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Sample records for acoustic wind tunnel

  1. Fiber-optic interferometric acoustic sensors for wind tunnel applications

    NASA Technical Reports Server (NTRS)

    Cho, Y. C.

    1993-01-01

    Progress in developing fiber-optic interferometric sensors for aeroacoustic measurements in wind tunnels, performed under the NASA program, is reported. Preliminary results show that the fiber-optic interferometer sensor array is a powerful instrument for solving complex acoustic measurement problems in wind tunnels, which cannot be resolved with the conventional transducer technique.

  2. Acoustic measurement study 40 by 80 foot subsonic wind tunnel

    NASA Technical Reports Server (NTRS)

    1974-01-01

    An acoustical study conducted during the period from September 1, 1973 to April 30, 1974 measured sound pressure levels and vibration amplitudes inside and outside of the subsonic tunnel and on the tunnel structure. A discussion of the technical aspects of the study, the field measurement and data reduction procedures, and results are presentd, and conclusions resulting from the study which bear upon near field and far field tunnel noise, upon the tunnel as an acoustical enclosure, and upon the sources of noise within the tunnel drive system are given.

  3. Acoustic Survey of a 3/8-Scale Automotive Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Booth, Earl R., Jr.; Romberg, Gary; Hansen, Larry; Lutz, Ron

    1996-01-01

    An acoustic survey that consists of insertion loss and flow noise measurements was conducted at key locations around the circuit of a 3/8-scale automotive acoustic wind tunnel. Descriptions of the test, the instrumentation, and the wind tunnel facility are included in the current report, along with data obtained in the test in the form of 1/3-octave-band insertion loss and narrowband flow noise spectral data.

  4. 9- by 15-Foot Low Speed Wind Tunnel Acoustic Improvements Expanded Overview

    NASA Technical Reports Server (NTRS)

    Stephens, David

    2016-01-01

    The 9- by 15-Foot Low Speed Wind Tunnel (9x15 LSWT) at NASA Glenn Research Center was built in 1969 in the return leg of the 8- by 6-Foot Supersonic Wind Tunnel (8x6 SWT). The 8x6 SWT was completed in 1949 and acoustically treated to mitigate community noise issues in 1950. This treatment included the addition of a large muffler downstream of the 8x6 SWT test section and diffuser. The 9x15 LSWT was designed for performance testing of V/STOL aircraft models, but with the addition of the current acoustic treatment in 1986 the tunnel been used principally for acoustic and performance testing of aircraft propulsion systems. The present document describes an anticipated acoustic upgrade to be completed in 2017.

  5. Modeling the effects of wind tunnel wall absorption on the acoustic radiation characteristics of propellers

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.; Eversman, W.

    1986-01-01

    Finite element theory is used to calculate the acoustic field of a propeller in a soft walled circular wind tunnel and to compare the radiation patterns to the same propeller in free space. Parametric solutions are present for a "Gutin" propeller for a variety of flow Mach numbers, admittance values at the wall, microphone position locations, and propeller to duct radius ratios. Wind tunnel boundary layer is not included in this analysis. For wall admittance nearly equal to the characteristic value of free space, the free field and ducted propeller models agree in pressure level and directionality. In addition, the need for experimentally mapping the acoustic field is discussed.

  6. Modeling the effects of wind tunnel wall absorption on the acoustic radiation characteristics of propellers

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.; Eversman, W.

    1986-01-01

    Finite element theory is used to calculate the acoustic field of a propeller in a soft walled circular wind tunnel and to compare the radiation patterns to the same propeller in free space. Parametric solutions are present for a 'Gutin' propeller for a variety of flow Mach numbers, admittance values at the wall, microphone position locations, and propeller to duct radius ratios. Wind tunnel boundary layer is not included in this analysis. For wall admittance nearly equal to the characteristic value of free space, the free field and ducted propeller models agree in pressure level and directionality. In addition, the need for experimentally mapping the acoustic field is discussed.

  7. A four-element end-fire microphone array for acoustic measurements in wind tunnels

    NASA Technical Reports Server (NTRS)

    Soderman, P. T.; Noble, S. C.

    1974-01-01

    A prototype four-element end-fire microphone array was designed and built for evaluation as a directional acoustic receiver for use in large wind tunnels. The microphone signals were digitized, time delayed, summed, and reconverted to analog form in such a way as to create a directional response with the main lobe along the array axis. The measured array directivity agrees with theoretical predictions confirming the circuit design of the electronic control module. The array with 0.15 m (0.5 ft) microphone spacing rejected reverberations and background noise in the Ames 40- by 80-foot wind tunnel by 5 to 12 db for frequencies above 400 Hz.

  8. A comparison of acoustic predictions with model rotor test data from the NASA 14 x 22 ft wind tunnel

    NASA Astrophysics Data System (ADS)

    Schwindt, Christian J.; Fitzgerald, James M.

    A study to correlate the predictions of the NASA-developed ROTONET rotorcraft acoustic prediction code and the Sikorsky in-house rotorcraft acoustic prediction code with model wind tunnel tests is presented. The prediction methodology models thickness, steady and unsteady loading effects, with the unsteady loading derived from forward flight and simple wake models. The predictions have been compared with the acoustic data on the basis of similarity of the acoustic pressure time histories.

  9. Acoustical evaluation of the NASA Lewis 9 by 15 foot low speed wind tunnel

    NASA Technical Reports Server (NTRS)

    Dahl, Milo D.; Woodward, Richard P.

    1992-01-01

    The test section of the NASA Lewis 9- by 15-Foot Low Speed Wind Tunnel was acoustically treated to allow the measurement of acoustic sources located within the tunnel test section under simulated free field conditions. The treatment was designed for high sound absorption at frequencies above 250 Hz and to withstand tunnel airflow velocities up to 0.2 Mach. Evaluation tests with no tunnel airflow were conducted in the test section to assess the performance of the installed treatment. This performance would not be significantly affected by low speed airflow. Time delay spectrometry tests showed that interference ripples in the incident signal resulting from reflections occurring within the test section average from 1.7 dB to 3.2 dB wide over a 500 to 5150 Hz frequency range. Late reflections, from upstream and downstream of the test section, were found to be insignificant at the microphone measuring points. For acoustic sources with low directivity characteristics, decay with distance measurements in the test section showed that incident free field behavior can be measured on average with an accuracy of +/- 1.5 dB or better at source frequencies from 400 Hz to 10 kHz. The free field variations are typically much smaller with an omnidirectional source.

  10. Acoustic measurements of a large cavity in a wind tunnel

    NASA Technical Reports Server (NTRS)

    Scheiman, J.

    1978-01-01

    Acoustic measurements were made with inside and far-field microphones. Correlation of measured frequencies with available theories indicates that existing theories are applicable over a broader range than previously shown. The cavity configuration with a partial covering downstream amplified tonal intensities. The frequency of the tones depended on cavity size, not on cavity open area. Introducing upstream disturbances decreased the amplitude of the cavity tones.

  11. The Acoustic Environment of the NASA Glenn 9- by 15-foot Low-Speed Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Stephens, David B.

    2015-01-01

    The 9- by 15-Foot Low Speed Wind Tunnel is an acoustic testing facility with a long history of aircraft propulsion noise research. Due to interest in renovating the facility to support future testing of advanced quiet engine designs, a study was conducted to document the background noise level in the facility and investigate the sources of contaminating noise. The anechoic quality of the facility was also investigated using an interrupted noise method. The present report discusses these aspects of the noise environment in this facility.

  12. Acoustic Quality of the 40- by 80- Foot Wind Tunnel Test Section After Installation of a Deep Acoustic Lining

    NASA Technical Reports Server (NTRS)

    Soderman, Paul T.; Jaeger, Stephen M.; Hayes, Julie A.; Allen, Christopher S.

    2002-01-01

    A recessed, 42-inch deep acoustic lining has been designed and installed in the 40- by 80- Foot Wind Tunnel (40x80) test section to greatly improve the acoustic quality of the facility. This report describes the test section acoustic performance as determined by a detailed static calibration-all data were acquired without wind. Global measurements of sound decay from steady noise sources showed that the facility is suitable for acoustic studies of jet noise or similar randomly generated sound. The wall sound absorption, size of the facility, and averaging effects of wide band random noise all tend to minimize interference effects from wall reflections. The decay of white noise with distance was close to free field above 250 Hz. However, tonal sound data from propellers and fans, for example, will have an error band to be described that is caused by the sensitivity of tones to even weak interference. That error band could be minimized by use of directional instruments such as phased microphone arrays. Above 10 kHz, air absorption began to dominate the sound field in the large test section, reflections became weaker, and the test section tended toward an anechoic environment as frequency increased.

  13. Effect of wind tunnel acoustic modes on linear oscillating cascade aerodynamics

    NASA Technical Reports Server (NTRS)

    Buffum, Daniel H.; Fleeter, Sanford

    1993-01-01

    The aerodynamics of a biconvex airfoil cascade oscillating in torsion is investigated using the unsteady aerodynamic influence coefficient technique. For subsonic flow and reduced frequencies as large as 0.9, airfoil surface unsteady pressures resulting from oscillation of one of the airfoils are measured using flush-mounted high-frequency-response pressure transducers. The influence coefficient data are examined in detail and then used to predict the unsteady aerodynamics of a cascade oscillating at various interblade phase angles. These results are correlated with experimental data obtained in the traveling-wave mode of oscillation and linearized analysis predictions. It is found that the unsteady pressure disturbances created by an oscillating airfoil excite wind tunnel acoustic modes which have detrimental effects on the experimental data. Acoustic treatment is proposed to rectify this problem.

  14. Effect of wind tunnel acoustic modes on linear oscillating cascade aerodynamics

    NASA Technical Reports Server (NTRS)

    Buffum, D. H.; Fleeter, S.

    1994-01-01

    The aerodynamics of a biconvex airfoil cascade oscillating in torsion is investigated using the unsteady aerodynamic influence coefficient technique. For subsonic flow and reduced frequencies as large as 0.9, airfoil surface unsteady pressures resulting from oscillation of one of the airfoils are measured using flush-mounted high-frequency-response pressure transducers. The influence coefficient data are examined in detail and then used to predict the unsteady aerodynamics of a cascade oscillating at various interblade phase angles. These results are correlated with experimental data obtained in the traveling-wave mode of oscillation and linearized analysis predictions. It is found that the unsteady pressure disturbances created by an oscillating airfoil excite wind tunnel acoustic modes, which have detrimental effects on the experimental results. Acoustic treatment is proposed to rectify this problem.

  15. The design and commissioning of an acoustic liner for propeller noise testing in the ARA transonic wind tunnel

    NASA Astrophysics Data System (ADS)

    Wood, M. E.; Neuman, D. A.

    1991-12-01

    An acoustic liner was designed and manufactured for use in a transonic wind tunnel to provide an acoustically acceptable environment for propeller noise testing up to high subsonic Mach number. Details of the aerodynamic design and development are presented and calibration of the liner with propeller model support systems is included. It is shown how the design of the acoustic treatment was aided by the use of a theoretical model for the tunnel reverberant field. An acoustic development program was undertaken involving horn tests to improve the quality of the liner. The success of this is demonstrated by propeller noise results. These results also provided the basis for definition of the practical acoustic regime of a lined tunnel suitable for the accurate measurement of propeller noise.

  16. An evaluation of proposed acoustic treatments for the NASA LaRC 4 x 7 meter wind tunnel

    NASA Technical Reports Server (NTRS)

    Abrahamson, A. L.

    1985-01-01

    The NASA LaRC 4 x 7 Meter Wind Tunnel is an existing facility specially designed for powered low speed (V/STOL) testing of large scale fixed wing and rotorcraft models. The enhancement of the facility for scale model acoustic testing is examined. The results are critically reviewed and comparisons are drawn with a similar wind tunnel (the DNW Facility in the Netherlands). Discrepancies observed in the comparison stimulated a theoretical investigation using the acoustic finite element ADAM System, of the ways in which noise propagating around the tunnel circuit radiates into the open test section. The reasons for the discrepancies noted above are clarified and assists in the selection of acoustic treatment options for the facility.

  17. Design and Development of a Deep Acoustic Lining for the 40-by 80-Foot Wind Tunnel Test Section

    NASA Technical Reports Server (NTRS)

    Soderman, Paul T.; Schmitz, Fredric H.; Allen, Christopher S.; Jaeger, Stephen M.; Sacco, Joe N.; Mosher, Marianne; Hayes, Julie A.

    2002-01-01

    The work described in this report has made effective use of design teams to build a state-of-the-art anechoic wind-tunnel facility. Many potential design solutions were evaluated using engineering analysis, and computational tools. Design alternatives were then evaluated using specially developed testing techniques, Large-scale coupon testing was then performed to develop confidence that the preferred design would meet the acoustic, aerodynamic, and structural objectives of the project. Finally, designs were frozen and the final product was installed in the wind tunnel. The result of this technically ambitious project has been the creation of a unique acoustic wind tunnel. Its large test section (39 ft x 79 ft x SO ft), potentially near-anechoic environment, and medium subsonic speed capability (M = 0.45) will support a full range of aeroacoustic testing-from rotorcraft and other vertical takeoff and landing aircraft to the take-off/landing configurations of both subsonic and supersonic transports.

  18. A Study of Acoustic Reflections in Full-Scale Rotor Low Frequency Noise Measurements Acquired in Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Barbely, Natasha L.; Sim, Ben W.; Kitaplioglu, Cahit; Goulding, Pat, II

    2010-01-01

    Difficulties in obtaining full-scale rotor low frequency noise measurements in wind tunnels are addressed via residual sound reflections due to non-ideal anechoic wall treatments. Examples illustrated with the Boeing-SMART rotor test in the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel facility demonstrated that these reflections introduced distortions in the measured acoustic time histories that are not representative of free-field rotor noise radiation. A simplified reflection analysis, based on the method of images, is used to examine the sound measurement quality in such "less-than-anechoic" environment. Predictions of reflection-adjusted acoustic time histories are qualitatively shown to account for some of the spurious fluctuations observed in wind tunnel noise measurements

  19. Wind tunnel acoustic study of a propeller installed behind an airplane empennage: Data report

    NASA Technical Reports Server (NTRS)

    Wilby, J. F.; Wilby, E. G.

    1985-01-01

    The open test section of the NASA-Ames 7- by 10- ft wind tunnel was used for an acoustic test of a propeller mounted behind an airplane empennage. The empennage was attached to a model fuselage and the propeller with its electric motor drive was mounted separately so that the relative positions of empennage and propeller could be varied. A single vertical fin, and a V-tail with, and without, a dorsal fin configurations were used the model propeller had four blades (SR-1). Data were recorded at several locations for two tunnel flow speeds (45.7) and 62.5 m/s) and propeller speeds in the range 4000 to 8200 rpm. Data reduction was performed in narrowband and one-third octave band spectra, with emphasis on harmonics of the passage frequency blade. The influence of flow speed, propeller rpm, empennage configuration, axial and vertical separation between propeller axis and empennage centerline, and empennage angle of incidence on propeller harmonic levels and acoustic field directivity are studied.

  20. Acoustic measurements from a rotor blade-vortex interaction noise experiment in the German-Dutch Wind Tunnel (DNW)

    NASA Technical Reports Server (NTRS)

    Martin, Ruth M.; Splettstoesser, W. R.; Elliott, J. W.; Schultz, K.-J.

    1988-01-01

    Acoustic data are presented from a 40 percent scale model of the 4-bladed BO-105 helicopter main rotor, measured in the large European aeroacoustic wind tunnel, the DNW. Rotor blade-vortex interaction (BVI) noise data in the low speed flight range were acquired using a traversing in-flow microphone array. The experimental apparatus, testing procedures, calibration results, and experimental objectives are fully described. A large representative set of averaged acoustic signals is presented.

  1. Evaluation of the NASA Ames no. 1 7 by 10 foot wind tunnel as an acoustic test facility

    NASA Technical Reports Server (NTRS)

    Wilby, J. F.; Scharton, T. D.

    1975-01-01

    Measurements were made in the no. 1 7'x10' wind tunnel at NASA Ames Research Center, with the objectives of defining the acoustic characteristics and recommending minimum cost treatments so that the tunnel can be converted into an acoustic research facility. The results indicate that the noise levels in the test section are due to (a) noise generation in the test section, associated with the presence of solid bodies such as the pitot tube, and (b) propagation of acoustic energy from the fan. A criterion for noise levels in the test section is recommended, based on low-noise microphone support systems. Noise control methods required to meet the criterion include removal of hardware items for the test section and diffuser, improved design of microphone supports, and installation of acoustic treatment in the settling chamber and diffuser.

  2. A directional microphone array for acoustic studies of wind tunnel models

    NASA Technical Reports Server (NTRS)

    Soderman, P. T.; Noble, S. C.

    1974-01-01

    An end-fire microphone array that utilizes a digital time delay system has been designed and evaluated for measuring noise in wind tunnels. The directional response of both a four- and eight-element linear array of microphones has enabled substantial rejection of background noise and reverberations in the NASA Ames 40- by 80-foot wind tunnel. In addition, it is estimated that four- and eight-element arrays reject 6 and 9 dB, respectively, of microphone wind noise, as compared with a conventional omnidirectional microphone with nose cone. Array response to two types of jet engine models in the wind tunnel is presented. Comparisons of array response to loudspeakers in the wind tunnel and in free field are made.

  3. Acoustic Signatures of a Model Fan in the NASA-Lewis Anechoic Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Dietrich, D. A.; Heidmann, M. F.; Abbott, J. M.

    1977-01-01

    One-third octave band and narrowband spectra and continuous directivity patterns radiated from an inlet are presented over ranges of fan operating conditions, tunnel velocity, and angle of attack. Tunnel flow markedly reduced the unsteadiness and level of the blade passage tone, revealed the cutoff design feature of the blade passage tone, and exposed a lobular directivity pattern for the second harmonic tone. The full effects of tunnel flow are shown to be complete above a tunnel velocity of 20 meters/second. The acoustic signatures are also shown to be strongly affected by fan rotational speed, fan blade loading, and inlet angle of attack.

  4. Softwall acoustical characteristics and measurement capabilities of the NASA Lewis 9x15 foot low speed wind tunnel

    NASA Technical Reports Server (NTRS)

    Rentz, P. E.

    1976-01-01

    Acoustical characteristics and source directionality measurement capabilities of the wind tunnel in the softwall configuration were evaluated, using aerodynamically clean microphone supports. The radius of measurement was limited by the size of the test section, instead of the 3.0 foot (1 m) limitation of the hardwall test section. The wind-on noise level in the test section was reduced 10 dB. Reflections from the microphone support boom, after absorptive covering, induced measurement errors in the lower frequency bands. Reflections from the diffuser back wall were shown to be significant. Tunnel noise coming up the diffuser was postulated as being responsible, at least partially, for the wind-on noise in the test section and settling chamber. The near field characteristics of finite-sized sources and the theoretical response of a porous strip sensor in the presence of wind are presented.

  5. Acoustical modeling study of the open test section of the NASA Langley V/STOL wind tunnel

    NASA Technical Reports Server (NTRS)

    Ver, I. L.; Andersen, D. W.; Bliss, D. B.

    1975-01-01

    An acoustic model study was carried out to identify effective sound absorbing treatment of strategically located surfaces in an open wind tunnel test section. Also an aerodynamic study done concurrently, sought to find measures to control low frequency jet pulsations which occur when the tunnel is operated in its open test section configuration. The acoustical modeling study indicated that lining of the raised ceiling and the test section floor immediately below it, results in a substantial improvement. The aerodynamic model study indicated that: (1) the low frequency jet pulsations are most likely caused or maintained by coupling of aerodynamic and aeroacoustic phenomena in the closed tunnel circuit, (2) replacing the hard collector cowl with a geometrically identical but porous fiber metal surface of 100 mks rayls flow resistance does not result in any noticable reduction of the test section noise caused by the impingement of the turbulent flow on the cowl.

  6. Investigations of detail design issues for the high speed acoustic wind tunnel using a 60th scale model tunnel. Part 1: Tests with open circuits

    NASA Technical Reports Server (NTRS)

    Barna, P. Stephen

    1991-01-01

    This report summarizes the tests on the 1:60 scale model of the High Speed Acoustic Wind Tunnel (HSAWT) performed during the period of November 1989 to December 1990. Throughout the testing the tunnel was operated in the 'open circuit mode', that is when the airflow was induced by a powerful exhaust fan located outside the tunnel circuit. The tests were first performed with the closed test section and were subsequently repeated with the open test section. While operating with the open test section, a novel device, called the 'nozzle-diffuser,' was also tested in order to establish its usefulness of increasing pressure recovery in the first diffuser. The tests established the viability of the tunnel design. The flow distribution in each tunnel component was found acceptable and pressure recovery in the diffusers were found satisfactory. The diffusers appeared to operate without flow separation. All tests were performed at NASA LaRC.

  7. Low-disturbance wind tunnels

    NASA Technical Reports Server (NTRS)

    Beckwith, I. E.; Applin, Z. T.; Stainback, P. C.; Maestrello, L.

    1986-01-01

    During the past years, there was an extensive program under way at the Langley Research Center to upgrade the flow quality in several of the large wind tunnels. This effort has resulted in significant improvements in flow quality in these tunnels and has also increased the understanding of how and where changes in existing and new wind tunnels are most likely to yield the desired improvements. As part of this ongoing program, flow disturbance levels and spectra were measured in several Langley tunnels before and after modifications were made to reduce acoustic and vorticity fluctuations. A brief description of these disturbance control features is given for the Low-Turbulence Pressure Tunnel, the 4 x 7 Meter Tunnel, and the 8 Foot Transonic Pressure Tunnel. To illustrate typical reductions in disturbance levels obtained in these tunnels, data from hot-wire or acoustic sensors are presented. A concept for a subsonic quiet tunnel designed to study boundary layer stability and transition is also presented. Techniques developed at Langley in recent years to eliminate the high intensity and high-frequency acoustic disturbances present in all previous supersonic wind tunnels are described. In conclusion, the low-disturbance levels present in atmospheric flight can now be simulated in wind tunnels over the speed range from low subsonic through high supersonic.

  8. Comparison of acoustic data from a 102 mm conic nozzle as measured in the RAE 24-foot wind tunnel and the NASA Ames 40- by 80-foot wind tunnel

    NASA Technical Reports Server (NTRS)

    Atencio, A., Jr.; Mckie, J.

