Wind-Tunnel Flutter Tests at Mach Numbers up to 3.0 of Boeing Wing Models for Weapons System 110A
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Levey, G. M.↗
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Results for “wind tunnel testing”
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Aerodynamic results of wind tunnel separation tests on a 0.01-scale model (32-OTS) space shuttle integrated vehicle in the AEDC-VKF-SWTA (IA57)
The integrated space shuttle vehicle was tested to determine proximity force and moment data for the orbiter/external tank and solid rocket booster (SRB) with and without separation rockets firing for both single and dual booster runs. Data were obtained at points t = 0 sec, t = 1.25 sec, and t = 2 sec on the nominal SRB separation trajectory.
Daileda, J. J.↗
Decomposition of nitric oxide in a hot nitrogen stream to synthesize air for hypersonic wind tunnel combustion testing
A clean source of high enthalpy air was obtained from the exothermic decomposition of nitric oxide in the presence of strongly heated nitrogen. A nitric oxide jet was introduced into a confined coaxial nitrogen stream. Measurements were made of the extent of mixing and reaction. Experimental results are compared with one- and two-dimensional chemical kinetics computations. Both analyses predict much lower reactivity than was observed experimentally. Inlet nitrogen temperatures above 2400 K were sufficient to produce experimentally a completely reacted gas stream of synthetic air.
Zumdieck, J. F.↗
Reynolds number criticality in dynamic tests
To extrapolate from subscale wind tunnel tests to full-scale flight is a well-recognized problem. It becomes especially critical for present day high performance missiles and aircraft which operate at high angles of attack where separated flow effects often dominate the vehicle aerodynamics. The dynamic effects of flow separation can usually not be simulated at subscale Reynolds numbers. This is illustrated by examples of tests with slender vehicles and high performance aircraft. It is shown how analytic means can be developed establishing theoretical relationships between dynamic and static aerodynamic characteristics and how such means make it possible to extrapolate analytically from subscale tests to full-scale flight. The roll of future high Reynolds number facilities in establishing such 'analytic extrapolation' tools is discussed.
Ericsson, L. E.↗
Evaluation of the Acoustic Measurement Capability of the NASA Langley V/STOL Wind Tunnel Open Test Section with Acoustically Absorbent Ceiling and Floor Treatments
The single source location used for helicopter model studies was utilized in a study to determine the distances and directions upstream of the model accurate at which measurements of the direct acoustic field could be obtained. The method used was to measure the decrease of sound pressure levels with distance from a noise source and thereby determine the Hall radius as a function of frequency and direction. Test arrangements and procedures are described. Graphs show the normalized sound pressure level versus distance curves for the glass fiber floor treatment and for the foam floor treatment.
Theobald, M. A.↗
In-flight transition measurement on a 10 deg cone at Mach numbers from 0.5 to 2.0
Boundary layer transition measurements were made in flight on a 10 deg transition cone tested previously in 23 wind tunnels. The cone was mounted on the nose of an F-15 aircraft and flown at Mach numbers room 0.5 to 2.0 and altitudes from 1500 meters (5000 feet) to 15,000 meters (50,000 feet), overlapping the Mach number/Reynolds number envelope of the wind tunnel tests. Transition was detected using a traversing pitot probe in contact with the surface. Data were obtained near zero cone incidence and adiabatic wall temperature. Transition Reynolds number was found to be a function of Mach number and of the ratio of wall temperature to adiabatic all temperature. Microphones mounted flush with the cone surface measured free-stream disturbances imposed on the laminar boundary layer and identified Tollmien-Schlichting waves as the probable cause of transition. Transition Reynolds number also correlated with the disturbance levels as measured by the cone surface microphones under a laminar boundary layer as well as the free-stream impact.
Fisher, D. F.↗
Wind-tunnel preflight test program for aeroassist flight experiment
A proposed Aeroassist Flight Experiment (AFE) will simulate return from geosynchronous orbit to low-earth orbit to provide fundamental information about the hypersonic flow conditions surrounding aeroassisted orbital transfer vehicles (AOTV's). Future AOTV design must rely heavily on computational fluid dynamic (CFD) computer codes now under development, since the entry conditions are beyond the simulation capabilities of ground-based test facilities. However, existing codes and best available ground-based test facilities must provide for design of the AFE. The AFE ground-based test program provides data for calibration of existing and developing pertinent CFD codes. Confidence in code prediction capability increases with ability to predict forces and moments, pressure and heat-transfer distributions, shock shapes, and surface streamline directions. The ground-based test program provides these data over a wide range of hypersonic test parameters. This paper describes the test program, models, facilities, and some representative results.
Wells, William L.↗
The RSRA/X-Wing experiment - A status report
This paper reports on the current status of the NASA/Army Rotor Systems Research Aircraft (RSRA)/X-Wing Experiment program designed to demonstrate the technology readiness of the X-Wing concept for a prototype vehicle. Program accomplishments, test results on all of the necessary major hardware elements, and the results of flight tests are described. Future wind tunnel testing of the full-scale rotor system in the NASA NF SAC facility is presently being planned; these tests must be completed before an objective assessment can be made regarding the viability of the RSRA/X-Wing concept for an operational aircraft.
