After the completion of the construction phase of the project, acceptance and checkout testing was performed to demonstrate the capabilities of the modernized facility. A pneumatic test of the tunnel circuit was performed to verify the structural integrity of the pressure vessel before wind-on operations. Test section turbulence, flow angularity, and acoustic parameters were measured throughout the tunnel envelope to determine the effects of the tunnel flow quality improvements. The new control system processes were thoroughly checked during wind-off and wind-on operations. Manual subsystem modes and automated supervisory modes of tunnel operation were validated. The aerodynamic and structural performance of both the new composite compressor rotor blades and the old aluminum rotor blades was measured. The entire subsonic and supersonic envelope of the 11-by 11-Foot Transonic leg was defined up to the maximum total pressure.

Kmak, Frank J.↗
NASA NTRS1998

Drive System Enhancement in the NASA Lewis Research Center Supersonic Wind Tunnels

An overview of NASA Lewis' Aeropropulsion Wind Tunnel Productivity Improvements was presented at the 19th AIAA Advanced Measurement & Ground Testing Technology Conference. Since that time Lewis has implemented subsonic operation in their 10- by 10-Foot Supersonic Wind Tunnel as had been proven viable in the 8- by 6 and 9- by 15-Foot Wind Tunnel Complex and discussed at the aforementioned conference. In addition, two more years of data have been gathered to help quantify the true productivity increases in these facilities attributable to the drive system and operational improvements. This paper was invited for presentation at the 20th Advanced Measurement and Ground Testing Conference to discuss and quantify the productivity improvements in the 10- by 10 SWT since the implementation of less than full complement motor operation. An update on the increased productivity at the 8- by 6 and 9- by 15-Foot facility due to drive system enhancements will also be presented.

Becks, Edward A.↗
NASA NTRSDate not supplied

In Pursuit of CFD-based Wind Tunnel Calibrations

Computational fluid dynamic simulations of models tested in wind tunnels require a high level of fidelity and accuracy, particularly for the purposes of CFD validation efforts. Considerable effort is required to ensure a sufficient characterization of both the physical geometry of the wind tunnel, the thermodynamics of the tunnel, and flow conditions in the test section. The condition setting process among subsonic wind tunnels, closed or open throat, is generally the same, though they can differ in specific details of the thermodynamics. The derivation, application, and error estimation of condition setting and calibration is discussed. Computational flow solutions of the high-speed leg of the NASA Langley Research Center 14- by 22-Foot Subsonic Tunnel are used to evaluate the calibration process and discuss calibration curve sensitivities. Duplicating the characteristics of a particular wind tunnel is difficult at best. A calibration curve derived from the computational method is the most consistent method to use for tunnel condition setting.

wind tunnel↗
NASA NTRS1990

Cryogenic wind tunnels

Some of the major problems in wind tunnel research and testing are reviewed and solutions are suggested. Support interference, wall interference, flow unsteadiness, and low Reynolds number are all discussed. The evolution of cryogenic wind tunnels, principles of operation, and testing capabilities are reviewed. Several test facilities are described and the use of cryogenic wind tunnels to increase test Reynolds number is suggested.

Kilgore, Robert A.↗
NASA NTRS1997

System Dynamic Analysis of a Wind Tunnel Model with Applications to Improve Aerodynamic Data Quality

The research investigates the effect of wind tunnel model system dynamics on measured aerodynamic data. During wind tunnel tests designed to obtain lift and drag data, the required aerodynamic measurements are the steady-state balance forces and moments, pressures, and model attitude. However, the wind tunnel model system can be subjected to unsteady aerodynamic and inertial loads which result in oscillatory translations and angular rotations. The steady-state force balance and inertial model attitude measurements are obtained by filtering and averaging data taken during conditions of high model vibrations. The main goals of this research are to characterize the effects of model system dynamics on the measured steady-state aerodynamic data and develop a correction technique to compensate for dynamically induced errors. Equations of motion are formulated for the dynamic response of the model system subjected to arbitrary aerodynamic and inertial inputs. The resulting modal model is examined to study the effects of the model system dynamic response on the aerodynamic data. In particular, the equations of motion are used to describe the effect of dynamics on the inertial model attitude, or angle of attack, measurement system that is used routinely at the NASA Langley Research Center and other wind tunnel facilities throughout the world. This activity was prompted by the inertial model attitude sensor response observed during high levels of model vibration while testing in the National Transonic Facility at the NASA Langley Research Center. The inertial attitude sensor cannot distinguish between the gravitational acceleration and centrifugal accelerations associated with wind tunnel model system vibration, which results in a model attitude measurement bias error. Bias errors over an order of magnitude greater than the required device accuracy were found in the inertial model attitude measurements during dynamic testing of two model systems. Based on a theoretical modal approach, a method using measured vibration amplitudes and measured or calculated modal characteristics of the model system is developed to correct for dynamic bias errors in the model attitude measurements. The correction method is verified through dynamic response tests on two model systems and actual wind tunnel test data.

Buehrle, Ralph David↗