    1982-01-01

    A cooperative program between the Royal Aircraft Establishment (RAE), England, and the NASA Ames Research Center was initiated to compare acoustic measurements made in the RAE 24-foot wind tunnel and in the Ames 40- by 80-foot wind tunnel. The acoustic measurements were made in both facilities using the same 102 mm conical nozzle supplied by the RAE. The nozzle was tested by each organization using its respective jet test rig. The mounting hardware and nozzle exit conditions were matched as closely as possible. The data from each wind tunnel were independently analyzed by the respective organization. The results from these tests show good agreement. In both facilities, interference with acoustic measurement is evident at angles in the forward quadrant.

  9. Modification of the Ames 40- by 80-foot wind tunnel for component acoustic testing for the second generation supersonic transport

    NASA Technical Reports Server (NTRS)

    Schmitz, F. H.; Allmen, J. R.; Soderman, P. T.

    1994-01-01

    The development of a large-scale anechoic test facility where large models of engine/airframe/high-lift systems can be tested for both improved noise reduction and minimum performance degradation is described. The facility development is part of the effort to investigate economically viable methods of reducing second generation high speed civil transport noise during takeoff and climb-out that is now under way in the United States. This new capability will be achieved through acoustic modifications of NASA's second largest subsonic wind tunnel: the 40-by 80-Foot Wind Tunnel at the NASA Ames Research Center. Three major items are addressed in the design of this large anechoic and quiet wind tunnel: a new deep (42 inch (107 cm)) test section liner, expansion of the wind tunnel drive operating envelope at low rpm to reduce background noise, and other promising methods of improving signal-to-noise levels of inflow microphones. Current testing plans supporting the U.S. high speed civil transport program are also outlined.

  10. Comparison between design and installed acoustic characteristics of NASA Lewis 9- by 15-foot low-speed wind tunnel acoustic treatment

    NASA Technical Reports Server (NTRS)

    Dahl, Milo D.; Woodward, Richard P.

    1990-01-01

    The test section of the NASA Lewis 9- by 15-Foot Low-Speed Wind Tunnel was acoustically treated to allow the measurement of sound under simulated free-field conditions. The treatment was designed for high sound absorption at frequencies above 250 Hz and for withstanding the environmental conditions in the test section. In order to achieve the design requirements, a fibrous, bulk-absorber material was packed into removable panel sections. Each section was divided into two equal-depth layers packed with material to different bulk densities. The lower density was next to the facing of the treatment. The facing consisted of a perforated plate and screening material layered together. Sample tests for normal-incidence acoustic absorption were also conducted in an impedance tube to provide data to aid in the treatment design. Tests with no airflow, involving the measurement of the absorptive properties of the treatment installed in the 9- by 15-foot wind tunnel test section, combined the use of time-delay spectrometry with a previously established free-field measurement method. This new application of time-delay spectrometry enabled these free-field measurements to be made in nonanechoic conditions. The results showed that the installed acoustic treatment had absorption coefficients greater than 0.95 over the frequency range 250 Hz to 4 kHz. The measurements in the wind tunnel were in good agreement with both the analytical prediction and the impedance tube test data.

  11. Analysis of acoustic and entropy disturbances in a hypersonic wind tunnel

    NASA Astrophysics Data System (ADS)

    Schilden, Thomas; Schröder, Wolfgang; Ali, Syed Raza Christopher; Schreyer, Anne-Marie; Wu, Jie; Radespiel, Rolf

    2016-05-01

    The tunnel noise in a Mach 5.9 Ludwieg tube is determined by two methods, a newly developed cone-probe-DNS method and a reliable hot-wire-Pitot-probe method. The new method combines pressure and heat flux measurements using a cone probe and direct numerical simulation (DNS). The modal analysis is based on transfer functions obtained by the DNS to link the measured quantities to the tunnel noise. The measurements are performed for several unit-Reynolds numbers in the range of 5 ṡ 106 ≤ Re/m ≤ 16 ṡ 106 and probe positions to identify the sensitivities of tunnel noise. The DNS solutions show similar response mechanisms of the cone probe to incident acoustic and entropy waves which leads to high condition numbers of the transfer matrix such that a unique relationship between response and source mechanism can be only determined by neglecting the contribution of the non-acoustic modes to the pressure and heat flux fluctuations. The results of the cone-probe-DNS method are compared to a modal analysis based on the hot-wire-Pitot-probe method which provides reliable results in the frequency range less than 50 kHz. In this low frequency range the findings of the two different mode analyses agree well. At higher frequencies, the newly developed cone-probe-DNS method is still valid. The tunnel noise is dominated by the acoustic mode, since the entropy mode is lower by one order of magnitude and the vorticity mode can be neglected. The acoustic mode is approximately 0.5% at 30 kHz and the cone-probe-DNS data illustrate the acoustic mode to decrease and to asymptotically approach 0.2%.

  12. Acoustics Reflections of Full-Scale Rotor Noise Measurements in NFAC 40- by 80-Foot Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Barbely, Natasha Lydia; Kitaplioglu, Cahit; Sim, Ben W.

    2012-01-01

    The objective of current research is to identify the extent of acoustic time history distortions due to wind tunnel wall reflections. Acoustic measurements from the recent full-scale Boeing-SMART rotor test (Fig. 2) will be used to illustrate the quality of noise measurement in the NFAC 40- by 80-Foot Wind Tunnel test section. Results will be compared to PSU-WOPWOP predictions obtained with and without adjustments due to sound reflections off wind tunnel walls. Present research assumes a rectangular enclosure as shown in Fig. 3a. The Method of Mirror Images7 is used to account for reflection sources and their acoustic paths by introducing mirror images of the rotor (i.e. acoustic source), at each and every wall surface, to enforce a no-flow boundary condition at the position of the physical walls (Fig. 3b). While conventional approach evaluates the "combined" noise from both the source and image rotor at a single microphone position, an alternative approach is used to simplify implementation of PSU-WOPWOP for this reflection analysis. Here, an "equivalent" microphone position is defined with respect to the source rotor for each mirror image that effectively renders the reflection analysis to be a one rotor, multiple microphones problem. This alternative approach has the advantage of allowing each individual "equivalent" microphone, representing the reflection pulse from the associated wall surface, to be adjusted by the panel absorption coefficient illustrated in Fig. 1a. Note that the presence of parallel wall surfaces requires an infinite number of mirror images (Fig. 3c) to satisfy the no-flow boundary conditions. In the present analysis, up to four mirror images (per wall surface) are accounted to achieve convergence in the predicted time histories

  13. Acoustic evaluation of the Helmholtz resonator treatment in the NASA Lewis 8- by 6-foot supersonic wind tunnel

    NASA Technical Reports Server (NTRS)

    Heidelberg, Laurence J.; Gordon, Elliot B.

    1989-01-01

    The acoustic consequences of sealing the Helmholtz resonators of the NASA Lewis 8- by 6-Foot Supersonic Wind Tunnel (8x6 SWT) were experimentally evaluated. This resonator sealing was proposed in order to avoid entrapment of hydrogen during tests of advanced hydrogen-fueled engines. The resonators were designed to absorb energy in the 4- to 20-Hz range; thus, this investigation is primarily concerned with infrasound. Limited internal and external noise measurements were made at tunnel Mach numbers ranging from 0.5 to 2.0. Although the resonators were part of the acoustic treatment installed because of a community noise problem their sealing did not seem to indicate a reoccurrence of the problem would result. Two factors were key to this conclusion: (1) A large bulk treatment muffler downstream of the resonators was able to make up for much of the attenuation originally provided by the resonators, and (2) there was no noise source in the tunnel test section. The previous community noise problem occurred when a large ramjet was tested in an open-loop tunnel configuration. If a propulsion system producing high noise levels at frequencies of less than 10 Hz were tested, the conclusion on community noise would have to be reevaluated.

  14. Investigations of detail design issues for the high speed acoustic wind tunnel using a 60th scale model tunnel. Part 2: Tests with the closed circuit

    NASA Technical Reports Server (NTRS)

    Barna, P. Stephen

    1991-01-01

    This report summarizes the tests on the 1:60 scale model of the High Speed Acoustic Wind Tunnel (HSAWT) performed during the period June - August 1991. Throughout the testing the tunnel was operated in the 'closed circuit mode,' that is when the airflow was set up by an axial flow fan, which was located inside the tunnel circuit and was directly driven by a motor. The tests were first performed with the closed test section and were subsequently repeated with the open test section, the latter operating with the nozzle-diffuser at its optimum setting. On this subject, reference is made to the report (1) issued January 1991, under contract 17-GFY900125, which summarizes the result obtained with the tunnel operating in the 'open circuit mode.' The tests confirmed the viability of the tunnel design, and the flow distributions in most of the tunnel components were considered acceptable. There were found, however, some locations where the flow distribution requires improvement. This applies to the flow upstream of the fan where the flow was found skewed, thus affecting the flow downstream. As a result of this, the flow appeared separated at the end of the large diffuser at the outer side. All tests were performed at NASA LaRC.

  15. Cryogenic wind tunnels. III

    NASA Technical Reports Server (NTRS)

    Kilgore, Robert A.

    1987-01-01

    Specific problems pertaining to cryogenic wind tunnels, including LN(2) injection, GN(2) exhaust, thermal insulation, and automatic control are discussed. Thermal and other physical properties of materials employed in these tunnels, properties of cryogenic fluids, storage and transfer of liquid nitrogen, strength and toughness of metals and nonmetals at low temperatures, and material procurement and qualify control are considered. Safety concerns with cryogenic tunnels are covered, and models for cryogenic wind tunnels are presented, along with descriptions of major cryogenic wind-tunnel facilities the United States, Europe, and Japan. Problems common to wind tunnels, such as low Reynolds number, wall and support interference, and flow unsteadiness are outlined.

  16. Hardwall acoustical characteristics and measurement capabilities of the NASA Lewis 9 x 15 foot low speed wind tunnel

    NASA Technical Reports Server (NTRS)

    Rentz, P. E.

    1976-01-01

    Experimental evaluations of the acoustical characteristics and source sound power and directionality measurement capabilities of the NASA Lewis 9 x 15 foot low speed wind tunnel in the untreated or hardwall configuration were performed. The results indicate that source sound power estimates can be made using only settling chamber sound pressure measurements. The accuracy of these estimates, expressed as one standard deviation, can be improved from + or - 4 db to + or - 1 db if sound pressure measurements in the preparation room and diffuser are also used and source directivity information is utilized. A simple procedure is presented. Acceptably accurate measurements of source direct field acoustic radiation were found to be limited by the test section reverberant characteristics to 3.0 feet for omni-directional and highly directional sources. Wind-on noise measurements in the test section, settling chamber and preparation room were found to depend on the sixth power of tunnel velocity. The levels were compared with various analytic models. Results are presented and discussed.

  17. Wind-tunnel acoustic results of two rotor models with several tip designs

    NASA Technical Reports Server (NTRS)

    Martin, R. M.; Connor, A. B.

    1986-01-01

    A three-phase research program has been undertaken to study the acoustic signals due to the aerodynamic interaction of rotorcraft main rotors and tail rotors. During the first phase, two different rotor models with several interchangeable tips were tested in the Langley 4- by 7-Meter Tunnel on the U.S. Army rotor model system. An extensive acoustic data base was acquired, with special emphasis on blade-vortex interaction (BVI) noise. The details of the experimental procedure, acoustic data acquisition, and reduction are documented. The overall sound pressure level (OASPL) of the high-twist rotor systems is relatively insensitive to flight speed but generally increases with rotor tip-path-plane angle. The OASPL of the high-twist rotors is dominated by acoustic energy in the low-frequency harmonics. The OASPL of the low-twist rotor systems shows more dependence on flight speed than the high-twist rotors, in addition to being quite sensitive to tip-path-plane angle. An integrated band-limited sound pressure level, limited by 500 to 3000 Hz, is a useful metric to quantify the occurrence of BVI noise. The OASPL of the low-twist rotors is strongly influenced by the band-limited sound levels, indicating that the blade-vortex impulsive noise is a dominant noise source for this rotor design. The midfrequency acoustic levels for both rotors show a very strong dependence on rotor tip-path-plane angle. The tip-path-plane angle at which the maximum midfrequency sound level occurs consistently decreases with increasing flight speed. The maximum midfrequency sound level measured at a given location is constant regardless of the flight speed.

  18. Background Acoustics Levels in the 9x15 Wind Tunnel and Linear Array Testing

    NASA Technical Reports Server (NTRS)

    Stephens, David

    2011-01-01

    The background noise level in the 9x15 foot wind tunnel at NASA Glenn has been documented, and the results compare favorably with historical measurements. A study of recessed microphone mounting techniques was also conducted, and a recessed cavity with a micronic wire mesh screen reduces hydrodynamic noise by around 10 dB. A three-microphone signal processing technique can provide additional benefit, rejecting up to 15 dB of noise contamination at some frequencies. The screen and cavity system offers considerable benefit to test efficiency, although there are additional calibration requirements.

  19. Analysis of SRB reentry acoustic environments. [aeroacoustic spectra determined from wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Coffin, T.; Dandridge, R. E.; Haddock, U. W.

    1979-01-01

    Space shuttle solid rocket booster reentry aeroacoustic environments were estimated. Particular emphasis was given to the aft skirt/exit plane region for the Mach number regime 0.6 = or greater than M infinity = or less than 3.5. The analysis is based on the evaluation of wind tunnel model results in conjunction with Monte Carlo simulation of trajectory parameters. The experimental approach is described as well as the evaluation process utilized. Predicted environments are presented in terms of one-third octave band spectra representing space averaged values for critical regions on the solid rocket booster.

  20. Measuring Fast-Temporal Sediment Fluxes with an Analogue Acoustic Sensor: A Wind Tunnel Study

    PubMed Central

    Poortinga, Ate; van Minnen, Jan; Keijsers, Joep; Riksen, Michel; Goossens, Dirk; Seeger, Manuel

    2013-01-01

    In aeolian research, field measurements are important for studying complex wind-driven processes for land management evaluation and model validation. Consequently, there have been many devices developed, tested, and applied to investigate a range of aeolian-based phenomena. However, determining the most effective application and data analysis techniques is widely debated in the literature. Here we investigate the effectiveness of two different sediment traps (the BEST trap and the MWAC catcher) in measuring vertical sediment flux. The study was performed in a wind tunnel with sediment fluxes characterized using saltiphones. Contrary to most studies, we used the analogue output of five saltiphones mounted on top of each other to determine the total kinetic energy, which was then used to calculate aeolian sediment budgets. Absolute sediment losses during the experiments were determined using a balance located beneath the test tray. Test runs were conducted with different sand sizes and at different wind speeds. The efficiency of the two traps did not vary with the wind speed or sediment size but was affected by both the experimental setup (position of the lowest trap above the surface and number of traps in the saltation layer) and the technique used to calculate the sediment flux. Despite this, good agreement was found between sediment losses calculated from the saltiphone and those measured using the balance. The results of this study provide a framework for measuring sediment fluxes at small time resolution (seconds to milliseconds) in the field. PMID:24058512

  1. Aero-acoustic experimental verification of optimum configuration of variable-pitch fans for 40 x 80 foot subsonic wind tunnel

    NASA Technical Reports Server (NTRS)

    Lown, H.

    1977-01-01

    The aerodynamic and acoustic performance of two drive fan configurations (low-speed and high-speed variable pitch design) for a 40 x 80 foot wind tunnel were monitored. A 1/7-scale model was utilized. The necessary aero-acoustic data reduction computer program logic was supplied. Test results were evaluated, and the optimum configuration to be employed in the 40 foot full scale fan was recommended.

  2. Acoustic performance of two 1.83-meter-diameter fans designed for a wind-tunnel drive system

    NASA Technical Reports Server (NTRS)

    Soderman, P. R.; Page, V. R.

    1977-01-01

    A parametric study was made of the noise generated by two 1.83-m (6-ft) diameter fans operating up to a maximum pressure ratio of 1.03. One fan had 15 rotor blades, 23 stator blades, and a maximum rotational speed of 1200 rpm. The other fan had 9 rotor blades, 13 stator blades, and a maximum speed of 2,000 rpm. The fans were approximately 1/7-scale models of the 12.2-m (40-ft) diameter fans proposed for repowering the NASA-Ames 40- by 80 foot wind tunnel. The fans were operated individually in a 23.8-m (78-ft) long duct. Sound pressure levels in the duct were used to determine radiated acoustic power as fan speed, blade angle, and mass flow were varied. Results show that the low speed fan was slightly quieter than the high speed fan and, when scaled to full scale, would be 16 db quieter than the present wind tunnel fans. The fan noise varied directly with thrust regardless of whether thrust was varied by rotational speed or blade setting for the ranges studied.

  3. Acoustic Data Processing and Transient Signal Analysis for the Hybrid Wing Body 14- by 22-Foot Subsonic Wind Tunnel Test

    NASA Technical Reports Server (NTRS)

    Bahr, Christopher J.; Brooks, Thomas F.; Humphreys, William M.; Spalt, Taylor B.; Stead, Daniel J.

    2014-01-01

    An advanced vehicle concept, the HWB N2A-EXTE aircraft design, was tested in NASA Langley's 14- by 22-Foot Subsonic Wind Tunnel to study its acoustic characteristics for var- ious propulsion system installation and airframe con gurations. A signi cant upgrade to existing data processing systems was implemented, with a focus on portability and a re- duction in turnaround time. These requirements were met by updating codes originally written for a cluster environment and transferring them to a local workstation while en- abling GPU computing. Post-test, additional processing of the time series was required to remove transient hydrodynamic gusts from some of the microphone time series. A novel automated procedure was developed to analyze and reject contaminated blocks of data, under the assumption that the desired acoustic signal of interest was a band-limited sta- tionary random process, and of lower variance than the hydrodynamic contamination. The procedure is shown to successfully identify and remove contaminated blocks of data and retain the desired acoustic signal. Additional corrections to the data, mainly background subtraction, shear layer refraction calculations, atmospheric attenuation and microphone directivity corrections, were all necessary for initial analysis and noise assessments. These were implemented for the post-processing of spectral data, and are shown to behave as expected.

  4. The aeolian wind tunnel

    NASA Technical Reports Server (NTRS)

    Iversen, J. D.

    1991-01-01

    The aeolian wind tunnel is a special case of a larger subset of the wind tunnel family which is designed to simulate the atmospheric surface layer winds to small scale (a member of this larger subset is usually called an atmospheric boundary layer wind tunnel or environmental wind tunnel). The atmospheric boundary layer wind tunnel is designed to simulate, as closely as possible, the mean velocity and turbulence that occur naturally in the atmospheric boundary layer (defined as the lowest portion of the atmosphere, of the order of 500 m, in which the winds are most greatly affected by surface roughness and topography). The aeolian wind tunnel is used for two purposes: to simulate the physics of the saltation process and to model at small scale the erosional and depositional processes associated with topographic surface features. For purposes of studying aeolian effects on the surface of Mars and Venus as well as on Earth, the aeolian wind tunnel continues to prove to be a useful tool for estimating wind speeds necessary to move small particles on the three planets as well as to determine the effects of topography on the evolution of aeolian features such as wind streaks and dune patterns.

  5. A comparison of the acoustic and aerodynamic measurements of a model rotor tested in two anechoic wind tunnels

    NASA Technical Reports Server (NTRS)

    Boxwell, D. A.; Schmitz, F. H.; Splettstoesser, W. R.; Schultz, K. J.; Lewy, S.

    1986-01-01

    Two aeroacoustic facilities - the CEPRA 19 in France and the DNW in the Netherlands - are compared. The two facilities have unique acoustic characteristics that make them appropriate for acoustic testing of model-scale helicopter rotors. An identical pressure-instrumented model-scale rotor was tested in each facility and acoustic test results are compared with full-scale-rotor test results. Blade surface pressures measured in both tunnels were used to correlated nominal rotor operating conditions in each tunnel, and also used to assess the steadiness of the rotor in each tunnel's flow. In-the-flow rotor acoustic signatures at moderate forward speeds (35-50 m/sec) are presented for each facility and discussed in relation to the differences in tunnel geometries and aeroacoustic characteristics. Both reports are presented in appendices to this paper.

  6. A comparison of the acoustic and aerodynamic measurements of a model rotor tested in two anechoic wind tunnels

    NASA Technical Reports Server (NTRS)

    Boxwell, D. A.; Schmitz, F. H.; Splettstoesser, W. R.; Schultz, K. J.; Lewy, S.; Caplot, M.

    1986-01-01

    Two aeroacoustic facilities--the CEPRA 19 in France and the DNW in the Netherlands--are compared. The two facilities have unique acoustic characteristics that make them appropriate for acoustic testing of model-scale helicopter rotors. An identical pressure-instrumented model-scale rotor was tested in each facility and acoustic test results are compared with full-scale-rotor test results. Blade surface pressures measured in both tunnels were used to correlated nominal rotor operating conditions in each tunnel, and also used to assess the steadiness of the rotor in each tunnel's flow. In-the-flow rotor acoustic signatures at moderate forward speeds (35-50 m/sec) are presented for each facility and discussed in relation to the differences in tunnel geometries and aeroacoustic characteristics. Both reports are presented in appendices to this paper. ;.);

  7. Cryogenic wind tunnels. II

    NASA Technical Reports Server (NTRS)

    Kilgore, Robert A.

    1987-01-01

    The application of the cryogenic concept to various types of tunnels including Ludwieg tube tunnel, Evans clean tunnel, blowdown, induced-flow, and continuous-flow fan-driven tunnels is discussed. Benefits related to construction and operating costs are covered, along with benefits related to new testing capabilities. It is noted that cooling the test gas to very low temperatures increases Reynolds number by more than a factor of seven. From the energy standpoint, ambient-temperature fan-driven closed-return tunnels are considered to be the most efficient type of tunnel, while a large reduction in the required tunnel stagnation pressure can be achieved through cryogenic operation. Operating envelopes for three modes of operation for a cryogenic transonic pressure tunnel with a 2.5 by 2.5 test section are outlined. A computer program for calculating flow parameters and power requirements for wind tunnels with operating temperatures from saturation to above ambient is highlighted.

  8. The Design of Wind Tunnels and Wind Tunnel Propellers

    NASA Technical Reports Server (NTRS)

    Warner, Edward P; Norton, F H; Hebbert, C M

    1919-01-01

    Report discusses the theory of energy losses in wind tunnels, the application of the Drzewiecki theory of propeller design to wind tunnel propellers, and the efficiency and steadiness of flow in model tunnels of various types.

  9. Sound propagation from a simple source in a wind tunnel

    NASA Technical Reports Server (NTRS)

    Cole, J. E., III

    1975-01-01

    The nature of the acoustic field of a simple source in a wind tunnel under flow conditions was examined theoretically and experimentally. The motivation of the study was to establish aspects of the theoretical framework for interpreting acoustic data taken (in wind) tunnels using in wind microphones. Three distinct investigations were performed and are described in detail.