Lane, James W.↗
The application of cryogenics to high Reynolds number testing in wind tunnels. II - Development and application of the cryogenic wind tunnel concept
The development and application of the cryogenic wind tunnel concept at the Langley Research Center are described. Particular attention is given to the low-speed cryogenic tunnel and the pilot transonic cryogenic tunnel. The major conclusions with respect to the operation and performance of the pilot transonic cryogenic tunnel after almost 4000 h of operation at cryogenic temperatures are that: (1) purging, cooldown, and warm-up times are acceptable and can be predicted with good accuracy, and that (2) the quantity of liquid nitrogen required for cooldown and running can be predicted with good accuracy. The U.S. National Transonic Facility is described in detail.
Kilgore, R. A.↗
Experimental validation study of an analytical model of discrete frequency sound propagation in closed-test-section wind tunnels
The principal objective is to assess the adequacy of linear acoustic theory with an impedence wall boundary condition to model the detailed sound field of an acoustic source in a duct. Measurements and calculations are compared of a simple acoustic source in a rectangular concrete duct lined with foam on the walls and anechoic end terminations. Measurement of acoustic pressure for twelve wave numbers provides variation in frequency and absorption characteristics of the duct walls. Close to the source, where the interference of wall reflections is minimal, correlation is very good. Away from the source, correlation degrades, especially for the lower frequencies. Sensitivity studies show little effect on the predicted results for changes in impedance boundary condition values, source location, measurement location, temperature, and source model for variations spanning the expected measurement error.
Mosher, Marianne↗
Evaluation of discrete frequency sound in closed-test-section wind tunnels
The principal objective of this study is to assess the adequacy of linear acoustic theory with an impedance wall boundary condition for modeling the detailed sound field of an acoustic source in a duct. This study compares measurements and calculations of a simple acoustic source in a rectangular concrete duct lined with foam on the walls and anechoic end terminations. Measuring acoustic pressure for 12 wave numbers provides variation in frequency and absorption characteristics of the duct walls. The cases in this study contain low frequencies and low wall absorptions corresponding to measurements of low-frequency helicopter noise in a lined wind tunnel. This regime is particularly difficult to measure in wind tunnels due to high levels of the reverberant field relatively close to the source. Close to the source, where the interference of wall reflections is minimal, correlation is very good. Away from the source, correlation degrades, especially for the lower frequencies. Sensitivity studies show little effect on the predicted results for changes in impedance boundary condition values, source location, measurement location, temperature, and source model for variations spanning the expected measurement error.
Mosher, Marianne↗
Analytical study of wind-tunnel acoustic testing of propellers
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Eversman, Walter↗
Evaluation of discrete frequency sound in closed-test-section wind tunnels
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Mosher, Marianne↗
Wind tunnel force tests in wing systems through large angles of attack
Force tests on a systematic series of wing systems over a range of angle of attack from minus forty-five degrees to plus ninety degrees are covered in this report. The investigation was made on monoplane and biplane wing models to determine the effects of variations of tip shape, aspect ratio, flap setting, stagger, gap, decalage, sweepback, and airfoil profile.
Wenzinger, Carl J↗
Free-flight-tunnel investigation of dynamic longitudinal stability as influenced by the static stability measured in wind-tunnel force tests under conditions of constant thrust and constant power
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STABILITY, LONGITUDINAL - STATIC↗
Construction of Models for Tests in Wind Tunnels
Report deals with the methods of constructing aerofoils and all other parts of a model airplane, including discussion of the degree of accuracy.
Norton, F H↗
Tests of Five Full-Scale Propellers in the Presence of a Radial and a Liquid-Cooled Engine Nacelle, Including Tests of Two Spinners
Wind-tunnel tests are reported of five 3-blade 10-foot propellers operating in front of a radial and a liquid-cooled engine nacelle. The range of blade angles investigated extended from 15 degrees to 45 degrees. Two spinners were tested in conjunction with the liquid-cooled engine nacelle. Comparisons are made between propellers having different blade-shank shapes, blades of different thickness, and different airfoil sections. The results show that propellers operating in front of the liquid-cooled engine nacelle had higher take-off efficiencies than when operating in front of the radial engine nacelle; the peak efficiency was higher only when spinners were employed. One spinner increased the propulsive efficiency of the liquid-cooled unit 6 percent for the highest blade-angle setting investigated and less for lower blade angles. The propeller having airfoil sections extending into the hub was superior to one having round blade shanks. The thick propeller having a Clark y section had a higher take-off efficiency than the thinner one, but its maximum efficiency was possibly lower. Of the three blade sections tested, Clark y, R.A.F. 6, and NACA 2400-34, the Clark y was superior for the high-speed condition, but the R.A.F. 6 excelled for the take-off condition.
Biermann, David↗
An experimental investigation of a Mach 3.0 high-speed civil transport at supersonic speeds
An experimental study was conducted to determine the aerodynamic characteristics of a proposed high speed civil transport. This configuration was designed to cruise at Mach 3.0 and sized to carry 250 passengers for 6500 n.mi. The configuration consists of a highly blended wing body and features a blunt parabolic nose planform, a highly swept inboard wing panel, a moderately swept outboard wing panel, and a curved wingtip. Wind tunnel tests were conducted in the Langley Unitary Plan Wind Tunnel on a 0.0098-scale model. Force, moment, and pressure data were obtained for Mach numbers ranging from 1.6 to 3.6 and at angles of attack ranging from -4 to 10 deg. Extensive flow visualization studies (vapor screen and oil flow) were obtained in the experimental program. Both linear and advanced computational fluid dynamics (CFD) theoretical comparisons are shown to assess the ability to predict forces, moments, and pressures on configurations of this type. In addition, an extrapolation of the wind tunnel data, based on empirical principles, to full-scale conditions is compared with the theoretical aerodynamic predictions.
Hernandez, Gloria↗