  10. Acoustic Modifications of the Ames 40x80 Foot Wind Tunnel and Test Techniques for High-Speed Research Model Testing

    NASA Technical Reports Server (NTRS)

    Soderman, Paul T.; Olson, Larry (Technical Monitor)

    1995-01-01

    The NFAC 40- by 80- Foot Wind Tunnel at Ames is being refurbished with a new, deep acoustic lining in the test section which will make the facility nearly anechoic over a large frequency range. The modification history, key elements, and schedule will be discussed. Design features and expected performance gains will be described. Background noise reductions will be summarized. Improvements in aeroacoustic research techniques have been developed and used recently at NFAC on several wind tunnel tests of High Speed Research models. Research on quiet inflow microphones and struts will be described. The Acoustic Survey Apparatus in the 40x80 will be illustrated. A special intensity probe was tested for source localization. Multi-channel, high speed digital data acquisition is now used for acoustics. And most important, phased microphone arrays have been developed and tested which have proven to be very powerful for source identification and increased signal-to-noise ratio. Use of these tools for the HEAT model will be illustrated. In addition, an acoustically absorbent symmetry plane was built to satisfy the HEAT semispan aerodynamic and acoustic requirements. Acoustic performance of that symmetry plane will be shown.

  11. Flight effects on the aerodynamic and acoustic characteristics of inverted profile coannular nozzles, volume 1. [supersonic cruise aircraft research wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Kozlowski, H.; Packman, A. B.

    1978-01-01

    Jet noise spectra obtained at static conditions from an acoustic wind tunnel and an outdoor facility are compared. Data curves are presented for (1) the effect of relative velocity on OASPL directivity (all configurations); (2) the effect of relative velocity on noise spectra (all configurations); (3) the effect of velocity on PNL directivity (coannular nozzle configurations); (4) nozzle exhaust plume velocity profiles; and (5) the effect of relative velocity on aerodynamic performance.

  12. The cryogenic wind tunnel

    NASA Technical Reports Server (NTRS)

    Kilgore, R. A.

    1976-01-01

    Based on theoretical studies and experience with a low speed cryogenic tunnel and with a 1/3-meter transonic cryogenic tunnel, the cryogenic wind tunnel concept was shown to offer many advantages with respect to the attainment of full scale Reynolds number at reasonable levels of dynamic pressure in a ground based facility. The unique modes of operation available in a pressurized cryogenic tunnel make possible for the first time the separation of Mach number, Reynolds number, and aeroelastic effects. By reducing the drive-power requirements to a level where a conventional fan drive system may be used, the cryogenic concept makes possible a tunnel with high productivity and run times sufficiently long to allow for all types of tests at reduced capital costs and, for equal amounts of testing, reduced total energy consumption in comparison with other tunnel concepts.

  13. Acoustical properties of materials and muffler configurations for the 80 by 120 foot wind tunnel

    NASA Technical Reports Server (NTRS)

    Scharton, T. D.; Sneddon, M. D.

    1977-01-01

    Techniques for measuring the impedance of the muffler configurations and of porous plates with grazing flow were investigated and changes in the configuration parameters to enhance acoustic performance are explored. The feasibility of a pulse reflection technique for measuring the impedance of built-up structures in situ was demonstrated. A second technique involving the use of an open-end impedance tube with grazing flow was used to obtain detailed design data for the perforated plate configuration. Acoustic benefits associated with configuration changes such as curving the baffles, spacing and staggering baffle partitions, and techniques for alleviating baffle self-generated noise are described.

  14. Modelling of wind tunnel wall effects on the radiation characteristics of acoustic sources

    NASA Technical Reports Server (NTRS)

    Eversman, W.; Baumeister, K. J.

    1984-01-01

    It is pointed out that the relatively high fuel economy available from propeller-driven aircraft has renewed interest in high speed, highly loaded multiple blade turboprop propulsion systems. Undesirable features related to community noise and the high intensity cabin noise have stimulated new research on the acoustic characteristics of turboprops. The present investigation has the objective to develop a mathematical model of the essential features of the radiation of acoustic disturbances from propellers in a duct and in free space in order to quantify the success with which duct testing can be expected to approximate free field conditions. In connection with the importance of source directionality, a detailed model is considered which consists of a finite element representation of the Gutin propeller theory valid in both the near and far field.

  15. Qualitative Assessment of the Acoustic Disturbance Environment in the NASA LaRC 20-Inch MACH 6 Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Horvath, Thomas J.; Berry, Scott A.; Hamilton, H. Harris

    2001-01-01

    An experimental investigation was conducted on a 5-degree-half-angle cone with a flare in a conventional Mach 6 wind tunnel to examine the effect of facility noise on boundary layer transition. The effect of tunnel noise was inferred by comparing transition onset locations determined from the present test to that previously obtained in a Mach 6 quiet tunnel. Together, the two sets of experiments are believed to represent the first direct comparison of transition onset between a conventional and a quiet hypersonic wind tunnel using a common test model. In the present conventional hypersonic tunnel experiment, adiabatic wall temperatures were measured and heat transfer distributions were inferred on the cone flare model at zero degree angle of attack over a range of length Reynolds numbers (2 x 10(exp 6) to 10 x 10(exp 6)) which resulted in laminar and turbulent flow. Wall-to-total temperature ratio for the transient heating measurements and the adiabatic wall temperature measurements were 0.69 and 0.86, respectively. The cone flare nosetip radius was varied from 0.0001 to 0.125-inch to examine the effects of bluntness on transition onset. At comparable freestream conditions the transition onset Reynolds number obtained on the cone flare model in the conventional "noisy" tunnel was approximately 25% lower than that measured in the low disturbance tunnel.

  16. Experimental localization of an acoustic sound source in a wind-tunnel flow by using a numerical time-reversal technique.

    PubMed

    Padois, Thomas; Prax, Christian; Valeau, Vincent; Marx, David

    2012-10-01

    The possibility of using the time-reversal technique to localize acoustic sources in a wind-tunnel flow is investigated. While the technique is widespread, it has scarcely been used in aeroacoustics up to now. The proposed method consists of two steps: in a first experimental step, the acoustic pressure fluctuations are recorded over a linear array of microphones; in a second numerical step, the experimental data are time-reversed and used as input data for a numerical code solving the linearized Euler equations. The simulation achieves the back-propagation of the waves from the array to the source and takes into account the effect of the mean flow on sound propagation. The ability of the method to localize a sound source in a typical wind-tunnel flow is first demonstrated using simulated data. A generic experiment is then set up in an anechoic wind tunnel to validate the proposed method with a flow at Mach number 0.11. Monopolar sources are first considered that are either monochromatic or have a narrow or wide-band frequency content. The source position estimation is well-achieved with an error inferior to the wavelength. An application to a dipolar sound source shows that this type of source is also very satisfactorily characterized. PMID:23039435

  17. Wind tunnel wall interference

    NASA Technical Reports Server (NTRS)

    Newman, Perry A.; Mineck, Raymond E.; Barnwell, Richard W.; Kemp, William B., Jr.

    1986-01-01

    About a decade ago, interest in alleviating wind tunnel wall interference was renewed by advances in computational aerodynamics, concepts of adaptive test section walls, and plans for high Reynolds number transonic test facilities. Selection of NASA Langley cryogenic concept for the National Transonic Facility (NTF) tended to focus the renewed wall interference efforts. A brief overview and current status of some Langley sponsored transonic wind tunnel wall interference research are presented. Included are continuing efforts in basic wall flow studies, wall interference assessment/correction procedures, and adaptive wall technology.

  18. Instrumentation in wind tunnels

    NASA Technical Reports Server (NTRS)

    Takashima, K.

    1986-01-01

    Requirements in designing instrumentation systems and measurements of various physical quantities in wind tunnels are surveyed. Emphasis is given to sensors used for measuring pressure, temperature, and angle, and the measurements of air turbulence and boundary layers. Instrumentation in wind tunnels require accuracy, fast response, diversity and operational simplicity. Measurements of force, pressure, attitude angle, free flow, pressure distribution, and temperature are illustrated by a table, and a block diagram. The LDV (laser Doppler velocimeter) method for measuring air turbulence and flow velocity and measurement of skin friction and flow fields using laser holograms are discussed. The future potential of these techniques is studied.

  19. Two-dimensional wind tunnel

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Information on the Japanese National Aerospace Laboratory two dimensional transonic wind tunnel, completed at the end of 1979 is presented. Its construction is discussed in detail, and the wind tunnel structure, operation, test results, and future plans are presented.

  20. Acoustic characteristics of a large scale wind-tunnel model of a jet flap aircraft

    NASA Technical Reports Server (NTRS)

    Falarski, M. D.; Aiken, T. N.; Aoyagi, K.

    1975-01-01

    The expanding-duct jet flap (EJF) concept is studied to determine STOL performance in turbofan-powered aircraft. The EJF is used to solve the problem of ducting the required volume of air into the wing by providing an expanding cavity between the upper and lower surfaces of the flap. The results are presented of an investigation of the acoustic characteristics of the EJF concept on a large-scale aircraft model powered by JT15D engines. The noise of the EJF is generated by acoustic dipoles as shown by the sixth power dependence of the noise on jet velocity. These sources result from the interaction of the flow turbulence with flap of internal and external surfaces and the trailing edges. Increasing the trailing edge jet from 70 percent span to 100 percent span increased the noise 2 db for the equivalent nozzle area. Blowing at the knee of the flap rather than the trailing edge reduced the noise 5 to 10 db by displacing the jet from the trailing edge and providing shielding from high-frequency noise. Deflecting the flap and varying the angle of attack modified the directivity of the underwing noise but did not affect the peak noise. A forward speed of 33.5 m/sec (110 ft/sec) reduced the dipole noise less than 1 db.

  1. Initial Investigation of the Acoustics of a Counter-Rotating Open Rotor Model with Historical Baseline Blades in a Low-Speed Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Elliott, David M.

    2012-01-01

    A counter-rotating open rotor scale model was tested in the NASA Glenn Research Center 9- by 15-Foot Low-Speed Wind Tunnel (LSWT). This model used a historical baseline blade set with which modern blade designs will be compared against on an acoustic and aerodynamic performance basis. Different blade pitch angles simulating approach and takeoff conditions were tested, along with angle-of-attack configurations. A configuration was also tested in order to determine the acoustic effects of a pylon. The shaft speed was varied for each configuration in order to get data over a range of operability. The freestream Mach number was also varied for some configurations. Sideline acoustic data were taken for each of these test configurations.

  2. Wind Tunnel Measurements of Windscreen Performance

    NASA Astrophysics Data System (ADS)

    Maniet, Edward R., Jr

    2001-10-01

    Wind noise is recognized as one the primary environmental factors that limits the performance of battlefield acoustic sensors. Microphone windscreens are regularly used to reduce wind noise and the characterization of their performance is an important component of the acoustic sensor design, Textron Systems has extensive experience studying the performance of windscreens and have developed test methodology that allows for repeatable measurements in a controlled environment. Wind noise measurements are performed using a high-speed/laminar-flow, low-noise wind tunnel with an anechoic test section. A special test section is added to the wind tunnel to generate a turbulent flow. The turbulent wind velocity spectrum is measured using multi-axis hot wire anemometers. Comparative performance measurements of several windscreen designs are presented.

  3. Dry wind tunnel system

    NASA Technical Reports Server (NTRS)

    Chen, Ping-Chih (Inventor)

    2013-01-01

    This invention is a ground flutter testing system without a wind tunnel, called Dry Wind Tunnel (DWT) System. The DWT system consists of a Ground Vibration Test (GVT) hardware system, a multiple input multiple output (MIMO) force controller software, and a real-time unsteady aerodynamic force generation software, that is developed from an aerodynamic reduced order model (ROM). The ground flutter test using the DWT System operates on a real structural model, therefore no scaled-down structural model, which is required by the conventional wind tunnel flutter test, is involved. Furthermore, the impact of the structural nonlinearities on the aeroelastic stability can be included automatically. Moreover, the aeroservoelastic characteristics of the aircraft can be easily measured by simply including the flight control system in-the-loop. In addition, the unsteady aerodynamics generated computationally is interference-free from the wind tunnel walls. Finally, the DWT System can be conveniently and inexpensively carried out as a post GVT test with the same hardware, only with some possible rearrangement of the shakers and the inclusion of additional sensors.

  4. Wind Tunnel Balances

    NASA Technical Reports Server (NTRS)

    Warner, Edward P; Norton, F H

    1920-01-01

    Report embodies a description of the balance designed and constructed for the use of the National Advisory Committee for Aeronautics at Langley Field, and also deals with the theory of sensitivity of balances and with the errors to which wind tunnel balances of various types are subject.

  5. Aeroacoustic research in wind tunnels: A status report

    NASA Technical Reports Server (NTRS)

    Bender, J.; Arndt, R. E. A.

    1973-01-01

    The increasing attention given to aerodynamically generated noise brings into focus the need for quality experimental research in this area. To meet this need several specialized anechoic wind tunnels have been constructed. In many cases, however, budgetary constraints and the like make it desirable to use conventional wind tunnels for this work. Three basic problems are inherent in conventional facilities: (1) high background noise, (2) strong frequency dependent reverberation effects, and (3) unique instrumentation problems. The known acoustic characteristics of several conventional wind tunnels are evaluated and data obtained in a smaller 4- x 5-foot wind tunnel which is convertible from a closed jet to an open jet mode are presented. The data from these tunnels serve as a guideline for proposed modifications to a 7- x 10-foot wind tunnel. Consideration is given to acoustic treatment in several different portions of the wind tunnel.

  6. V/STOL wind-tunnel testing

    NASA Technical Reports Server (NTRS)

    Koenig, D. G.

    1984-01-01

    Factors influencing effective program planning for V/STOL wind-tunnel testing are discussed. The planning sequence itself, which includes a short checklist of considerations that could enhance the value of the tests, is also described. Each of the considerations, choice of wind tunnel, type of model installation, model development and test operations, is discussed, and examples of appropriate past and current V/STOL test programs are provided. A short survey of the moderate to large subsonic wind tunnels is followed by a review of several model installations, from two-dimensional to large-scale models of complete aircraft configurations. Model sizing, power simulation, and planning are treated, including three areas is test operations: data-acquisition systems, acoustic measurements in wind tunnels, and flow surveying.

  7. Particle surface area dependence of mineral dust in immersion freezing mode: investigations with freely suspended drops in an acoustic levitator and a vertical wind tunnel

    NASA Astrophysics Data System (ADS)

    Diehl, K.; Debertshäuser, M.; Eppers, O.; Schmithüsen, H.; Mitra, S. K.; Borrmann, S.

    2014-11-01

    The heterogeneous freezing temperatures of supercooled drops were measured using an acoustic levitator. This technique allows one to freely suspend single drops in the air without any wall contact. Heterogeneous nucleation by two types of illite (illite IMt1 and illite NX) and a montmorillonite sample was investigated in the immersion mode. Drops of 1 mm in radius were monitored by a video camera while cooled down to -28 °C to simulate freezing within the tropospheric temperature range. The surface temperature of the drops was contact-free, determined with an infrared thermometer; the onset of freezing was indicated by a sudden increase of the drop surface temperature. For comparison, measurements with one particle type (illite NX) were additionally performed in the Mainz vertical wind tunnel with drops of 340 μm radius freely suspended. Immersion freezing was observed in a temperature range between -13 and -26 °C as a function of particle type and particle surface area immersed in the drops. Isothermal experiments in the wind tunnel indicated that after the cooling stage freezing still proceeds, at least during the investigated time period of 30 s. The results were evaluated by applying two descriptions of heterogeneous freezing, the stochastic and the singular model. Although the wind tunnel results do not support the time-independence of the freezing process both models are applicable for comparing the results from the two experimental techniques.

  8. 20-Foot Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1941-01-01

    The large structure on the left of the photograph is the Free-Spinning Wind Tunnel in which dynamic scale models of modern airplanes are tested to determine their spinning characteristics and ability to recover from spins from movement of the control surfaces. From the information obtained in this manner, the spin recovery characteristics of the full-scale airplane may be predicted. The large sphere on the right is 60 feet in diameter and houses the NACA 12-Foot Free-Flight Wind Tunnel in which dynamic scale models of airplanes are flown in actual controlled flight to provide information from which the stability characteristics of the full-scale airplane may be predicted.

  9. High-speed Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Ackeret, J

    1936-01-01

    Wind tunnel construction and design is discussed especially in relation to subsonic and supersonic speeds. Reynolds Numbers and the theory of compressible flows are also taken into consideration in designing new tunnels.

  10. Wind turbine acoustics

    NASA Technical Reports Server (NTRS)

    Hubbard, Harvey H.; Shepherd, Kevin P.

    1990-01-01

    Available information on the physical characteristics of the noise generated by wind turbines is summarized, with example sound pressure time histories, narrow- and broadband frequency spectra, and noise radiation patterns. Reviewed are noise measurement standards, analysis technology, and a method of characterizing wind turbine noise. Prediction methods are given for both low-frequency rotational harmonics and broadband noise components. Also included are atmospheric propagation data showing the effects of distance and refraction by wind shear. Human perception thresholds, based on laboratory and field tests, are given. Building vibration analysis methods are summarized. The bibliography of this report lists technical publications on all aspects of wind turbine acoustics.

  11. Aspects of investigating STOL noise using large scale wind tunnel models

    NASA Technical Reports Server (NTRS)

    Falarski, M. D.; Koenig, D. G.; Soderman, P. T.

    1972-01-01

    The applicability of the NASA Ames 40- by 80-ft wind tunnel for acoustic research on STOL concepts has been investigated. The acoustic characteristics of the wind tunnel test section has been studied with calibrated acoustic sources. Acoustic characteristics of several large-scale STOL models have been studied both in the free-field and wind tunnel acoustic environments. The results indicate that the acoustic characteristics of large-scale STOL models can be measured in the wind tunnel if the test section acoustic environment and model acoustic similitude are taken into consideration. The reverberant field of the test section must be determined with an acoustically similar noise source. Directional microphone and extrapolation of near-field data to far-field are some of the techniques being explored as possible solutions to the directivity loss in a reverberant field. The model sound pressure levels must be of sufficient magnitude to be discernable from the wind tunnel background noise.

  12. The Langley Wind Tunnel Enterprise

    NASA Technical Reports Server (NTRS)

    Paulson, John W., Jr.; Kumar, Ajay; Kegelman, Jerome T.

    1998-01-01

    After 4 years of existence, the Langley WTE is alive and growing. Significant improvements in the operation of wind tunnels have been demonstrated and substantial further improvements are expected when we are able to truly address and integrate all the processes affecting the wind tunnel testing cycle.

  13. 5-Foot Vertical Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Construction of 5-Foot Vertical Wind Tunnel. The 5-Foot Vertical Wind Tunnel was built to study spinning characteristics of aircraft. It was an open throat tunnel capable of a maximum speed of 80 mph. NACA engineer Charles H. Zimmerman designed the tunnel starting in 1928. Construction was completed in December 1929. It was one of two tunnels which replaced the original Atmospheric Wind Tunnel (The other was the 7x10-Foot Wind Tunnel.). In NACA TR 387 (p. 499), Carl Wenzinger and Thomas Harris report that 'the tunnel passages are constructed of 1/8-inch sheet iron, stiffened with angle iron and bolted together at the corners. The over-all dimensions are: Height 31 feet 2 inches; length, 20 feet 3 inches; width, 10 feet 3 inches.' The tunnel was partially constructed in the Langley hanger as indicated by the aircraft in the background. Published in NACA TR 387, 'The Vertical Wind Tunnel of the National Advisory Committee for Aeronautics,' by Carl J. Wenzinger and Thomas A. Harris, 1931.

  14. Acoustic Performance of the GEAE UPS Research Fan in the NASA Glenn 9- by 15-Foot Low-Speed Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Woodward, Richard P.; Hughes, Christopher E.

    2012-01-01

    A model advanced turbofan was acoustically tested in the NASA Glenn 9- by 15-Foot Low-Speed Wind Tunnel in 1994. The Universal Propulsion Simulator fan was designed and manufactured by General Electric Aircraft Engines, and included an active core, as well as bypass, flow paths. The fan was tested with several rotors featuring unswept, forward-swept and aft-swept designs of both metal and composite construction. Sideline acoustic data were taken with both hard and acoustically treated walls in the flow passages. The fan was tested within an airflow at a Mach number of 0.20, which is representative of aircraft takeoff/approach conditions. All rotors showed similar aerodynamic performance. However, the composite rotors typically showed higher noise levels than did corresponding metal rotors. Aft and forward rotor sweep showed at most modest reductions of transonic multiple pure tone levels. However, rotor sweep often introduced increased rotor-stator interaction tone levels. Broadband noise was typically higher for the composite rotors and also for the aft-swept metal rotor. Transonic MPT generation was reduced with increasing fan axis angle of attack (AOA); however, higher downstream noise levels did increase with AOA resulting in higher overall Effective Perceived Noise Level.

  15. The virtual wind tunnel

    NASA Technical Reports Server (NTRS)

    Bryson, Steve; Levit, Creon

    1992-01-01

    Consideration is given to the design and implementaion of a virtual environment linked to a graphics workstation for the visualization of complex fluid flows. The user wears a stereo head-tracked display which displays 3D information and an instrumented glove to intuitively position flow-visualization tools. The idea is to create for the user an illusion that he or she is actually in the flow manipulating visualization tools. The user's presence does not disturb the flow so that sensitive flow areas can be easily investigated. The flow is precomputed and can be investigated at any length scale and with control over time. Particular attention is given to the visualization structures and their interfaces in the virtual environment, hardware and software, and the performance of the virtual wind tunnel using flow past a tapered cylinder as an example.

  16. Production of oscillatory flow in wind tunnels

    NASA Astrophysics Data System (ADS)

    Al-Asmi, K.; Castro, I. P.

    1993-06-01

    A method for producing oscillatory flow in open-circuit wind tunnels driven by centrifugal fans is described. Performance characteristics of a new device installed on two such tunnels of greatly differing size are presented. It is shown that sinusoidal variations of the working section flow, having peak-to-peak amplitudes up to at least 30 percent of the mean flow speed and frequencies up to, typically, that corresponding to the acoustic quarter-wave-length frequency determined by the tunnel size, can be obtained with negligible harmonic distortion or acoustic noise difficulties. A brief review of the various methods that have been used previously is included, and the advantages and disadvantages of these different techniques are highlighted. The present technique seems to represent a significant improvement over many of them.

  17. Advancing Test Capabilities at NASA Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Bell, James

    2015-01-01

    NASA maintains twelve major wind tunnels at three field centers capable of providing flows at 0.1 M 10 and unit Reynolds numbers up to 45106m. The maintenance and enhancement of these facilities is handled through a unified management structure under NASAs Aeronautics and Evaluation and Test Capability (AETC) project. The AETC facilities are; the 11x11 transonic and 9x7 supersonic wind tunnels at NASA Ames; the 10x10 and 8x6 supersonic wind tunnels, 9x15 low speed tunnel, Icing Research Tunnel, and Propulsion Simulator Laboratory, all at NASA Glenn; and the National Transonic Facility, Transonic Dynamics Tunnel, LAL aerothermodynamics laboratory, 8 High Temperature Tunnel, and 14x22 low speed tunnel, all at NASA Langley. This presentation describes the primary AETC facilities and their current capabilities, as well as improvements which are planned over the next five years. These improvements fall into three categories. The first are operations and maintenance improvements designed to increase the efficiency and reliability of the wind tunnels. These include new (possibly composite) fan blades at several facilities, new temperature control systems, and new and much more capable facility data systems. The second category of improvements are facility capability advancements. These include significant improvements to optical access in wind tunnel test sections at Ames, improvements to test section acoustics at Glenn and Langley, the development of a Supercooled Large Droplet capability for icing research, and the development of an icing capability for large engine testing. The final category of improvements consists of test technology enhancements which provide value across multiple facilities. These include projects to increase balance accuracy, provide NIST-traceable calibration characterization for wind tunnels, and to advance optical instruments for Computational Fluid Dynamics (CFD) validation. Taken as a whole, these individual projects provide significant

  18. Introduction to cryogenic wind tunnels

    NASA Technical Reports Server (NTRS)

    Goodyer, M. J.

    1985-01-01

    The background to the evolution of the cryogenic wind tunnel is outlined, with particular reference to the late 60's/early 70's when efforts were begun to re-equip with larger wind tunnels. The problems of providing full scale Reynolds numbers in transonic testing were proving particularly intractible, when the notion of satisfying the needs with the cryogenic tunnel was proposed, and then adopted. The principles and advantages of the cryogenic tunnel are outlined, along with guidance on the coolant needs when this is liquid nitrogen, and with a note on energy recovery. Operational features of the tunnels are introduced with reference to a small low speed tunnel. Finally the outstanding contributions are highlighted of the 0.3-Meter Transonic Cryogenic Tunnel (TCT) at NASA Langley Research Center, and its personnel, to the furtherance of knowledge and confidence in the concept.

  19. Flatback airfoil wind tunnel experiment.

    SciTech Connect

    Mayda, Edward A.; van Dam, C.P.; Chao, David D.; Berg, Dale E.

    2008-04-01

    A computational fluid dynamics study of thick wind turbine section shapes in the test section of the UC Davis wind tunnel at a chord Reynolds number of one million is presented. The goals of this study are to validate standard wind tunnel wall corrections for high solid blockage conditions and to reaffirm the favorable effect of a blunt trailing edge or flatback on the performance characteristics of a representative thick airfoil shape prior to building the wind tunnel models and conducting the experiment. The numerical simulations prove the standard wind tunnel corrections to be largely valid for the proposed test of 40% maximum thickness to chord ratio airfoils at a solid blockage ratio of 10%. Comparison of the computed lift characteristics of a sharp trailing edge baseline airfoil and derived flatback airfoils reaffirms the earlier observed trend of reduced sensitivity to surface contamination with increasing trailing edge thickness.

  20. Acoustic characteristics of a large-scale wind tunnel model of an upper-surface blown flap transport having two engines

    NASA Technical Reports Server (NTRS)

    Falarski, M. D.; Aoyagi, K.; Koenig, D. G.

    1973-01-01

    The upper-surface blown (USB) flap as a powered-lift concept has evolved because of the potential acoustic shielding provided when turbofan engines are installed on a wing upper surface. The results from a wind tunnel investigation of a large-scale USB model powered by two JT15D-1 turbofan engines are-presented. The effects of coanda flap extent and deflection, forward speed, and exhaust nozzle configuration were investigated. To determine the wing shielding the acoustics of a single engine nacelle removed from the model were also measured. Effective shielding occurred in the aft underwing quadrant. In the forward quadrant the shielding of the high frequency noise was counteracted by an increase in the lower frequency wing-exhaust interaction noise. The fuselage provided shielding of the opposite engine noise such that the difference between single and double engine operation was 1.5 PNdB under the wing. The effects of coanda flap deflection and extent, angle of attack, and forward speed were small. Forward speed reduced the perceived noise level (PNL) by reducing the wing-exhaust interaction noise.

  1. 5-Foot Vertical Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Schematic drawing of 5-Foot Vertical Wind Tunnel. Carl Wenzinger and Thomas Harris describe the tunnel in NACA TR No. 387: 'The tunnel has an open jet, an open test chamber, and a closed return passage. ... The air passes through the test section in a downward direction then enters the exit cone and passes through the first set of guide vanes to a propeller. From here it passes, by way of the return passage, through the successive sets of guide vanes at the corners, then through the honeycomb, and finally through the entrance cone.' In an earlier report, NACA TR 387, Carl Wenzinger and Thomas Harris supply this description of the tunnel: 'The vertical open-throat wind tunnel of the National Advisory Committee for Aeronautics ... was built mainly for studying the spinning characteristics of airplane models, but may be used as well for the usual types of wind-tunnel tests. A special spinning balance is being developed to measure the desired forces and moments with the model simulating the actual spin of an airplane. Satisfactory air flow has been attained with a velocity that is uniform over the jet to within 0.5%. The turbulence present in the tunnel has been compared with that of several other tunnels by means of the results of sphere drag tests and was found to average well with the values of those tunnels. Included also in the report are comparisons of results of stable autorotation and of rolling-moment tests obtained both in the vertical tunnel and in the old horizontal 5-foot atmospheric tunnel.' The design of a vertical tunnel having a 5-foot diameter jet was accordingly started by the National Advisory Committee for Aeronautics in 1928. Actual construction of the new tunnel was completed in 1930, and the calibration tests were then made.'

  2. Wind turbine acoustic standards

    NASA Technical Reports Server (NTRS)

    Stephens, D. G.; Shepherd, K. P.; Grosveld, F.

    1981-01-01

    A program is being conducted to develop noise standards for wind turbines which minimize annoyance and which can be used to design specifications. The approach consists of presenting wind turbine noise stimuli to test subjects in a laboratory listening chamber. The responses of the subjects are recorded for a range of stimuli which encompass the designs, operating conditions, and ambient noise levels of current and future installations. Results to date have established the threshold of detectability for a range of impulsive stimuli of the type associated with blade/tower wake interactions. The status of the ongoing psychoacoustic tests, the subjective data, and the approach to the development of acoustic criteria/standards are described.

  3. Mitigation of wind tunnel wall interactions in subsonic cavity flows

    DOE PAGESBeta

    Wagner, Justin L.; Casper, Katya Marie; Beresh, Steven J.; Henfling, John F.; Spillers, Russell Wayne; Pruett, Brian Owen Matthew

    2015-03-06

    In this study, the flow over an open aircraft bay is often represented in a wind tunnel with a cavity. In flight, this flow is unconfined, though in experiments, the cavity is surrounded by wind tunnel walls. If untreated, wind tunnel wall effects can lead to significant distortions of cavity acoustics in subsonic flows. To understand and mitigate these cavity–tunnel interactions, a parametric approach was taken for flow over an L/D = 7 cavity at Mach numbers 0.6–0.8. With solid tunnel walls, a dominant cavity tone was observed, likely due to an interaction with a tunnel duct mode. Furthermore, anmore » acoustic liner opposite the cavity decreased the amplitude of the dominant mode and its harmonics, a result observed by previous researchers. Acoustic dampeners were also placed in the tunnel sidewalls, which further decreased the dominant mode amplitudes and peak amplitudes associated with nonlinear interactions between cavity modes. This then indicates that cavity resonance can be altered by tunnel sidewalls and that spanwise coupling should be addressed when conducting subsonic cavity experiments. Though mechanisms for dominant modes and nonlinear interactions likely exist in unconfined cavity flows, these effects can be amplified by the wind tunnel walls.« less

  4. Mitigation of wind tunnel wall interactions in subsonic cavity flows

    SciTech Connect

    Wagner, Justin L.; Casper, Katya Marie; Beresh, Steven J.; Henfling, John F.; Spillers, Russell Wayne; Pruett, Brian Owen Matthew

    2015-03-06

    In this study, the flow over an open aircraft bay is often represented in a wind tunnel with a cavity. In flight, this flow is unconfined, though in experiments, the cavity is surrounded by wind tunnel walls. If untreated, wind tunnel wall effects can lead to significant distortions of cavity acoustics in subsonic flows. To understand and mitigate these cavity–tunnel interactions, a parametric approach was taken for flow over an L/D = 7 cavity at Mach numbers 0.6–0.8. With solid tunnel walls, a dominant cavity tone was observed, likely due to an interaction with a tunnel duct mode. Furthermore, an acoustic liner opposite the cavity decreased the amplitude of the dominant mode and its harmonics, a result observed by previous researchers. Acoustic dampeners were also placed in the tunnel sidewalls, which further decreased the dominant mode amplitudes and peak amplitudes associated with nonlinear interactions between cavity modes. This then indicates that cavity resonance can be altered by tunnel sidewalls and that spanwise coupling should be addressed when conducting subsonic cavity experiments. Though mechanisms for dominant modes and nonlinear interactions likely exist in unconfined cavity flows, these effects can be amplified by the wind tunnel walls.

  5. Review of Potential Wind Tunnel Balance Technologies

    NASA Technical Reports Server (NTRS)

    Burns, Devin E.; Williams, Quincy L.; Phillips, Ben D.; Commo, Sean A.; Ponder, Jonathon D.

    2016-01-01

    This manuscript reviews design, manufacture, materials, sensors, and data acquisition technologies that may benefit wind tunnel balances for the aerospace research community. Current state-of-the-art practices are used as the benchmark to consider advancements driven by researcher and facility needs. Additive manufacturing is highlighted as a promising alternative technology to conventional fabrication and has the potential to reduce both the cost and time required to manufacture force balances. Material alternatives to maraging steels are reviewed. Sensor technologies including piezoresistive, piezoelectric, surface acoustic wave, and fiber optic are compared to traditional foil based gages to highlight unique opportunities and shared challenges for implementation in wind tunnel environments. Finally, data acquisition systems that could be integrated into force balances are highlighted as a way to simplify the user experience and improve data quality. In summary, a rank ordering is provided to support strategic investment in exploring the technologies reviewed in this manuscript.

  6. The Unitary Plan Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Wedgworth, Kevin; Woo, Alex C.

    1994-01-01

    The Unitary Plan Facility is the most heavily used wind tunnel in all of NASA. Every major commercial transport and almost every fighter built in the United States over the last 30 years has been tested in this tunnel. Also tested in this tunnel complex were models of the Space Shuttle, as well as the Mercury, Gemini, and Apollo capsules. The wind tunnel represents a unique national asset of vital importance to the nation's defense and its competitive position in the world aerospace market. In 1985, the Unitary Plan Facility was named a National Historic Landmark by the National Park Service because of 'its significant associations with the development of the American Space Program.'

  7. 5-foot Vertical Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1932-01-01

    The researcher is sitting above the exit cone of the 5-foot Vertical Wind Tunnel and is examining the new 6-component spinning balance. This balance was developed between 1930 and 1933. It was an important advance in the technology of rotating or rolling balances. As M.J. Bamber and C.H. Zimmerman wrote in NACA TR 456: 'Data upon the aerodynamic characteristics of a spinning airplane may be obtained in several ways; namely, flight tests with full-scale airplanes, flight tests with balanced models, strip-method analysis of wind-tunnel force and moment tests, and wind-tunnel tests of rotating models.' Further, they note: 'Rolling-balance data have been of limited value because it has not been possible to measure all six force and moment components or to reproduce a true spinning condition. The spinning balance used in this investigation is a 6-component rotating balance from which it is possible to obtain wind-tunnel data for any of a wide range of possible spinning conditions.' Bamber and Zimmerman described the balance as follows: 'The spinning balance consists of a balance head that supports the model and contains the force-measuring units, a horizontal turntable supported by streamline struts in the center of the jet and, outside the tunnel, a direct-current driving motor, a liquid tachometer, an air compressor, a mercury manometer, a pair of indicating lamps, and the necessary controls. The balance head is mounted on the turntable and it may be set to give any radius of spin between 0 and 8 inches.' In an earlier report, NACA TR 387, Carl Wenzinger and Thomas Harris supply this description of the tunnel: 'The vertical open-throat wind tunnel of the National Advisory Committee for Aeronautics ... was built mainly for studying the spinning characteristics of airplane models, but may be used as well for the usual types of wind-tunnel tests. A special spinning balance is being developed to measure the desired forces and moments with the model simulating the actual

  8. National Wind Tunnel Complex (NWTC)

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The National Wind Tunnel Complex (NWTC) Final Report summarizes the work carried out by a unique Government/Industry partnership during the period of June 1994 through May 1996. The objective of this partnership was to plan, design, build and activate 'world class' wind tunnel facilities for the development of future-generation commercial and military aircraft. The basis of this effort was a set of performance goals defined by the National Facilities Study (NFS) Task Group on Aeronautical Research and Development Facilities which established two critical measures of improved wind tunnel performance; namely, higher Reynolds number capability and greater productivity. Initial activities focused upon two high-performance tunnels (low-speed and transonic). This effort was later descoped to a single multipurpose tunnel. Beginning in June 1994, the NWTC Project Office defined specific performance requirements, planned site evaluation activities, performed a series of technical/cost trade studies, and completed preliminary engineering to support a proposed conceptual design. Due to budget uncertainties within the Federal government, the NWTC project office was directed to conduct an orderly closure following the Systems Design Review in March 1996. This report provides a top-level status of the project at that time. Additional details of all work performed have been archived and are available for future reference.

  9. Videometric Applications in Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Burner, A. W.; Radeztsky, R. H.; Liu, Tian-Shu

    1997-01-01

    Videometric measurements in wind tunnels can be very challenging due to the limited optical access, model dynamics, optical path variability during testing, large range of temperature and pressure, hostile environment, and the requirements for high productivity and large amounts of data on a daily basis. Other complications for wind tunnel testing include the model support mechanism and stringent surface finish requirements for the models in order to maintain aerodynamic fidelity. For these reasons nontraditional photogrammetric techniques and procedures sometimes must be employed. In this paper several such applications are discussed for wind tunnels which include test conditions with Mach number from low speed to hypersonic, pressures from less than an atmosphere to nearly seven atmospheres, and temperatures from cryogenic to above room temperature. Several of the wind tunnel facilities are continuous flow while one is a short duration blowdown facility. Videometric techniques and calibration procedures developed to measure angle of attack, the change in wing twist and bending induced by aerodynamic load, and the effects of varying model injection rates are described. Some advantages and disadvantages of these techniques are given and comparisons are made with non-optical and more traditional video photogrammetric techniques.

  10. SCALING: Wind Tunnel to Flight

    NASA Astrophysics Data System (ADS)

    Bushnell, Dennis M.

    2006-01-01

    Wind tunnels have wide-ranging functionality, including many applications beyond aeronautics, and historically have been the major source of information for technological aerodynamics/aeronautical applications. There are a myriad of scaling issues/differences from flight to wind tunnel, and their study and impacts are uneven and a function of the particular type of extant flow phenomena. Typically, the most serious discrepancies are associated with flow separation. The tremendous ongoing increases in numerical simulation capability are changing and in many aspects have changed the function of the wind tunnel from a (scaled) "predictor" to a source of computational calibration/validation information with the computation then utilized as the flight prediction/scaling tool. Numerical simulations can increasingly include the influences of the various scaling issues. This wind tunnel role change has been occurring for decades as computational capability improves in all aspects. Additional issues driving this trend are the increasing cost (and time) disparity between physical experiments and computations, and increasingly stringent accuracy requirements.

  11. Other cryogenic wind tunnel projects

    NASA Technical Reports Server (NTRS)

    Kilgore, Robert A.

    1989-01-01

    The first cryogenic tunnel was built in 1972. Since then, many cryogenic wind-tunnel projects were started at aeronautical research centers around the world. Some of the more significant of these projects are described which are not covered by other lecturers at this Special Course. Described are cryogenic wind-tunnel projects in five countries: China (Chinese Aeronautical Research and Development Center); England (College of Aeronautics at Cranfield, and Royal Aerospace Establishment-Bedford); Japan (National Aerospace Laboratory, University of Tsukuba, and National Defense Academy); United States (Douglas Aircraft Co., University of Illinois at Urbana-Champaign and NASA Langley); and U.S.S.R. (Central Aero-Hydronamics Institute (TsAGI), Institute of Theoretical and Applied Mechanics (ITAM), and Physical-Mechanical Institute at Kharkov (PMI-K).

  12. The self streamlining wind tunnel. [wind tunnel walls

    NASA Technical Reports Server (NTRS)

    Goodyer, M. J.

    1975-01-01

    A two dimensional test section in a low speed wind tunnel capable of producing flow conditions free from wall interference is presented. Flexible top and bottom walls, and rigid sidewalls from which models were mounted spanning the tunnel are shown. All walls were unperforated, and the flexible walls were positioned by screw jacks. To eliminate wall interference, the wind tunnel itself supplied the information required in the streamlining process, when run with the model present. Measurements taken at the flexible walls were used by the tunnels computer check wall contours. Suitable adjustments based on streamlining criteria were then suggested by the computer. The streamlining criterion adopted when generating infinite flowfield conditions was a matching of static pressures in the test section at a wall with pressures computed for an imaginary inviscid flowfield passing over the outside of the same wall. Aerodynamic data taken on a cylindrical model operating under high blockage conditions are presented to illustrate the operation of the tunnel in its various modes.

  13. Evaluation of the in-flight noise signature of a 32-chute suppressor nozzle: Acoustic data report. [outdoor static and 40 x 80 ft. wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Moore, M. T.; Doyle, V. L.

    1977-01-01

    Outdoor static and 40 x 80 FT wind tunnel tests of the J79-15 engine/nacelle system with the conic nozzle and 32-chute exhaust suppressor were conducted to acquire the data necessary to evaluate the simulated in-flight signature of an engine-size 32-chute exhaust nozzle suppressor using the 40 x 80 ft wind tunnel and to study possible engine core noise contamination of the jet signature. The tests are described and and a sampling of the data acquired is presented. Included are aero performance summaries, as-measured and composite 1/3 OBSPL spectra for the 70 ft sideline high and low mics from the outdoor static tests, sideline traverse spectra and internal noise measurements from both the outdoor static and the 40 x 80 ft wind tunnel tests.

  14. Modifications to the 4x7 meter tunnel for acoustic research: Engineering feasibility study

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The NASA-Langley Research Center 4 x 7 Meter Low Speed Wind Tunnel is currently being used for low speed aerodynamics, V/STOL aerodynamics and, to a limited extent, rotorcraft noise research. The deficiencies of this wind tunnel for both aerodynamics and aeroacoustics research have been recognized for some time. Modifications to the wind tunnel are being made to improve the test section flow quality and to update the model cart systems. A further modification of the 4 x 7 Meter Wind Tunnel to permit rotorcraft model acoustics research has been proposed. As a precursor to the design of the proposed modifications, NASA is conducted both in-house and contracted studies to define the acoustic environment within the wind tunnel and to provide recommendations or the reduction of the wind tunnel background noise to a level acceptable to acoustics researchers. One of these studies by an acoustics consultant, has produced the primary reference documents that define the wind tunnel noise sources and outline recommended solutions.

  15. Comparison of field and wind tunnel Darrieus wind turbine data

    SciTech Connect

    Sheldahl, R.E.

    1981-01-01

    A 2-m-dia Darrieus Vertical Axis Wind Turbine with NACA-0012 blades was extensively tested in the Vought Corporation Low Speed Wind Tunnel. This same turbine was installed in the field at the Sandia National Laboratories Wind Turbine Test Site and operated to determine if field data corresponded to data obtained in the wind tunnel. It is believed that the accuracy of the wind tunnel test data was verified and thus the credibility of that data base was further established.

  16. Research at NASA's NFAC wind tunnels

    NASA Technical Reports Server (NTRS)

    Edenborough, H. Kipling

    1990-01-01

    The National Full-Scale Aerodynamics Complex (NFAC) is a unique combination of wind tunnels that allow the testing of aerodynamic and dynamic models at full or large scale. It can even accommodate actual aircraft with their engines running. Maintaining full-scale Reynolds numbers and testing with surface irregularities, protuberances, and control surface gaps that either closely match the full-scale or indeed are those of the full-scale aircraft help produce test data that accurately predict what can be expected from future flight investigations. This complex has grown from the venerable 40- by 80-ft wind tunnel that has served for over 40 years helping researchers obtain data to better understand the aerodynamics of a wide range of aircraft from helicopters to the space shuttle. A recent modification to the tunnel expanded its maximum speed capabilities, added a new 80- by 120-ft test section and provided extensive acoustic treatment. The modification is certain to make the NFAC an even more useful facility for NASA's ongoing research activities. A brief background is presented on the original facility and the kind of testing that has been accomplished using it through the years. A summary of the modification project and the measured capabilities of the two test sections is followed by a review of recent testing activities and of research projected for the future.

  17. Wind turbine acoustics research bibliography with selected annotation

    NASA Technical Reports Server (NTRS)

    Hubbard, Harvey H.; Shepherd, Kevin P.

    1988-01-01

    Citations of documents are included, which represent the state-of-the-art of technology in each of the following acoustics subject areas: Prediction of Wind Turbine Noise; Acoustic Measurements for Wind Tunnels; Effect of Wind Turbine Noise on Building Structures, People and Communities; Atmospheric Propagation; and Measurement Technology Including Wind Screens. Documents are listed in chronological order in each section of the paper, with key documents and associated annotation listed first. The sources are given along with acquisition numbers, when available, to expedite the acquisition of copies of the documents.

  18. Wind tunnel flow generation section

    NASA Technical Reports Server (NTRS)

    Sorensen, N. E. (Inventor)

    1974-01-01

    A flow generation section for a wind tunnel test facility is described which provides a uniform flow for the wind tunnel test section over a range of different flow velocities. The throat of the flow generation section includes a pair of opposed boundary walls which are porous to the flowing medium in order to provide an increase of velocity by expansion. A plenum chamber is associated with the exterior side of each of such porous walls to separate the same from ambient pressure. A suction manifold is connected by suction lines with each one of the chambers. Valves are positioned in each of the lines to enable the suction manifold to be independently varied.

  19. The optimum hypersonic wind tunnel

    NASA Technical Reports Server (NTRS)

    Trimmer, L. L.; Cary, A., Jr.; Voisinet, R. L. P.

    1986-01-01

    The capabilities of existing hypersonic wind tunnels in the U.S. are assessed to form a basis for recommendations for a new, costly facility which would provide data for modeling the hypervelocity aerodynamics envisioned for the new generation of aerospace vehicles now undergoing early studies. Attention is given to the regimes, both entry and aerodynamic, which the new vehicles will encounter, and the shortcomings of data generated for the Orbiter before flight are discussed. The features of foreign-gas, impulse, aeroballistic range, arc-heated and combustion-heated facilities are examined, noting that in any hypersonic wind tunnel the flow must be preheated to prevent liquefaction upon expansion in the test channel. The limitations of the existing facilities and the identification of the regimes which must be studied lead to a description of the characteristics of an optimum hypersonic wind tunnel, including the operations and productivity, the instrumentation, the nozzle design and the flow quality. Three different design approaches are described, each costing at least $100 million to achieve workability.

  20. Noise measurement in wind tunnels, workshop summary

    NASA Technical Reports Server (NTRS)

    Hickley, D. H.; Williams, J.

    1982-01-01

    In reviewing the progress made in acoustic measurements in wind tunnels over the 5-yr span of the workshops, it is evident that a great deal of progress has occurred. Specialized facilities are now on line, special measurement techniques were developed, and corrections were devised and proven. This capability is in the process of creating a new and more correct data bank on acoustic phenomena, and represents a major step forward in acoustics technology. Additional work is still required, but now, rather than concentrating on facilities and techniques, researchers may more profitably concentrate on noise-source modeling, with the simulation of propulsor noise source (in flight) and of propulsor/airframe airflow characteristics. Promising developments in directional acoustic receivers and other discrimination/correlation techniques should now be regularly exploited, in part for model noise-source diagnosis, but also to expedite extraction of the lone source signal from any residual background noise and reverberation in the working chamber and from parasitic noise due to essential rigs or instrumentation inside the airstream.

  1. RITD – Wind tunnel testing

    NASA Astrophysics Data System (ADS)

    Haukka, Harri; Harri, Ari-Matti; Aleksashkin, Sergei; Koryanov, Valeri; Schmidt, Walter; Heilimo, Jyri; Finchenko, Valeri; Martynov, Maxim; Ponomarenko, Andrey; Kazakovtsev, Victor; Arruego, Ignazio

    2015-04-01

    An atmospheric re-entry and descent and landing system (EDLS) concept based on inflatable hypersonic decelerator techniques is highly promising for the Earth re-entry missions. We developed such EDLS for the Earth re-entry utilizing a concept that was originally developed for Mars. This EU-funded project is called RITD - Re-entry: Inflatable Technology Development - and it was to assess the bene¬fits of this technology when deploying small payloads from low Earth orbits to the surface of the Earth with modest costs. The principal goal was to assess and develope a preliminary EDLS design for the entire relevant range of aerodynamic regimes expected to be encountered in Earth's atmosphere during entry, descent and landing. The RITD entry and descent system utilizes an inflatable hypersonic decelerator. Development of such system requires a combination of wind tunnel tests and numerical simulations. This included wind tunnel tests both in transsonic and subsonic regimes. The principal aim of the wind tunnel tests was the determination of the RITD damping factors in the Earth atmosphere and recalculation of the results for the case of the vehicle descent in the Mars atmosphere. The RITD mock-up model used in the tests was in scale of 1:15 of the real-size vehicle as the dimensions were (midsection) diameter of 74.2 mm and length of 42 mm. For wind tunnel testing purposes the frontal part of the mock-up model body was manufactured by using a PolyJet 3D printing technology based on the light curing of liquid resin. The tail part of the mock-up model body was manufactured of M1 grade copper. The structure of the mock-up model placed th center of gravity in the same position as that of the real-size RITD. The wind tunnel test program included the defining of the damping factor at seven values of Mach numbers 0.85; 0.95; 1.10; 1.20; 1.25; 1.30 and 1.55 with the angle of attack ranging from 0 degree to 40 degrees with the step of 5 degrees. The damping characteristics of

  2. Evaluation of the Acoustic Measurement Capability of the NASA Langley V/STOL Wind Tunnel Open Test Section with Acoustically Absorbent Ceiling and Floor Treatments

    NASA Technical Reports Server (NTRS)

    Theobald, M. A.

    1978-01-01

    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.

  3. Quiet Supersonic Wind Tunnel Development

    NASA Technical Reports Server (NTRS)

    King, Lyndell S.; Kutler, Paul (Technical Monitor)

    1994-01-01

    The ability to control the extent of laminar flow on swept wings at supersonic speeds may be a critical element in developing the enabling technology for a High Speed Civil Transport (HSCT). Laminar boundary layers are less resistive to forward flight than their turbulent counterparts, thus the farther downstream that transition from laminar to turbulent flow in the wing boundary layer is extended can be of significant economic impact. Due to the complex processes involved experimental studies of boundary layer stability and transition are needed, and these are performed in "quiet" wind tunnels capable of simulating the low-disturbance environment of free flight. At Ames, a wind tunnel has been built to operate at flow conditions which match those of the HSCT laminar flow flight demonstration 'aircraft, the F-16XL, i.e. at a Mach number of 1.6 and a Reynolds number range of 1 to 3 million per foot. This will allow detailed studies of the attachment line and crossflow on the leading edge area of the highly swept wing. Also, use of suction as a means of control of transition due to crossflow and attachment line instabilities can be studied. Topics covered include: test operating conditions required; design requirements to efficiently make use of the existing infrastructure; development of an injector drive system using a small pilot facility; plenum chamber design; use of computational tools for tunnel and model design; and early operational results.

  4. Wind tunnel investigation on wind turbine wakes and wind farms

    NASA Astrophysics Data System (ADS)

    Iungo, G. V.; Coëffé, J.; Porté-Agel, F.

    2012-04-01

    The interaction between atmospheric boundary layer and wind farms leads to flow modifications, which need to be deeply characterized in order to relate them to wind farm performance. The wake flow produced from a wind farm is the result of a strong interaction between multiple turbine wakes, so that the wind farm configuration turns out to be one of the dominant features to enhance power production. For the present work a wind tunnel investigation was carried out with hot-wire anemometry and velocity measurements performed with multi-hole pressure probes. The tested wind farms consist of miniature three-bladed wind turbine models. Preliminarily, the wake flow generated from a single wind turbine is surveyed, which is characterized by a strong velocity defect lying in proximity of the wind turbine hub height. The wake gradually recovers by moving downstream; the characteristics of the incoming boundary layer and wind turbulence intensity can strongly affect the wake recovery, and thus performance of following wind turbines. An increased turbulence level is typically detected downstream of each wind turbine for heights comparable to the wind turbine blade top-tip. These wake flow fluctuations produce increased fatigue loads on the following wind turbines within a wind farm, which could represent a significant hazard for real wind turbines. Dynamics of vorticity structures present in wind turbine wakes are also investigated; particular attention is paid to the downstream evolution of the tip helicoidal vortices and to oscillations of the hub vortex. The effect of wind farm layout on power production is deeply investigated. Particular emphasis is placed on studying how the flow adjusts as it moves inside the wind farm and can affect the power production. Aligned and staggered wind farm configurations are analysed, also with varying separation distances in the streamwise and spanwise directions. The present experimental results are being used to test and guide the

  5. Wind Turbine Acoustics

    NASA Technical Reports Server (NTRS)

    Hubbard, Harvey H.; Shepherd, Kevin P.

    2009-01-01

    Wind turbine generators, ranging in size from a few kilowatts to several megawatts, are producing electricity both singly and in wind power stations that encompass hundreds of machines. Many installations are in uninhabited areas far from established residences, and therefore there are no apparent environmental impacts in terms of noise. There is, however, the potential for situations in which the radiated noise can be heard by residents of adjacent neighborhoods, particularly those neighborhoods with low ambient noise levels. A widely publicized incident of this nature occurred with the operation of the experimental Mod-1 2-MW wind turbine, which is described in detail elsewhere. Pioneering studies which were conducted at the Mod-1 site on the causes and remedies of noise from wind turbines form the foundation of much of the technology described in this chapter.

  6. The Beginner's Guide to Wind Tunnels with TunnelSim and TunnelSys

    NASA Technical Reports Server (NTRS)

    Benson, Thomas J.; Galica, Carol A.; Vila, Anthony J.

    2010-01-01

    The Beginner's Guide to Wind Tunnels is a Web-based, on-line textbook that explains and demonstrates the history, physics, and mathematics involved with wind tunnels and wind tunnel testing. The Web site contains several interactive computer programs to demonstrate scientific principles. TunnelSim is an interactive, educational computer program that demonstrates basic wind tunnel design and operation. TunnelSim is a Java (Sun Microsystems Inc.) applet that solves the continuity and Bernoulli equations to determine the velocity and pressure throughout a tunnel design. TunnelSys is a group of Java applications that mimic wind tunnel testing techniques. Using TunnelSys, a team of students designs, tests, and post-processes the data for a virtual, low speed, and aircraft wing.

  7. Aspects of investigating STOL noise using large-scale wind-tunnel models.

    NASA Technical Reports Server (NTRS)

    Falarski, M. D.; Soderman, P. T.; Koenig, D. G.

    1973-01-01

    The applicability of the NASA Ames 40- by 80-foot wind tunnel for acoustic research on STOL concepts has been investigated. The acoustic characteristics of the wind-tunnel test section have been studied with calibrated acoustic sources. Acoustic characteristics of several large-scale STOL models have been studied in both the free-field and wind-tunnel acoustic environments. The results of these studies indicate that the acoustic characteristics of large-scale STOL models can be measured in the wind tunnel if the test section acoustic environment and model acoustic similitude are taken into consideration. The reverberant field of the test section must be determined with an acoustically similar noise source. A directional microphone, a phased array of microphones, and extrapolation of near-field data to far-field are some of the techniques being explored as possible solutions to the directivity loss in a reverberant field. The model sound pressure levels must be of sufficient magnitude to be distinguishible from the wind-tunnel background noise.

  8. SSX MHD plasma wind tunnel

    NASA Astrophysics Data System (ADS)

    Brown, Michael R.; Schaffner, David A.

    2015-06-01

    A new turbulent plasma source at the Swarthmore Spheromak Experiment (SSX) facility is described. The MHD wind tunnel configuration employs a magnetized plasma gun to inject high-beta plasma into a large, well-instrumented, vacuum drift region. This provides unique laboratory conditions approaching that in the solar wind: there is no applied background magnetic field in the drift region and has no net axial magnetic flux; the plasma flow speed is on the order of the local sound speed (M ~ 1), so flow energy density is comparable to thermal energy density; and the ratio of thermal to magnetic pressure is of order unity (plasma β ~ 1) so thermal energy density is also comparable to magnetic energy density. Results presented here and referenced within demonstrate the new capabilities and show how the new platform is proving useful for fundamental plasma turbulence studies.

  9. Wind tunnel simulations of aerolian processes

    NASA Technical Reports Server (NTRS)

    Greeley, R.

    1984-01-01

    The characteristics of aerolian (wind) activity as a surface modifying process on Earth, Mars, Venus, and appropriate satellites was determined. A combination of spacecraft data analysis, wind tunnel simulations, and terrestrial field analog studies were used to determine these characteristics. Wind tunnel experiments simulating Venusian surface conditions demonstrate that rolling of particles may be an important mode of transport by winds on Venus and that aerolian processes in the dense atmosphere may share attributes of both aerolian and aqueous environments on Earth.

  10. Models for cryogenic wind tunnels

    NASA Technical Reports Server (NTRS)

    Lawing, Pierce L.

    1989-01-01

    Model requirements, types of model construction methods, and research in new ways to build models are discussed. The 0.3-m Transonic Cryogenic Tunnel was in operation for 16 years and many 2-D airfoil pressure models were tested. In addition there were airfoil models dedicated to transition detection techniques and other specialized research. There were also a number of small 3-D models tested. A chronological development in model building technique is described which led to the construction of many successful models. The difficulties of construction are illustrated by discussing several unsuccessful model fabrication attempts. The National Transonic Facility, a newer and much larger tunnel, was used to test a variety of models including a submarine, transport and fighter configurations, and the Shuttle Orbiter. A new method of building pressure models was developed and is described. The method is centered on the concept of bonding together plates with pressure channels etched into the bond planes, which provides high density pressure instrumentation with minimum demand on parent model material. With care in the choice of materials and technique, vacuum brazing can be used to produce strong bonds without blocking pressure channels and with no bonding voids between channels. Using multiple plates, a 5 percent wing with 96 orifices was constructed and tested in a transonic cryogenic wind tunnel. Samples of test data are presented and future applications of the technology are suggested.

  11. Reducing Airborne Debris In Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Sleeper, Robert K.

    1993-01-01

    In proposed technique to trap airborne particles during normal wind-tunnel testing, large sections of single-backed adhesive paper or cloth mounted with adhesive side exposed to flow. Adhesive material securely installed on flow vanes, walls, or other surfaces of wind tunnel in manner facilitating replacement. Installed or replaced anytime permissible to enter tunnel. Provides safe, inexpensive, rugged, passive, continuous, and otherwise inert cleansing action suitable for wind tunnel of any size. Also applied to specialized clean-room environments and to air-conditioning systems in general.

  12. Acoustic treatment of the NASA Langley 4- by 7-meter tunnel: A feasibility study

    NASA Technical Reports Server (NTRS)

    Yu, J. C.; Abrahamson, A. L.

    1986-01-01

    A feasibility study for upgrading the NASA Langley 4- by 7-Meter Tunnel so that it may be used for aeroacoustic research related to helicopters is described. The requirements for noise research leading to the design of the next generation of helicopters impose a set of acoustic test criteria that no existing wind tunnel in the United States can presently meet. Included in this feasibility study are the following considerations: (1) an evaluation of general wind-tunnel requirements and desired tunnel background noise levels for helicopter aeroacoustic research; (2) an assessment of the present acoustic environment for testing model rotors; (3) a diagnostic investigation of tunnel background noise sources and paths; (4) acoustic treatment options for tunnel background noise reduction and a trade-off study between these options; (5) an engineering feasibility assessment of the selected option; and (6) an integrated analysis of study components and recommendations of treatment for an approach to meet the tunnel background noise reduction goal. It is concluded that the Langley 4- by 7-Meter Tunnel is a fundamentally suitable facility for helicopter aeroacoustic research. It is also concluded that acoustic treatment of this facility for meeting the required tunnel background noise goal can be accomplished technically at reasonable risk and cost.

  13. Comparison of wind tunnel and flyover noise measurements of the YOV-10A STOL aircraft

    NASA Technical Reports Server (NTRS)

    Atencio, A., Jr.; Soderman, P. T.

    1972-01-01

    The YOV-10A Research Aircraft was flown to obtain flyover noise data that could be compared to noise data measured in the 40- by 80- foot wind tunnel at NASA Ames Research Center. The flyover noise measurements were made during the early morning hours on runway 32L at Moffett Field, California. A number of passes were made at 50 ft altitude in level flight with an airplane configuration closely matching that tested in the wind tunnel. Two passes were selected as prime and were designated for full data reduction. The YOV-10A was flown over a microphone field geometrically similar to the microphone array set up in the wind tunnel. An acoustic center was chosen as a matching point for the data. Data from the wind tunnel and flyover were reduced and appropiate corrections were applied to compare the data. Results show that wind tunnel and flight test acoustic data agreed closely.

  14. WT - WIND TUNNEL PERFORMANCE ANALYSIS

    NASA Technical Reports Server (NTRS)

    Viterna, L. A.

    1994-01-01

    WT was developed to calculate fan rotor power requirements and output thrust for a closed loop wind tunnel. The program uses blade element theory to calculate aerodynamic forces along the blade using airfoil lift and drag characteristics at an appropriate blade aspect ratio. A tip loss model is also used which reduces the lift coefficient to zero for the outer three percent of the blade radius. The application of momentum theory is not used to determine the axial velocity at the rotor plane. Unlike a propeller, the wind tunnel rotor is prevented from producing an increase in velocity in the slipstream. Instead, velocities at the rotor plane are used as input. Other input for WT includes rotational speed, rotor geometry, and airfoil characteristics. Inputs for rotor blade geometry include blade radius, hub radius, number of blades, and pitch angle. Airfoil aerodynamic inputs include angle at zero lift coefficient, positive stall angle, drag coefficient at zero lift coefficient, and drag coefficient at stall. WT is written in APL2 using IBM's APL2 interpreter for IBM PC series and compatible computers running MS-DOS. WT requires a CGA or better color monitor for display. It also requires 640K of RAM and MS-DOS v3.1 or later for execution. Both an MS-DOS executable and the source code are provided on the distribution medium. The standard distribution medium for WT is a 5.25 inch 360K MS-DOS format diskette in PKZIP format. The utility to unarchive the files, PKUNZIP, is also included. WT was developed in 1991. APL2 and IBM PC are registered trademarks of International Business Machines Corporation. MS-DOS is a registered trademark of Microsoft Corporation. PKUNZIP is a registered trademark of PKWare, Inc.

  15. Rudolf Hermann, wind tunnels and aerodynamics

    NASA Astrophysics Data System (ADS)

    Lundquist, Charles A.; Coleman, Anne M.

    2008-04-01

    Rudolf Hermann was born on December 15, 1904 in Leipzig, Germany. He studied at the University of Leipzig and at the Aachen Institute of Technology. His involvement with wind tunnels began in 1934 when Professor Carl Wieselsberger engaged him to work at Aachen on the development of a supersonic wind tunnel. On January 6, 1936, Dr. Wernher von Braun visited Dr. Hermann to arrange for use of the Aachen supersonic wind tunnel for Army problems. On April 1, 1937, Dr. Hermann became Director of the Supersonic Wind Tunnel at the Army installation at Peenemunde. Results from the Aachen and Peenemunde wind tunnels were crucial in achieving aerodynamic stability for the A-4 rocket, later designated as the V-2. Plans to build a Mach 10 'hypersonic' wind tunnel facility at Kochel were accelerated after the Allied air raid on Peenemunde on August 17, 1943. Dr. Hermann was director of the new facility. Ignoring destruction orders from Hitler as WWII approached an end in Europe, Dr. Hermann and his associates hid documents and preserved wind tunnel components that were acquired by the advancing American forces. Dr. Hermann became a consultant to the Air Force at its Wright Field in November 1945. In 1951, he was named professor of Aeronautical Engineering at the University of Minnesota. In 1962, Dr. Hermann became the first Director of the Research Institute at the University of Alabama in Huntsville (UAH), a position he held until he retired in 1970.

  16. Limitations on wind-tunnel pressure signature extrapolation

    NASA Technical Reports Server (NTRS)

    Mack, Robert J.; Darden, Christine M.

    1992-01-01

    Analysis of some recent experimental sonic boom data has revived the hypothesis that there is a closeness limit to the near-field separation distance from which measured wind tunnel pressure signatures can be extrapolated to the ground as though generated by a supersonic-cruise aircraft. Geometric acoustic theory is used to derive an estimate of this distance and the sample data is used to provide a preliminary indication of practical separation distance values.

  17. Full-Scale Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Construction of Full-Scale Tunnel (FST) balance. Smith DeFrance described the 6-component type balance in NACA TR No. 459 (which also includes a schematic diagram of the balance and its various parts). 'Ball and socket fittings at the top of each of the struts hod the axles of the airplane to be tested; the tail is attached to the triangular frame. These struts are secured to the turntable, which is attached to the floating frame. This frame rests on the struts (next to the concrete piers on all four corners), which transmit the lift forces to the scales (partially visible on the left). The drag linkage is attached to the floating frame on the center line and, working against a known counterweight, transmits the drag force to the scale (center, face out). The cross-wind force linkages are attached to the floating frame on the front and rear sides at the center line. These linkages, working against known counterweights, transmit the cross-wind force to scales (two front scales, face in). In the above manner the forces in three directions are measured and by combining the forces and the proper lever arms, the pitching, rolling, and yawing moments can be computed. The scales are of the dial type and are provided with solenoid-operated printing devices. When the proper test condition is obtained, a push-button switch is momentarily closed and the readings on all seven scales are recorded simultaneously, eliminating the possibility of personal errors.'

  18. Wind tunnel pressurization and recovery system

    NASA Technical Reports Server (NTRS)

    Pejack, Edwin R.; Meick, Joseph; Ahmad, Adnan; Lateh, Nordin; Sadeq, Omar

    1988-01-01

    The high density, low toxicity characteristics of refrigerant-12 (dichlorofluoromethane) make it an ideal gas for wind tunnel testing. Present limitations on R-12 emissions, set to slow the rate of ozone deterioration, pose a difficult problem in recovery and handling of large quantities of R-12. This preliminary design is a possible solution to the problem of R-12 handling in wind tunnel testing. The design incorporates cold temperature condensation with secondary purification of the R-12/air mixture by adsorption. Also discussed is the use of Freon-22 as a suitable refrigerant for the 12 foot wind tunnel.

  19. A wind tunnel database using RIM

    NASA Technical Reports Server (NTRS)

    Wray, W. O., Jr.

    1984-01-01

    Engineering data base development which has become increasingly widespread to industry with the availability of data management systems is examined. A large data base was developed for wind tunnel data and related model test information, using RIM as the data base manager. The arrangement of the wind tunnel data into the proper schema for the most efficient database utilization is discussed. The FORTRAN interface program of RIM is used extensively in the loading phases of the data base and by the users. Several examples to illustrate how the Wind Tunnel Data base might be searched for specific data items and test information using RIM are presented.

  20. A wind tunnel application of large-field focusing schlieren

    NASA Technical Reports Server (NTRS)

    Ponton, Michael K.; Seiner, John M.; Mitchell, L. K.; Manning, James C.; Jansen, Bernard J.; Lagen, Nicholas T.

    1992-01-01

    A large-field focusing schlieren apparatus was installed in the NASA Lewis Research Center 9 by 15 foot wind tunnel in an attempt to determine the density gradient flow field of a free jet issuing from a supersonic nozzle configuration. The nozzle exit geometry was designed to reduce acoustic emissions from the jet by enhancing plume mixing. Thus, the flow exhibited a complex three-dimensional structure which warranted utilizing the sharp focusing capability of this type of schlieren method. Design considerations concerning tunnel limitations, high-speed photography, and video tape recording are presented in the paper.

  1. Aeroelastic instability stoppers for wind tunnel models

    NASA Technical Reports Server (NTRS)

    Doggett, R. V., Jr.; Ricketts, R. H. (Inventor)

    1981-01-01

    A mechanism for diverting the flow in a wind tunnel from the wing of a tested model is described. The wing is mounted on the wall of a tunnel. A diverter plate is pivotally mounted on the tunnel wall ahead of the model. An actuator fixed to the tunnel is pivotably connected to the diverter plate, by plunger. When the model is about to become unstable during the test the actuator moves the diverter plate from the tunnel wall to divert maintaining stable model conditions. The diverter plate is then retracted to enable normal flow.

  2. Model of 5-Foot Vertical Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Model of 5-Foot Vertical Wind Tunnel. Carl Wenzinger and Thomas Harris wrote in NACA TR 387: 'The vertical open-throat wind tunnel of the National Advisory Committee for Aeronautics ... was built mainly for studying the spinning characteristics of airplane models, but may be used as well for the usual types of wind-tunnel tests. A special spinning balance is being developed to measure the desired forces and moments with the model simulating the actual spin of an airplane. Satisfactory air flow has been attained with a velocity that is uniform over the jet to within 0.5 per cent. The turbulence present in the tunnel has been compared with that of several other tunnels by means of the results of sphere drag tests and was found to average well with the values of those tunnels. Included also in the report are comparisons of results of stable autorotation and of rolling-moment tests obtained both in the vertical tunnel and in the old horizontal 5-foot atmospheric tunnel.' The design of a vertical tunnel having a 5-foot diameter jet was accordingly started by the National Advisory Committee for Aeronautics in 1928. Actual construction of the new tunnel was completed in 1930, and the calibration tests were then made.'

  3. Field verification of the wind tunnel coefficients

    NASA Technical Reports Server (NTRS)

    Gawronski, W. K.; Mellstrom, J. A.

    1994-01-01

    Accurate information about wind action on antennas is required for reliable prediction of antenna pointing errors in windy weather and for the design of an antenna controller with wind disturbance rejection properties. The wind tunnel data obtained 3 years ago using a scaled antenna model serves as an antenna industry standard, frequently used for the first purpose. The accuracy of the wind tunnel data has often been challenged, since they have not yet been tested in a field environment (full-aized antenna, real wind, actual terrain, etc.). The purpose of this investigation was to obtain selected field measurements and compare them with the available wind tunnel data. For this purpose, wind steady-state torques of the DSS-13 antenna were measured, and dimensionless wind torque coefficients were obtained for a variety of yaw and elevation angles. The results showed that the differences between the wind tunnel torque coefficients and the field torque coefficients were less than 10 percent of their values. The wind-gusting action on the antenna was characterized by the power spectra of the antenna encoder and the antenna torques. The spectra showed that wind gusting primarily affects the antenna principal modes.

  4. Forward velocity effects on fan noise and the suppression characteristics of advanced inlets as measured in the NASA Ames 40 by 80 foot wind tunnel: Acoustic data report

    NASA Technical Reports Server (NTRS)

    Moore, M. T.

    1981-01-01

    Forward velocity effects on the forward radiated fan noise and on the suppression characteristics of three advanced inlets relative to a baseline cylindrical inlet were measured in a wind tunnel. A modified JT15D turbofan engine in a quiet nacelle was the source of fan noise; the advanced inlets were a CTOL hybrid inlet, an STOL hybrid inlet, and a treated deflector inlet. Also measured were the static to flight effects on the baseline inlet noise and the effects on the fan noise of canting the baseline inlet 4 deg downward to simulate typical wing mounted turbofan engines. The 1/3 octave band noise data from these tests are given along with selected plots of 1/3 octave band spectra and directivity and full scale PNL directivities. The test facilities and data reduction techniques used are also described.

  5. Reduction of acoustic disturbances in the test section of supersonic wind tunnels by laminarizing their nozzle and test section wall boundary layers by means of suction

    NASA Technical Reports Server (NTRS)

    Pfenninger, W.; Syberg, J.

    1974-01-01

    The feasibility of quiet, suction laminarized, high Reynolds number (Re) supersonic wind tunnel nozzles was studied. According to nozzle wall boundary layer development and stability studies, relatively weak area suction can prevent amplified nozzle wall TS (Tollmien-Schlichting) boundary layer oscillations. Stronger suction is needed in and shortly upstream of the supersonic concave curvature nozzle area to avoid transition due to amplified TG (Taylor-Goertler) vortices. To control TG instability, moderately rapid and slow expansion nozzles require smaller total suction rates than rapid expansion nozzles, at the cost of larger nozzle length Re and increased TS disturbances. Test section mean flow irregularities can be minimized with suction through longitudinal or highly swept slots (swept behind local Mach cone) as well as finely perforated surfaces. Longitudinal slot suction is optimized when the suction-induced crossflow velocity increases linearly with surface distance from the slot attachment line toward the slot (through suitable slot geometry). Suction in supersonic blowdown tunnels may be operated by one or several individual vacuum spheres.

  6. AMELIA Tests in NASA Wind Tunnel

    NASA Video Gallery

    This report from "This Week @ NASA" describes recent aerodynamic tests of a subscale model of the Advanced Model for Extreme Lift and Improved Aeroacoustics, or "AMELIA," in a NASA wind tunnel. The...

  7. On a new type of wind tunnel

    NASA Technical Reports Server (NTRS)

    Munk, Max

    1921-01-01

    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.

  8. NASA Now: Engineering Design: Wind Tunnel Testing

    NASA Video Gallery

    Dr. Norman W. Schaeffler, a NASA aerospace research engineer, describes how wind tunnels work and how aircraft designers use them to understand aerodynamic forces at low speeds. Learn the advantage...

  9. Program Analyzes Performance Of A Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Viterna, L. A.

    1994-01-01

    WT computer program developed to calculate rotor power required by, and output thrust produced by, fan in closed-loop wind tunnel. Uses blade-element theory to calculate aerodynamic forces along each blade of fan. Written in APL2.

  10. Wind-Tunnel/Flight Correlation, 1981

    NASA Technical Reports Server (NTRS)

    Mckinney, L. W. (Editor); Baals, D. D. (Editor)

    1982-01-01

    Wind-tunnel/flight correlation activities are reviewed to assure maximum effectiveness of the early experimental programs of the National Transonic Facility (NTF). Topics included a status report of the NTF, the role of tunnel-to-tunnel correlation, a review of past flight correlation research and the resulting data base, the correlation potential of future flight vehicles, and an assessment of the role of computational fluid dynamics.

  11. 40 CFR Table F-2 to Subpart F of... - Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and Static Chamber Test F Table F-2 to Subpart F... Part 53—Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration...

  12. 40 CFR Table F-2 to Subpart F of... - Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 6 2012-07-01 2012-07-01 false Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and Static Chamber Test F Table F-2 to Subpart F... Part 53—Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration...

  13. 40 CFR Table F-2 to Subpart F of... - Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and Static Chamber Test F Table F-2 to Subpart F... Part 53—Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration...

  14. 40 CFR Table F-2 to Subpart F of... - Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and Static Chamber Test F Table F-2 to Subpart F... Part 53—Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration...

  15. An experimental study of the structure and acoustic field of a jet in a cross stream. [Ames 7-ft by 10-ft wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Camelier, I.; Karamcheti, K.

    1976-01-01

    The plane of symmetry of a high speed circular jet was surveyed to measure the mean and turbulent velocity fields by using constant temperature hot wire anemometry. The intensity of the noise radiated from the jet was determined in the tunnel test section by utilizing the cross-correlation at a particular time delay between the signals of two microphones suitably located along a given direction. Experimental results indicate that the turbulent intensity inside the crossflow jet increases by a factor of (1 + 1/2) as compared to the turbulent intensity of the same jet under free conditions, with r indicating the ratio of the jet velocity by the cross stream velocity. The peak observed in the turbulence spectra obtained inside the potential core of the jet has a frequency that increases by the same factor with respect to the corresponding frequency measured in the case of the free jet. The noise radiated by the jet becomes more intense as the crossflow velocity increases. The measured acoustic intensity of the crossflow jet is higher than the value which would be expected from the increase of the turbulent intensity only.

  16. Review of Aeronautical Wind Tunnel Facilities

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The nation's aeronautical wind tunnel facilities constitute a valuable technological resource and make a significant contribution to the global supremacy of U.S. aircraft, both civil and military. At the request of NASA, the National Research Council's Aeronautics and Space Engineering Board organized a commitee to review the state of repair, adequacy, and future needs of major aeronautical wind tunnel facilities in meeting national goals. The comittee identified three main areas where actions are needed to sustain the capability of NASA's aeronautical wind tunnel facilities to support the national aeronautical research and development activities: tunnel maintenance and upgrading, productivity enhancement, and accommodation of new requirements (particularly in hypersonics). Each of these areas are addressed and the committee recommendations for appropriate actions presented.

  17. Active Control of Wind Tunnel Noise

    NASA Technical Reports Server (NTRS)

    Hollis, Patrick (Principal Investigator)

    1991-01-01

    The need for an adaptive active control system was realized, since a wind tunnel is subjected to variations in air velocity, temperature, air turbulence, and some other factors such as nonlinearity. Among many adaptive algorithms, the Least Mean Squares (LMS) algorithm, which is the simplest one, has been used in an Active Noise Control (ANC) system by some researchers. However, Eriksson's results, Eriksson (1985), showed instability in the ANC system with an ER filter for random noise input. The Restricted Least Squares (RLS) algorithm, although computationally more complex than the LMS algorithm, has better convergence and stability properties. The ANC system in the present work was simulated by using an FIR filter with an RLS algorithm for different inputs and for a number of plant models. Simulation results for the ANC system with acoustic feedback showed better robustness when used with the RLS algorithm than with the LMS algorithm for all types of inputs. Overall attenuation in the frequency domain was better in the case of the RLS adaptive algorithm. Simulation results with a more realistic plant model and an RLS adaptive algorithm showed a slower convergence rate than the case with an acoustic plant as a delay plant. However, the attenuation properties were satisfactory for the simulated system with the modified plant. The effect of filter length on the rate of convergence and attenuation was studied. It was found that the rate of convergence decreases with increase in filter length, whereas the attenuation increases with increase in filter length. The final design of the ANC system was simulated and found to have a reasonable convergence rate and good attenuation properties for an input containing discrete frequencies and random noise.

  18. Design, fabrication, and characterization of an anechoic wind tunnel facility

    NASA Astrophysics Data System (ADS)

    Mathew, Jose

    The design, fabrication, and characterization of an anechoic wind tunnel facility at the University of Florida are presented. The objective of this research is to develop and rigorously characterize an anechoic wind tunnel suitable for detailed aerodynamic and aeroacoustic research. A complete tunnel design methodology is developed to optimize the design of the individual components of the wind tunnel circuit, and modern analysis tools, such as computational fluid dynamics and structural finite element analyses, are used to validate the design. The wind tunnel design is an "L-shaped"open circuit with an open jet test section driven by a 300 HP centrifugal fan. Airflow enters the wind tunnel through a settling duct with a honeycomb section and a set of four screens. An optimized, minimum length (3.05 m) 8:1 contraction accelerates the flow into a rectangular test section that measures 0.74 m by 1.12 m by 1.83 m. Mach number similarity dictates the maximum velocity attainable in the test section to be 76 m/s; thus the maximum Reynolds number based on chord (chord=2/3 span) attainable is in the 3-4 million range. The flow leaving the test section enters an acoustically treated and 2D diffuser that simultaneously provides static pressure recovery and attenuates fan noise. The flow then turns a 90° corner with turning vanes and enters a second diffuser. The flow leaving the second diffuser enters the fan through a transition section. The wind tunnel was characterized rigorously at speeds up to 43 m/s to ensure the quality of the future aerodynamic and aeroacoustic measurements. The overall SPL from 100 Hz--20 kHz ranges from 54.8 dB at 18 m/s to 75.7 dB at 43 m/s. The freestream turbulence level has a value of 0.035%, and the flow non uniformity in the test section was found to be < 0.7% for a test section speed of 17 m/s. The outcome of this work is an anechoic wind tunnel with excellent flow quality, low background noise, and the largest Reynolds number capability

  19. Experimental study of acoustic loads on an upper-surface-blown STOL airplane configuration. [Langley full-scale wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Willis, C. M.; Schoenster, J. A.

    1979-01-01

    Fluctuating pressure levels were measured on the flap and fuselage of an upper-surface-blown jet-flap airplane configuration in a wind tunnel. The model tested had turbofan engines with a bypass ratio of 3 and a thrust rating of 10 kN. Rectangular nozzles were mounted flush with the upper surface at 35 percent of the wing chord. Test parameters were flap deflection angle, jet impingement angle, angle of attack, free-stream velocity, spanwise location of the engine, and jet dynamic pressure. Load levels were high throughout the jet impingement region, with the highest levels (about 159 dB) occurring on the fuselage and near the knee of the flap. The magnitude of the forward-velocity effect appeared to depend upon the ratio of free-stream and jet velocities. Good agreement was obtained between fluctuating pressure spectra measured at jet dynamic pressures of 7 and 22 kPa when the spectra were scaled by nondimensional functions of dynamic pressure, velocity, and the empirical relationship between dynamic pressure and overall fluctuating pressure level.

  20. Viscous effects on the resonance of a slotted wind tunnel using finite elements

    NASA Technical Reports Server (NTRS)

    Lee, IN

    1988-01-01

    Prompted by the fact that wind tunnel flutter and oscillatory airload measurements are affected by acoustic vibration mode coupling when the model frequency lies near a wind tunnel resonance frequency, a numerical method has been developed for design sensitivity analysis. Solid curves represent the resonant frequency for the slot, without considering the slot's viscosity. While the viscosity effect decreases with increasing slot width, the viscosity effect also decreases as the slot width approaches zero.

  1. Diagnostic techniques for measurement of aerodynamic noise in free field and reverberant environment of wind tunnels

    NASA Technical Reports Server (NTRS)

    El-Sum, H. M. A.; Mawardi, O. K.

    1973-01-01

    Techniques for studying aerodynamic noise generating mechanisms without disturbing the flow in a free field, and in the reverberation environment of the ARC wind tunnel were investigated along with the design and testing of an acoustic antenna with an electronic steering control. The acoustic characteristics of turbojet as a noise source, detection of direct sound from a source in a reverberant background, optical diagnostic methods, and the design characteristics of a high directivity acoustic antenna. Recommendations for further studies are included.

  2. The role of wind tunnel models in helicopter noise research

    NASA Technical Reports Server (NTRS)

    Sternfeld, H., Jr.; Schaeffer, E. G.

    1986-01-01

    A study was conducted to determine the applicability of using small-scale powered helicopter models operating in nonanechoic wind tunnels to predict the sound pressure levels of full-scale rotor harmonic noise components. The investigation included noise generation due to high-tip-speed effects, tandem-rotor blade/vortex interactions, single rotors operating on test towers, and the interaction between main rotor vortices and tail rotors. In all cases it was found that the pressure time history waveforms characteristic of different noise-generating mechanisms were properly reproduced by the models. Corrections for microphone locations, acoustical reverberation, and tunnel wind velocity were developed. Application of these corrections to the model data were found to yield satisfactory correlation with full-scale sound pressure levels except for the isolated single rotor, where highly transient data, both model and full-scale, recluded good agreement of absolute values.

  3. Aeroelastic instability stoppers for wind tunnel models

    NASA Technical Reports Server (NTRS)

    Doggett, R. V., Jr.; Ricketts, R. H. (Inventor)

    1981-01-01

    A mechanism for constraining models or sections thereof, was wind tunnel tested, deployed at the onset of aeroelastic instability, to forestall destructive vibrations in the model is described. The mechanism includes a pair of arms pivoted to the tunnel wall and straddling the model. Rollers on the ends of the arms contact the model, and are pulled together against the model by a spring stretched between the arms. An actuator mechanism swings the arms into place and back as desired.

  4. Space Shuttle wind tunnel testing program

    NASA Technical Reports Server (NTRS)

    Whitnah, A. M.; Hillje, E. R.

    1984-01-01

    A major phase of the Space Shuttle Vehicle (SSV) Development Program was the acquisition of data through the space shuttle wind tunnel testing program. It became obvious that the large number of configuration/environment combinations would necessitate an extremely large wind tunnel testing program. To make the most efficient use of available test facilities and to assist the prime contractor for orbiter design and space shuttle vehicle integration, a unique management plan was devised for the design and development phase. The space shuttle program is reviewed together with the evolutional development of the shuttle configuration. The wind tunnel testing rationale and the associated test program management plan and its overall results is reviewed. Information is given for the various facilities and models used within this program. A unique posttest documentation procedure and a summary of the types of test per disciplines, per facility, and per model are presented with detailed listing of the posttest documentation.

  5. Some lessons learned with wind tunnels

    NASA Technical Reports Server (NTRS)

    Spearman, M. L.

    1986-01-01

    A review is presented of some of the lessons learned from wind tunnel tests since World War II. Wind tunnels achieved a very high productivity rate during the war due in part to development testing of numerous military aircraft concepts. Following the war, in addition to development testing, a rapid increase in basic research testing occurred in order to explore areas of interest revealed by the conduct of war and to expand on advanced technology that became available from Germany and Italy. The research test areas discussed are those primarily related to the transition from subsonic flight to supersonic flight.

  6. 12. VIEW EAST, BUILDING 12 INTERIOR, WIND TUNNEL 157 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. VIEW EAST, BUILDING 12 INTERIOR, WIND TUNNEL 157 - Naval Surface Warfare Center, Transonic Wind Tunnel Building, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  7. 2. VIEW SOUTH OF TRANSONIC WIND TUNNEL BUILDING AND SUPERSONIC ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VIEW SOUTH OF TRANSONIC WIND TUNNEL BUILDING AND SUPERSONIC WIND TUNNEL BUILDING - Naval Surface Warfare Center, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  8. 8. VIEW SOUTHWEST, INTERIOR VIEW, WIND TUNNEL 139 Naval ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. VIEW SOUTHWEST, INTERIOR VIEW, WIND TUNNEL 139 - Naval Surface Warfare Center, Subsonic Wind Tunnel Building, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  9. 13. VIEW NORTHEAST, BUILDING 12 INTERIOR, WIND TUNNEL FAN ASSEMBLY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. VIEW NORTHEAST, BUILDING 12 INTERIOR, WIND TUNNEL FAN ASSEMBLY - Naval Surface Warfare Center, Transonic Wind Tunnel Building, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  10. 1. VIEW SOUTHWEST OF SUBSONIC WIND TUNNEL BUILDING AND TRANSONIC ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. VIEW SOUTHWEST OF SUBSONIC WIND TUNNEL BUILDING AND TRANSONIC WIND TUNNEL BUILDING - Naval Surface Warfare Center, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  11. 7. VIEW WEST OF SCALE ROOM IN FULLSCALE WIND TUNNEL; ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. VIEW WEST OF SCALE ROOM IN FULL-SCALE WIND TUNNEL; SCALES ARE USED TO MEASURE FORCES ACTING ON MODEL AIRCRAFT SUSPENDED ABOVE. - NASA Langley Research Center, Full-Scale Wind Tunnel, 224 Hunting Avenue, Hampton, Hampton, VA

  12. 2. VIEW SOUTH OF WIND TUNNEL 138 AND COOLING SYSTEM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VIEW SOUTH OF WIND TUNNEL 138 AND COOLING SYSTEM 140, NORTH ELEVATION - Naval Surface Warfare Center, Subsonic Wind Tunnel Building, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  13. 7. VIEW NORTHWEST OF SUBSONIC WIND TUNNEL BUILDING TO TRANSONIC ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. VIEW NORTHWEST OF SUBSONIC WIND TUNNEL BUILDING TO TRANSONIC WIND TUNNEL BUILDING - Naval Surface Warfare Center, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  14. 5. VIEW NORTHWEST OF SUBSONIC WIND TUNNEL BUILDING TO TRANSONIC ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. VIEW NORTHWEST OF SUBSONIC WIND TUNNEL BUILDING TO TRANSONIC WIND TUNNEL BUILDING - Naval Surface Warfare Center, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  15. 2. VIEW SOUTH OF WIND TUNNEL 157, NORTH ELEVATION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VIEW SOUTH OF WIND TUNNEL 157, NORTH ELEVATION - Naval Surface Warfare Center, Transonic Wind Tunnel Building, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  16. 4. VIEW NORTHWEST OF SUPERSONIC WIND TUNNEL BUILDING TO TRANSONIC ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. VIEW NORTHWEST OF SUPERSONIC WIND TUNNEL BUILDING TO TRANSONIC WIND TUNNEL BUILDING - Naval Surface Warfare Center, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  17. 3. VIEW SOUTHEAST OF TRANSONIC WIND TUNNEL BUILDING TO SUBSONIC ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW SOUTHEAST OF TRANSONIC WIND TUNNEL BUILDING TO SUBSONIC WIND TUNNEL BUILDING - Naval Surface Warfare Center, Bounded by Clara Barton Parkway & McArthur Boulevard, Silver Spring, Montgomery County, MD

  18. 6. VIEW OF FIVEFOOT WIND TUNNEL WITH AIR STRAIGHTENER AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. VIEW OF FIVE-FOOT WIND TUNNEL WITH AIR STRAIGHTENER AND OPERATOR STATION IN FOREGROUND (1991). - Wright-Patterson Air Force Base, Area B, Building No. 19, Five-Foot Wind Tunnel, Dayton, Montgomery County, OH

  19. Wind tunnel simulation of Martian sand storms

    NASA Technical Reports Server (NTRS)

    Greeley, R.

    1980-01-01

    The physics and geological relationships of particles driven by the wind under near Martian conditions were examined in the Martian Surface Wind Tunnel. Emphasis was placed on aeolian activity as a planetary process. Threshold speeds, rates of erosion, trajectories of windblown particles, and flow fields over various landforms were among the factors considered. Results of experiments on particles thresholds, rates of erosion, and the effects of electrostatics on particles in the aeolian environment are presented.

  20. Flight effects on the aerodynamic and acoustic characteristics of inverted profile coannular nozzles, volume 2. [supersonic cruise aircraft research wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Kozlowski, H.; Packman, A. B.

    1978-01-01

    Data from the acoustic tests of the convergent reference nozzle and the 0.75 area ratio coannular nozzle are presented in tables. Data processing routines used to scale the acoustic data and to correct the data for atmospheric attenuation are included.

  1. Spinoff from Wind Tunnel Technology

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Douglas Juanarena, a former NASA Langley instrument design engineer, found a solution to the problem of long, repetitive tunnel runs needed to measure airflow pressures. Electronically scanned pressure (ESP) replaced mechanical systems with electronic sensors. Juanarena licensed the NASA-patented technology and now manufactures ESP modules for research centers, aerospace companies, etc.

  2. 7 x 10-Foot Atmospheric Wind Tunnel (AWT)

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Force Test set-up in 7 x 10-Foot Atmospheric Wind Tunnel (AWT). In 1928, the NACA decided to replace its original Atmospheric Wind Tunnel (AWT #1) with two tunnels--the 5-foot vertical tunnel and a 7 by 10 foot rectangular throat tunnel. Both were open-throat, closed-return-passage tunnels and were housed in the same building the first wind tunnel had been located in. While the 5-foot vertical tunnel was to be used mainly for spin tests, the 7x10 was an all-purpose tunnel although the main intent was to study stability and control problems. Construction was completed in the summer of 1930; calibration later that same year. The balance was installed and the tunnel went into operation in early 1931. There was a 6-component balance in this wind tunnel. The balance could support either static or rotation tests.

  3. WIND TUNNEL SIMULATIONS OF POLLUTION FROM ROADWAYS

    EPA Science Inventory

    A wind tunnel study has been conducted to examine the influence of roadway configurations and nearby structures on the flow and dispersion of traffic related pollutant concentrations within a few hundred meters of the roadway. The study focused four selected configurations (all w...

  4. AWT aerodynamic design status. [Altitude Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Davis, Milt W.

    1984-01-01

    The aerodynamic design of the NASA Altitude Wind Tunnel is presented in viewgraph format. The main topics covered are: analysis of a plenum evacuation system; airline definition and pressure loss code development; contraction geometry and code analysis; and design of the two stage fan. Flow characteristics such as pressure ratio, mach number distribution, adiabatic efficiency, and losses are shown.

  5. Detecting Foreign Particles in Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Sharp, H. L.; Hogenson, P. A.; Emde, W. D.

    1986-01-01

    Simple scratch test tells whether particles, which distort results, present in test. Detector developed for tests of abrasion resistance of flexible insulation blankets. Now, when detector indicates particles present in test, results interpreted accordingly. Small pits and scratches on metal foil indicate particles struck surface during wind-tunnel test. Detector used in tests of paints and coatings to determine whether abrasive particles present.

  6. Aeronautical Facilities Catalogue. Volume 1: Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Penaranda, F. E. (Compiler); Freda, M. S. (Compiler)

    1985-01-01

    Domestic and foreign wind tunnel facilities are enumerated and their technical parameters are described. Data pertinent to managers and engineers are presented. Facilities judged comparable in testing capability are noted and grouped together. Several comprehensive cross-indexes and charts are included.

  7. A construction technique for wind tunnel models

    NASA Technical Reports Server (NTRS)

    Lawing, P. L.; Sandefur, P. G., Jr.; Wood, W. H.

    1981-01-01

    High strength, good surface finish, and corrosion resistance are imparted to miniature wind tunnel models by machining pressure channels as integral part of model. Pattern for pressure channels is scribed, machined, or photoetched before channels are drilled. Mating surfaces for channels are flashed and then diffusion brazed together.

  8. Prismatic Blade Measuring on a Wind Tunnel

    NASA Astrophysics Data System (ADS)

    Epikaridis, P.; Sedlak, k.; Stech, J.

    2013-04-01

    The results from measurement on the straight blade cascade are presented in the paper. The cascade is placed at the outlet of wind tunnel in ŠKODA POWER experimental base. The results in the form of velocity and loss fields behind blade cascade as well as the distribution of the loss coefficient in selected cross-section are evaluated.

  9. Flight effects on the aerodynamic and acoustic characteristics of inverted profile coannular nozzles, volume 3. [supersonic cruise aircraft research wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Kozlowski, H.; Packman, A. B.

    1978-01-01

    Acoustic data from tests of the 0.75 area ratio coannular nozzle with ejector and the 1.2 area ratio coannular are presented in tables. Aerodynamic data acquired for the four test configurations are included.

  10. 40 CFR Table F-2 to Subpart F of... - Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Particle Sizes and Wind Speeds for Full... Part 53—Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and Static Chamber Test Primary Partical Mean Size a (µm) Full Wind Tunnel Test 2 km/hr 24 km/hr...

  11. Wind Tunnel Test of the SMART Active Flap Rotor

    NASA Technical Reports Server (NTRS)

    Straub, Friedrich K.; Anand, Vaidyanthan R.; Birchette, Terrence S.; Lau, Benton H.

    2009-01-01

    Boeing and a team from Air Force, NASA, Army, DARPA, MIT, UCLA, and U. of Maryland have successfully completed a wind-tunnel test of the smart material actuated rotor technology (SMART) rotor in the 40- by 80-foot wind-tunnel of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center. The Boeing SMART rotor is a full-scale, five-bladed bearingless MD 900 helicopter rotor modified with a piezoelectric-actuated trailing edge flap on each blade. The eleven-week test program evaluated the forward flight characteristics of the active-flap rotor at speeds up to 155 knots, gathered data to validate state-of-the-art codes for rotor aero-acoustic analysis, and quantified the effects of open and closed loop active flap control on rotor loads, noise, and performance. The test demonstrated on-blade smart material control of flaps on a full-scale rotor for the first time in a wind tunnel. The effectiveness of the active flap control on noise and vibration was conclusively demonstrated. Results showed significant reductions up to 6dB in blade-vortex-interaction and in-plane noise, as well as reductions in vibratory hub loads up to 80%. Trailing-edge flap deflections were controlled within 0.1 degrees of the commanded value. The impact of the active flap on control power, rotor smoothing, and performance was also demonstrated. Finally, the reliability of the flap actuation system was successfully proven in more than 60 hours of wind-tunnel testing.

  12. Smart wing wind tunnel test results

    NASA Astrophysics Data System (ADS)

    Scherer, Lewis B.; Martin, Christopher A.; Appa, Kari; Kudva, Jayanth N.; West, Mark N.

    1997-05-01

    The use of smart materials technologies can provide unique capabilities in improving aircraft aerodynamic performance. Northrop Grumman built and tested a 16% scale semi-span wind tunnel model of the F/A-18 E/F for the on-going DARPA/WL Smart Materials and Structures-Smart Wing Program. Aerodynamic performance gains to be validated included increase in the lift to drag ratio, increased pitching moment (Cm), increased rolling moment (Cl) and improved pressure distribution. These performance gains were obtained using hingeless, contoured trailing edge control surfaces with embedded shape memory alloy (SMA) wires and spanwise wing twist via a SMA torque tube and are compared to a conventional wind tunnel model with hinged control surfaces. This paper presents an overview of the results from the first wind tunnel test performed at the NASA Langley's 16 ft Transonic Dynamic Tunnel. Among the benefits demonstrated are 8 - 12% increase in rolling moment due to wing twist, a 10 - 15% increase in rolling moment due to contoured aileron, and approximately 8% increase in lift due to contoured flap, and improved pressure distribution due to trailing edge control surface contouring.

  13. Unsteady two dimensional airloads acting on oscillating thin airfoils in subsonic ventilated wind tunnels

    NASA Technical Reports Server (NTRS)

    Fromme, J.; Golberg, M.

    1978-01-01

    The numerical calculation of unsteady two dimensional airloads which act upon thin airfoils in subsonic ventilated wind tunnels was studied. Neglecting certain quadrature errors, Bland's collocation method is rigorously proved to converge to the mathematically exact solution of Bland's integral equation, and a three way equivalence was established between collocation, Galerkin's method and least squares whenever the collocation points are chosen to be the nodes of the quadrature rule used for Galerkin's method. A computer program displayed convergence with respect to the number of pressure basis functions employed, and agreement with known special cases was demonstrated. Results are obtained for the combined effects of wind tunnel wall ventilation and wind tunnel depth to airfoil chord ratio, and for acoustic resonance between the airfoil and wind tunnel walls. A boundary condition is proposed for permeable walls through which mass flow rate is proportional to pressure jump.

  14. Application Of Artificial Intelligence To Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Lo, Ching F.; Steinle, Frank W., Jr.

    1989-01-01

    Report discusses potential use of artificial-intelligence systems to manage wind-tunnel test facilities at Ames Research Center. One of goals of program to obtain experimental data of better quality and otherwise generally increase productivity of facilities. Another goal to increase efficiency and expertise of current personnel and to retain expertise of former personnel. Third goal to increase effectiveness of management through more efficient use of accumulated data. System used to improve schedules of operation and maintenance of tunnels and other equipment, assignment of personnel, distribution of electrical power, and analysis of costs and productivity. Several commercial artificial-intelligence computer programs discussed as possible candidates for use.

  15. Anechoic wind tunnel study of turbulence effects on wind turbine broadband noise

    NASA Technical Reports Server (NTRS)

    Loyd, B.; Harris, W. L.

    1995-01-01

    This paper describes recent results obtained at MIT on the experimental and theoretical modelling of aerodynamic broadband noise generated by a downwind rotor horizontal axis wind turbine. The aerodynamic broadband noise generated by the wind turbine rotor is attributed to the interaction of ingested turbulence with the rotor blades. The turbulence was generated in the MIT anechoic wind tunnel facility with the aid of biplanar grids of various sizes. The spectra and the intensity of the aerodynamic broadband noise have been studied as a function of parameters which characterize the turbulence and of wind turbine performance parameters. Specifically, the longitudinal integral scale of turbulence, the size scale of turbulence, the number of turbine blades, and free stream velocity were varied. Simultaneous measurements of acoustic and turbulence signals were made. The sound pressure level was found to vary directly with the integral scale of the ingested turbulence but not with its intensity level. A theoretical model based on unsteady aerodynamics is proposed.

  16. Calibration of transonic and supersonic wind tunnels

    NASA Technical Reports Server (NTRS)

    Reed, T. D.; Pope, T. C.; Cooksey, J. M.

    1977-01-01

    State-of-the art instrumentation and procedures for calibrating transonic (0.6 less than M less than 1.4) and supersonic (M less than or equal to 3.5) wind tunnels were reviewed and evaluated. Major emphasis was given to transonic tunnels. Continuous, blowdown and intermittent tunnels were considered. The required measurements of pressure, temperature, flow angularity, noise and humidity were discussed, and the effects of measurement uncertainties were summarized. A comprehensive review of instrumentation currently used to calibrate empty tunnel flow conditions was included. The recent results of relevant research are noted and recommendations for achieving improved data accuracy are made where appropriate. It is concluded, for general testing purposes, that satisfactory calibration measurements can be achieved in both transonic and supersonic tunnels. The goal of calibrating transonic tunnels to within 0.001 in centerline Mach number appears to be feasible with existing instrumentation, provided correct calibration procedures are carefully followed. A comparable accuracy can be achieved off-centerline with carefully designed, conventional probes, except near Mach 1. In the range 0.95 less than M less than 1.05, the laser Doppler velocimeter appears to offer the most promise for improved calibration accuracy off-centerline.

  17. Preliminary wind tunnel tests on the pedal wind turbine

    NASA Astrophysics Data System (ADS)

    Vinayagalingam, T.

    1980-06-01

    High solidity-low speed wind turbines are relatively simple to construct and can be used advantageously in many developing countries for such direct applications as water pumping. Established designs in this class, such as the Savonius and the American multiblade rotors, have the disadvantage that their moving surfaces require a rigid construction, thereby rendering large units uneconomical. In this respect, the pedal wind turbine recently reported by the author and which incorporates sail type rotors offers a number of advantages. This note reports preliminary results from a series of wind tunnel tests which were carried out to assess the aerodynamic torque and power characteristics of the turbine.

  18. Low-frequency rotational noise in closed-test-section wind tunnels

    NASA Technical Reports Server (NTRS)

    Mosher, Marianne

    1987-01-01

    The effects of closed-section wind-tunnel walls on the sound field radiated from a helicopter rotor are investigated by means of numerical simulations, summarizing the findings reported by Mosher (1986). The techniques used to model the rotor and the test section (including geometry, wall absorption, and measurement location) are outlined, and the results are presented in extensive tables and graphs. It is found that first-harmonic acoustic measurements obtained in a hard-walled wind tunnel twice as wide as the rotor diameter do not accurately represent the free-field rotational noise, that the relationship between the sound-pressure levels in the wind tunnel and in the free field is complex, that multiple near-field measurements are needed to characterize the direct acoustic field of the rotor, and that absorptive linings are of little value in enlarging the accurate-measurement zone.

  19. Cryogenic Wind Tunnel Models. Design and Fabrication

    NASA Technical Reports Server (NTRS)

    Young, C. P., Jr. (Compiler); Gloss, B. B. (Compiler)

    1983-01-01

    The principal motivating factor was the National Transonic Facility (NTF). Since the NTF can achieve significantly higher Reynolds numbers at transonic speeds than other wind tunnels in the world, and will therefore occupy a unique position among ground test facilities, every effort is being made to ensure that model design and fabrication technology exists to allow researchers to take advantage of this high Reynolds number capability. Since a great deal of experience in designing and fabricating cryogenic wind tunnel models does not exist, and since the experience that does exist is scattered over a number of organizations, there is a need to bring existing experience in these areas together and share it among all interested parties. Representatives from government, the airframe industry, and universities are included.

  20. Photogrammetry Applied to Wind Tunnel Testing

    NASA Technical Reports Server (NTRS)

    Liu, Tian-Shu; Cattafesta, L. N., III; Radeztsky, R. H.; Burner, A. W.

    2000-01-01

    In image-based measurements, quantitative image data must be mapped to three-dimensional object space. Analytical photogrammetric methods, which may be used to accomplish this task, are discussed from the viewpoint of experimental fluid dynamicists. The Direct Linear Transformation (DLT) for camera calibration, used in pressure sensitive paint, is summarized. An optimization method for camera calibration is developed that can be used to determine the camera calibration parameters, including those describing lens distortion, from a single image. Combined with the DLT method, this method allows a rapid and comprehensive in-situ camera calibration and therefore is particularly useful for quantitative flow visualization and other measurements such as model attitude and deformation in production wind tunnels. The paper also includes a brief description of typical photogrammetric applications to temperature- and pressure-sensitive paint measurements and model deformation measurements in wind tunnels.

  1. An Automatic Speed Control for Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Zahm, A F

    1928-01-01

    Described here is an automatic control that has been used in several forms in wind tunnels at the Washington Navy Yard. The form now in use with the 8-foot tunnel at the Navy Yard is considered here. Details of the design and operation of the automatic control system are given. Leads from a Pitot tube are joined to an inverted cup manometer located above a rheostat. When the sliding weight of this instrument is set to a given notch, say for 40 m.p.h, the beam tip vibrates between two electric contacts that feed the little motor. Thus, when the wind is too strong or too weak, the motor automatically throws the rheostat slide forward and backward. If it failed to function well, the operator would notice the effect on his meniscus, and would operate the hand control by merely pressing the switch.

  2. Condensation in hypersonic nitrogen wind tunnels

    NASA Technical Reports Server (NTRS)

    Lederer, Melissa A.; Yanta, William J.; Ragsdale, William C.; Hudson, Susan T.; Griffith, Wayland C.

    1990-01-01

    Experimental observations and a theoretical model for the onset and disappearance of condensation are given for hypersonic flows of pure nitrogen at M = 10, 14 and 18. Measurements include Pitot pressures, static pressures and laser light scattering experiments. These measurements coupled with a theoretical model indicate a substantial non-equilibrium supercooling of the vapor phase beyond the saturation line. Typical results are presented with implications for the design of hypersonic wind tunnel nozzles.

  3. Residual interference and wind tunnel wall adaption

    NASA Technical Reports Server (NTRS)

    Mokry, Miroslav

    1989-01-01

    Measured flow variables near the test section boundaries, used to guide adjustments of the walls in adaptive wind tunnels, can also be used to quantify the residual interference. Because of a finite number of wall control devices (jacks, plenum compartments), the finite test section length, and the approximation character of adaptation algorithms, the unconfined flow conditions are not expected to be precisely attained even in the fully adapted stage. The procedures for the evaluation of residual wall interference are essentially the same as those used for assessing the correction in conventional, non-adaptive wind tunnels. Depending upon the number of flow variables utilized, one can speak of one- or two-variable methods; in two dimensions also of Schwarz- or Cauchy-type methods. The one-variable methods use the measured static pressure and normal velocity at the test section boundary, but do not require any model representation. This is clearly of an advantage for adaptive wall test section, which are often relatively small with respect to the test model, and for the variety of complex flows commonly encountered in wind tunnel testing. For test sections with flexible walls the normal component of velocity is given by the shape of the wall, adjusted for the displacement effect of its boundary layer. For ventilated test section walls it has to be measured by the Calspan pipes, laser Doppler velocimetry, or other appropriate techniques. The interface discontinuity method, also described, is a genuine residual interference assessment technique. It is specific to adaptive wall wind tunnels, where the computation results for the fictitious flow in the exterior of the test section are provided.

  4. Python Engine Installed in Altitude Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1949-01-01

    An engine mechanic checks instrumentation prior to an investigation of engine operating characteristics and thrust control of a large turboprop engine with counter-rotating propellers under high-altitude flight conditions in the 20-foot-dianieter test section of the Altitude Wind Tunnel at the Lewis Flight Propulsion Laboratory of the National Advisory Committee for Aeronautics, Cleveland, Ohio, now known as the John H. Glenn Research Center at Lewis Field.

  5. SUBSONIC WIND TUNNEL PERFORMANCE ANALYSIS SOFTWARE

    NASA Technical Reports Server (NTRS)

    Eckert, W. T.

    1994-01-01

    This program was developed as an aid in the design and analysis of subsonic wind tunnels. It brings together and refines previously scattered and over-simplified techniques used for the design and loss prediction of the components of subsonic wind tunnels. It implements a system of equations for determining the total pressure losses and provides general guidelines for the design of diffusers, contractions, corners and the inlets and exits of non-return tunnels. The algorithms used in the program are applicable to compressible flow through most closed- or open-throated, single-, double- or non-return wind tunnels or ducts. A comparison between calculated performance and that actually achieved by several existing facilities produced generally good agreement. Any system through which air is flowing which involves turns, fans, contractions etc. (e.g., an HVAC system) may benefit from analysis using this software. This program is an update of ARC-11138 which includes PC compatibility and an improved user interface. The method of loss analysis used by the program is a synthesis of theoretical and empirical techniques. Generally, the algorithms used are those which have been substantiated by experimental test. The basic flow-state parameters used by the program are determined from input information about the reference control section and the test section. These parameters were derived from standard relationships for compressible flow. The local flow conditions, including Mach number, Reynolds number and friction coefficient are determined for each end of each component or section. The loss in total pressure caused by each section is calculated in a form non-dimensionalized by local dynamic pressure. The individual losses are based on the nature of the section, local flow conditions and input geometry and parameter information. The loss forms for typical wind tunnel sections considered by the program include: constant area ducts, open throat ducts, contractions, constant

  6. Control Room - 10ft x 10ft Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1955-01-01

    One of three control panels in the control room of the Lewis Unitary Plan Wind Tunnel. The tunnel model (top center) shows position of the valves that control the operating cycle of the tunnel. The TV monitor screens can be connected to any of 3 closed-circuit TV cameras used to monitor tunnel components.

  7. Comparison Between Field Data and NASA Ames Wind Tunnel Data

    SciTech Connect

    Corbus, D.

    2005-11-01

    The objective of this analysis is to compare the measured data from the NASA Ames wind tunnel experiment to those collected in the field at the National Wind Technology Center (NWTC) with the same turbine configuration. The results of this analysis provide insight into what measurements can be made in the field as opposed to wind tunnel testing.

  8. Wind tunnel tests of a free yawing downwind wind turbine

    NASA Astrophysics Data System (ADS)

    Verelst, D. R. S.; Larsen, T. J.; van Wingerden, J. W.

    2014-12-01

    This research paper presents preliminary results on a behavioural study of a free yawing downwind wind turbine. A series of wind tunnel tests was performed at the TU Delft Open Jet Facility with a three bladed downwind wind turbine and a rotor radius of 0.8 meters. The setup includes an off the shelf three bladed hub, nacelle and generator on which relatively flexible blades are mounted. The tower support structure has free yawing capabilities provided at the base. A short overview on the technical details of the experiment is given as well as a brief summary of the design process. The discussed test cases show that the turbine is stable while operating in free yawing conditions. Further, the effect of the tower shadow passage on the blade flapwise strain measurement is evaluated. Finally, data from the experiment is compared with preliminary simulations using DTU Wind Energy's aeroelastic simulation program HAWC2.

  9. Overview of the 1989 Wind Tunnel Calibration Workshop

    NASA Technical Reports Server (NTRS)

    Henderson, Arthur, Jr.; Mckinney, L. Wayne

    1993-01-01

    An overview of the 1989 Wind Tunnel Calibration Workshop held at NASA LaRC in Hampton, VA on 19-20 Apr. 1989 is presented. The purpose of the Workshop was to explore wind tunnel calibration requirements as they relate to test quality and data accuracy, with the ultimate goal of developing wind tunnel calibration requirements for the major NASA wind tunnels at ARC, LaRC, and LeRC. The two sessions addressed the following topics: (1) what constitutes a properly calibrated wind tunnel; and (2) the status of calibration of NASA's major wind tunnels. The most significant contributions to the stated goals are highlighted, and the consensus of the Workshop's conclusions and recommendations regarding formulation and implementation of that goal are presented.

  10. Blowdown Wind Tunnels: Latest Citations from the Aerospace Database

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The bibliography contains citations concerning the design, construction, operation, and performance of blowdown wind tunnels. The use of compressed gas, mechanical piston, or combustion exhaust to provide continuous or short-duration operation from transonic to hypersonic approach velocities is discussed. Also covered are invasive and non-invasive aerothermodynamic instrumentation, data acquisition and reduction techniques, and test reports on aerospace components. Comprehensive coverage of wind tunnel force balancing systems and supersonic wind tunnels are covered in separate bibliographies.

  11. 7 x 10 Foot Atmospheric Wind Tunnel (AWT)

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Construction of 7 x 10 Foot Atmospheric Wind Tunnel (AWT). In 1928, the NACA decided to replace its original Atmospheric Wind Tunnel (AWT #1) with two tunnels--the 5-foot vertical tunnel and a 7 by 10 foot rectangular throat tunnel. Both were open-throat, closed-return-passage tunnels. While the 5 foot vertical tunnel was to be used mainly for spin tests, the 7x10 was an all-purpose tunnel although the main intent was to study stability and control problems. Construction was completed in the summer of 1930; calibration later that same year. The balance was installed and the tunnel went into operation in early 1931. The Warwick Machine Co. of Newport News, Virginia had the contract to fabricate and erection the 7x10 Foot tunnel for a total cost of $18,018.90. The balance was made by Fairbanks, Morse and Co., of Baltimore, Maryland for $2,544.00. The honeycomb was made by the Berkley Machine Works and Foundry Co., Inc. of Norfolk, Virginia for $1,580 and the control panel by Clark Controller Co. of Cleveland, OH for $1,153. Published in NACA TR No. 412, 'The 7 by 10 Foot Wind Tunnel of the National Advisory Committee for Aeronautics,' by Thomas A. Harris, 1932; Reference Notes on the 'Atmospheric Wind Tunnel' in the Langley Historical Archives (D. Baals notes on wind tunnels).

  12. Aeolian sand transport: a wind tunnel model

    NASA Astrophysics Data System (ADS)

    Dong, Zhibao; Liu, Xiaoping; Wang, Hongtao; Wang, Xunming

    2003-09-01

    Wind sand transport is an important geological process on earth and some other planets. Formulating the wind sand transport model has been of continuing significance. Majority of the existing models relate sand transport rate to the wind shear velocity based on dynamic analysis. However, the wind shear velocity readapted to blown sand is difficult to determine from the measured wind profiles when sand movement occurs, especially at high wind velocity. Moreover, the effect of grain size on sand transport is open to argument. Detailed wind tunnel tests were carried out with respect to the threshold velocity, threshold shear velocity, and transport rate of differently sized, loose dry sand at different wind velocities to reformulate the transport model. The results suggest that the relationship between threshold shear velocity and grain size basically follow the Bagnold-type equation for the grain size d>0.1 mm. However, the threshold coefficient A in the equation is not constant as suggested by Bagnold, but decreases with the particle Reynolds number. The threshold velocity at the centerline height of the wind tunnel proved to be directly proportional to the square root of grain diameter. Attempts have been made to relate sand transport rate to both the wind velocity and shear velocity readapted to the blown sand movement. The reformulated transport model for loose dry sand follows the modified O'Brien-Rindlaub-type equation: Q= f1( d)(1- Ru) 2( ρ/ g) V3, or the modified Bagnold-type equation: Q= f2( d)(1- Rt) 0.25( ρ/ g) U*3. Where Q is the sand transport rate, the sand flux per unit time and per unit width, in kg m -1 s -1; ρ is the air density, 1.25 kg m -3; g is the acceleration due to gravity, 9.81 m s -2; Ru= Vt/ V; Rt= U*t/ U*; V is the wind velocity at the centerline of the wind tunnel, in m s -1; Vt is the threshold velocity measured at the same height as V, in m s -1; U* is the shear velocity with saltating flux, in m s -1; U*t is threshold shear

  13. Tone Noise of Three Supersonic Helical Tip Speed Propellers in a Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Dittmar, J. H.; Jeracki, R. J.; Blaha, B. J.

    1979-01-01

    Three supersonic helical tip speed propellers were tested in the NASA Lewis 8- by 6-foot wind tunnel. This is a perforated-wall wind tunnel but it does not have acoustic damping material on its walls. The propellers were tested at tunnel through flow Mach numbers of 0.6, 0.7, 0.75, 0.8, and 0.85 with different rotational speeds and blade setting angles. The three propellers, which had approximately the same aerodynamic performance, incorporated different plan forms and different amounts of sweep and yielded different near field noise levels. The acoustically designed propeller had 45 deg of tip sweep and was significantly quieter at M = 0.8 cruise than the straight bladed propeller. The intermediate 30 deg tip sweep propeller, which was swept for aerodynamic purposes, exhibited noise that was between the other two propellers. Noise trends with varying helical tip Mach number and blade loading were also observed.

  14. Rocket Plume Scaling for Orion Wind Tunnel Testing

    NASA Technical Reports Server (NTRS)

    Brauckmann, Gregory J.; Greathouse, James S.; White, Molly E.

    2011-01-01

    A wind tunnel test program was undertaken to assess the jet interaction effects caused by the various solid rocket motors used on the Orion Launch Abort Vehicle (LAV). These interactions of the external flowfield and the various rocket plumes can cause localized aerodynamic disturbances yielding significant and highly non-linear control amplifications and attenuations. This paper discusses the scaling methodologies used to model the flight plumes in the wind tunnel using cold air as the simulant gas. Comparisons of predicted flight, predicted wind tunnel, and measured wind tunnel forces-and-moments and plume flowfields are made to assess the effectiveness of the selected scaling methodologies.

  15. Nano-ADEPT Aeroloads Wind Tunnel Test

    NASA Technical Reports Server (NTRS)

    Smith, Brandon; Yount, Bryan; Kruger, Carl; Brivkalns, Chad; Makino, Alberto; Cassell, Alan; Zarchi, Kerry; McDaniel, Ryan; Ross, James; Wercinski, Paul; Venkatapathy, Ethiraj; Swanson, Gregory; Gold, Nili

    2016-01-01

    A wind tunnel test of the Adaptable Deployable Entry and Placement Technology (ADEPT) was conducted in April 2015 at the US Army's 7 by10 Foot Wind Tunnel located at NASA Ames Research Center. Key geometric features of the fabric test article were a 0.7 meter deployed base diameter, a 70 degree half-angle forebody cone angle, eight ribs, and a nose-to-base radius ratio of 0.7. The primary objective of this wind tunnel test was to obtain static deflected shape and pressure distributions while varying pretension at dynamic pressures and angles of attack relevant to entry conditions at Earth, Mars, and Venus. Other objectives included obtaining aerodynamic force and moment data and determining the presence and magnitude of any dynamic aeroelastic behavior (buzz/flutter) in the fabric trailing edge. All instrumentation systems worked as planned and a rich data set was obtained. This paper describes the test articles, instrumentation systems, data products, and test results. Four notable conclusions are drawn. First, test data support adopting a pre-tension lower bound of 10 foot pounds per inch for Nano-ADEPT mission applications in order to minimize the impact of static deflection. Second, test results indicate that the fabric conditioning process needs to be reevaluated. Third, no flutter/buzz of the fabric was observed for any test condition and should also not occur at hypersonic speeds. Fourth, translating one of the gores caused ADEPT to generate lift without the need for a center of gravity offset. At hypersonic speeds, the lift generated by actuating ADEPT gores could be used for vehicle control.

  16. Comparison of propeller cruise noise data taken in the NASA Lewis 8- by 6-foot wind tunnel with other tunnel and flight data

    NASA Technical Reports Server (NTRS)

    Dittmar, James

    1989-01-01

    The noise of advanced high speed propeller models measured in the NASA 8- by 6-foot wind tunnel has been compared with model propeller noise measured in another tunnel and with full-scale propeller noise measured in flight. Good agreement was obtained for the noise of a model counterrotation propeller tested in the 8- by 6-foot wind tunnel and in the acoustically treated test section of the Boeing Transonic Wind Tunnel. This good agreement indicates the relative validity of taking cruise noise data on a plate in the 8- by 6-foot wind tunnel compared with the free-field method in the Boeing tunnel. Good agreement was also obtained for both single rotation and counter-rotation model noise comparisons with full-scale propeller noise in flight. The good scale model to full-scale comparisons indicate both the validity of the 8- by 6-foot wind tunnel data and the ability to scale to full size. Boundary layer refraction on the plate provides a limitation to the measurement of forward arc noise in the 8- by 6-foot wind tunnel at the higher harmonics of the blade passing tone. The sue of a validated boundary layer refraction model to adjust the data could remove this limitation.

  17. Comparison of propeller cruise noise data taken in the NASA Lewis 8- by 6-foot wind tunnel with other tunnel and flight data

    NASA Technical Reports Server (NTRS)

    Dittmar, James H.

    1989-01-01

    The noise of advanced high speed propeller models measured in the NASA 8- by 6-foot wind tunnel has been compared with model propeller noise measured in another tunnel and with full-scale propeller noise measured in flight. Good agreement was obtained for the noise of a model counterrotation propeller tested in the 8- by 6-foot wind tunnel and in the acoustically treated test section of the Boeing Transonic Wind Tunnel. This good agreement indicates the relative validity of taking cruise noise data on a plate in the 8- by 6-foot wind tunnel compared with the free-field method in the Boeing tunnel. Good agreement was also obtained for both single rotation and counter-rotation model noise comparisons with full-scale propeller noise in flight. The good scale model to full-scale comparisons indicate both the validity of the 8- by 6-foot wind tunnel data and the ability to scale to full size. Boundary layer refraction on the plate provides a limitation to the measurement of forward arc noise in the 8- by 6-foot wind tunnel at the higher harmonics of the blade passing tone. The use of a validated boundary layer refraction model to adjust the data could remove this limitation.

  18. Aeroservoelastic Wind-Tunnel Test of the SUGAR Truss Braced Wing Wind-Tunnel Model

    NASA Technical Reports Server (NTRS)

    Scott, Robert C.; Allen, Timothy J.; Funk, Christie J.; Castelluccio, Mark A.; Sexton, Bradley W.; Claggett, Scott; Dykman, John; Coulson, David A.; Bartels, Robert E.

    2015-01-01

    The Subsonic Ultra Green Aircraft Research (SUGAR) Truss-Braced Wing (TBW) aeroservoelastic (ASE) wind-tunnel test was conducted in the NASA Langley Transonic Dynamics Tunnel (TDT) and was completed in April, 2014. The primary goals of the test were to identify the open-loop flutter boundary and then demonstrate flutter suppression. A secondary goal was to demonstrate gust load alleviation (GLA). Open-loop flutter and limit cycle oscillation onset boundaries were identified for a range of Mach numbers and various angles of attack. Two sets of control laws were designed for the model and both sets of control laws were successful in suppressing flutter. Control laws optimized for GLA were not designed; however, the flutter suppression control laws were assessed using the TDT Airstream Oscillation System. This paper describes the experimental apparatus, procedures, and results of the TBW wind-tunnel test. Acquired system ID data used to generate ASE models is also discussed.2 study.

  19. National Wind Tunnel Complex (NWTC) Project Archive

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This archive was designed with three purposes in mind. First, it was designed as a medium for providing our program deliverables to our customers-NASA and the industry team. Secondly, it was designed to be "The" critical resource for a program restart. Finally, the archive should serve as an invaluable technical resource for aerodynamic and wind tunnel science. The documents are stored in both native format and, for the majority of the documents, in scanned format. The end user is responsible for having applications for viewing and using native and scanned format documents.

  20. Integral equations for flows in wind tunnels

    NASA Technical Reports Server (NTRS)

    Fromme, J. A.; Golberg, M. A.

    1979-01-01

    This paper surveys recent work on the use of integral equations for the calculation of wind tunnel interference. Due to the large number of possible physical situations, the discussion is limited to two-dimensional subsonic and transonic flows. In the subsonic case, the governing boundary value problems are shown to reduce to a class of Cauchy singular equations generalizing the classical airfoil equation. The theory and numerical solution are developed in some detail. For transonic flows nonlinear singular equations result, and a brief discussion of the work of Kraft and Kraft and Lo on their numerical solution is given. Some typical numerical results are presented and directions for future research are indicated.

  1. 7 x 10-Foot Atmospheric Wind Tunnel (AWT)

    NASA Technical Reports Server (NTRS)

    1934-01-01

    Smoke generator for 7 x 10-Foot Atmospheric Wind Tunnel (AWT) (left center); Force Test Set-Up in the center. In 1928, the NACA decided to replace its original Atmospheric Wind Tunnel (AWT #1) with two tunnels--the 5-foot vertical tunnel and a 7 by 10 foot rectangular throat tunnel. Both were open-throat, closed-return-passage tunnels. While the 5-foot vertical tunnel was to be used mainly for spin tests, the 7x10 was an all-purpose tunnel although the main intent was to study stability and control problems. Construction was completed in the summer of 1930; calibration later that same year. The balance was installed and the tunnel went into operation in early 1931.

  2. Immersion and contact freezing experiments in the Mainz wind tunnel laboratory

    NASA Astrophysics Data System (ADS)

    Eppers, Oliver; Mayer, Amelie; Diehl, Karoline; Mitra, Subir; Borrmann, Stephan; Szakáll, Miklós

    2016-04-01

    Immersion and contact freezing are of outmost important ice nucleation processes in mixed phase clouds. Experimental studies are carried out in the Mainz vertical wind tunnel laboratory in order to characterize these nucleation processes for different ice nucleating particles (INP), such as for mineral dust or biological particles. Immersion freezing is investigated in our laboratory with two different experimental techniques, both attaining contact-free levitation of liquid droplets and cooling of the surrounding air down to about -25 °C. In an acoustic levitator placed in the cold room of our laboratory, drops with diameters of 2 mm are investigated. In the vertical air stream of the wind tunnel droplets with diameter of 700 micron are freely floated at their terminal velocities, simulating the flow conditions of the free atmosphere. Furthermore, the wind tunnel offers a unique platform for contact freezing experiments. Supercooled water droplets are floated in the vertical air stream at their terminal velocities and INP are injected into the tunnel air stream upstream of them. As soon as INP collides with the supercooled droplet the contact freezing is initiated. The first results of immersion and contact freezing experiments with cellulose particles both in the acoustic levitator and in the wind tunnel will be presented. Cellulose is considered as typical INP of biological origin and a macrotracer for plant debris. Nucleating properties of cellulose will be provided, mainly focusing on the temperature, INP concentration, and specific surface area dependences of the freezing processes. Direct comparison between the different experimental techniques (acoustic levitator and wind tunnel), as well as between nucleation modes (immersion and contact freezing) will be presented. The work is carried out within the framework of the German research unit INUIT.

  3. Reverberation cancellation in a closed test section of a wind tunnel using a multi-microphone cesptral method

    NASA Astrophysics Data System (ADS)

    Blacodon, D.; Bulté, J.

    2014-04-01

    Nowadays, although aerodynamic data are still primarily sought after during wind tunnel tests, reliable acoustic measurements also become a priority for aircraft designers. In order to gather both kinds of data, aerodynamic and acoustic tests are carried out simultaneously under the same closed test section. This solution has two major drawbacks: the acoustic signals delivered by microphones may be corrupted by the boundary layer expanding on the wind tunnel walls and by the reverberant noise originating from reflective surfaces. Technological solutions can be deployed to reduce the corruption of the signals by the wind tunnel background noise. Methods based on the power cepstrum can be used to reduce reverberation effects by removing the quefrencies due to the echoes in the cepstral domain.

  4. Supersonic Flow Choking in Engine Wind Tunnels

    NASA Astrophysics Data System (ADS)

    Mitani, Tohru; Miyajima, Hiroshi; Tani, Koichiro; Kouchi, Toshinori; Sakuranaka, Noboru; Watanabe, Syuichi

    Breakdown of diffuser flow was often observed in our scramjet engine tests. This facility operation may damage the engine wind-tunnel and should be prevented. An one-dimensional analysis was applied to the diffuser flow to identify the causes of the flow breakdown. All the losses and gains by engine and friction loss in the diffuser were represented by point-sources of mass, momentum and energy. The thermal choking condition was calculated by uses of a chemical equilibrium code. The fuel rates causing the flow-choking successfully reproduced the limit fuel rates observed in our tests. Inlet-unstart of engine lost the ejector-pumping effect in the diffuser system to trigger the flow choking. The choking was also promoted by the drag of the gas sampling rakes. The choking in diffuser flow and the engine unstart may couple each other to cause hysteresis in the diffuser breakdown, which was also experienced in our tests. A rocket-based, combined-cycle (RBCC) engine will be tested under the Mach 4 condition. The engine easily causes the choking of diffuser because of the large propellant supply rates and the relatively-low specific impulse. Operation of the wind-tunnel was discussed to control the flow choking in the tests.

  5. Hyper-X Wind Tunnel Program

    NASA Technical Reports Server (NTRS)

    McClinton, C. R.; Holland, S. D.; Rock, K. E.; Engelund, W. C.; Voland, R. T.; Huebner, L. D.; Roger, R. C.

    1998-01-01

    This paper provides an overview of NASA's focused hypersonic technology program, called the Hyper-X Program. The Hyper-X Program, a joint NASA Langley and Dryden program, is designed to move hypersonic, air breathing vehicle technology from the laboratory environment to the flight environment, the last stage preceding prototype development. The Hyper-X research vehicle will provide the first ever opportunity to obtain data on an airframe integrated scramjet (supersonic combustion ramjet) propulsion system at true flight conditions and the first opportunity for flight validation of experimental wind tunnel, numerical and analytical methods used for design of these vehicles. A substantial portion of the program is experimentally based, both for database development and performance validation. The program is now concentrating on Mach 7 vehicle development, verification and validation and flight test risk reduction. This paper concentrates on the aerodynamic and propulsion experimental programs. Wind tunnel testing of the flight engine and complete airframe integrated scramjet configuration flow-path is expected in 1998 and 1999, respectively, and flight test is planned for 2000.

  6. Wind Tunnel Seeding Systems for Laser Velocimeters

    NASA Technical Reports Server (NTRS)

    Hunter, W. W., Jr. (Compiler); Nichols, C. E., Jr. (Compiler)

    1985-01-01

    The principal motivating factor for convening the Workshop on the Development and Application of Wind Tunnel Seeding Systems for Laser Velocimeters is the necessity to achieve efficient operation and, most importantly, to insure accurate measurements with velocimeter techniques. The ultimate accuracy of particle scattering based laser velocimeter measurements of wind tunnel flow fields depends on the ability of the scattering particle to faithfully track the local flow field in which it is embedded. A complex relationship exists between the particle motion and the local flow field. This relationship is dependent on particle size, size distribution, shape, and density. To quantify the accuracy of the velocimeter measurements of the flow field, the researcher has to know the scattering particle characteristics. In order to obtain optimum velocimeter measurements, the researcher is striving to achieve control of the particle characteristics and to verify those characteristics at the measurement point. Additionally, the researcher is attempting to achieve maximum measurement efficiency through control of particle concentration and location in the flow field.

  7. Wind tunnel studies of Martian aeolian processes

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Iversen, J. D.; Pollack, J. B.; Udovich, N.; White, B.

    1973-01-01

    Preliminary results are reported of an investigation which involves wind tunnel simulations, geologic field studies, theoretical model studies, and analyses of Mariner 9 imagery. Threshold speed experiments were conducted for particles ranging in specific gravity from 1.3 to 11.35 and diameter from 10.2 micron to 1290 micron to verify and better define Bagnold's (1941) expressions for grain movement, particularly for low particle Reynolds numbers and to study the effects of aerodynamic lift and surface roughness. Wind tunnel simulations were conducted to determine the flow field over raised rim craters and associated zones of deposition and erosion. A horseshoe vortex forms around the crater, resulting in two axial velocity maxima in the lee of the crater which cause a zone of preferential erosion in the wake of the crater. Reverse flow direction occurs on the floor of the crater. The result is a distinct pattern of erosion and deposition which is similar to some martian craters and which indicates that some dark zones around Martian craters are erosional and some light zones are depositional.

  8. High speed wind tunnel tests of the PTA aircraft. [Propfan Test Assessment Program

    NASA Technical Reports Server (NTRS)

    Aljabri, A. S.; Little, B. H., Jr.

    1986-01-01

    Propfans, advanced highly-loaded propellers, are proposed to power transport aircraft that cruise at high subsonic speeds, giving significant fuel savings over the equivalent turbofan-powered aircraft. NASA is currently sponsoring the Propfan Test Assessment Program (PTA) to provide basic data on the structural integrity and acoustic performance of the propfan. The program involves installation design, wind-tunnel tests, and flight tests of the Hamilton Standard SR-7 propfan in a wing-mount tractor installation on the Gulfstream II aircraft. This paper reports on the high-speed wind-tunnel tests and presents the computational aerodynamic methods that were employed in the analyses, design, and evaluation of the configuration. In spite of the complexity of the configuration, these methods provide aerodynamic predictions which are in excellent agreement with wind-tunnel data.

  9. Hypersonic Wind Tunnels: Latest Citations from the Aerospace Database

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The bibliography contains citations concerning the design, construction, operation, performance, and use of hypersonic wind tunnels. References cover the design of flow nozzles, diffusers, test sections, and ejectors for tunnels driven by compressed air, high-pressure gases, or cryogenic liquids. Methods for flow calibration, boundary layer control, local and freestream turbulence reduction, and force measurement are discussed. Intrusive and non-intrusive instrumentation, sources of measurement error, and measurement corrections are also covered. The citations also include the testing of inlets, nozzles, airfoils, and other components of hypersonic aerospace vehicles. Comprehensive coverage of supersonic and blowdown wind tunnels, and force balance systems for wind tunnels are covered in separate bibliographies.

  10. Screens Would Protect Wind-Tunnel Fan Blades

    NASA Technical Reports Server (NTRS)

    Farmer, Moses G.

    1992-01-01

    Butterfly screen installed in wind tunnel between test section and fan blades to prevent debris from reaching fan blades if model structure fails. Protective screens deployed manually or automatically. Concept beneficial anywhere wind tunnels employed. Also useful in areas outside of aerospace industry, such as in airflow design of automobiles and other vehicles.

  11. Build an Inexpensive Wind Tunnel to Test CO2 Cars

    ERIC Educational Resources Information Center

    McCormick, Kevin

    2012-01-01

    As part of the technology education curriculum, the author's eighth-grade students design, build, test, and race CO2 vehicles. To help them in refining their designs, they use a wind tunnel to test for aerodynamic drag. In this article, the author describes how to build a wind tunnel using inexpensive, readily available materials. (Contains 1…

  12. Weather hazard simulation in the Modane wind-tunnels

    NASA Technical Reports Server (NTRS)

    Fasso, G.; Leclere, G.; Charpin, F.

    1983-01-01

    Specially designed wind tunnel setups make it possible to simulate various weather hazards, in an imperfect but systematic manner. Systems installed in the Modane wind tunnels for rain and icing tests are described. A qust simulator being developed is also discussed.

  13. Jet engine powers large, high-temperature wind tunnel

    NASA Technical Reports Server (NTRS)

    Benham, T. F.; Mulliken, S. R.

    1967-01-01

    Wind tunnel for large component testing uses a jet engine with afterburner to provide high temperatures /1200 degrees to 2000 degrees F/ and controlled high velocity gas. This economical wind tunnel can accommodate parts ten feet by ten feet or larger, and is a useful technique for qualitative information.

  14. 5. VIEW NORTH OF TEST SECTION IN FULLSCALE WIND TUNNEL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. VIEW NORTH OF TEST SECTION IN FULL-SCALE WIND TUNNEL WITH FREE-FLIGHT MODEL OF A BOEING 737 SUSPENDED FROM A SAFETY CABLE. - NASA Langley Research Center, Full-Scale Wind Tunnel, 224 Hunting Avenue, Hampton, Hampton, VA

  15. Digital control of wind tunnel magnetic suspension and balance systems

    NASA Technical Reports Server (NTRS)

    Britcher, Colin P.; Goodyer, Michael J.; Eskins, Jonathan; Parker, David; Halford, Robert J.

    1987-01-01

    Digital controllers are being developed for wind tunnel magnetic suspension and balance systems, which in turn permit wind tunnel testing of aircraft models free from support interference. Hardware and software features of two existing digital control systems are reviewed. Some aspects of model position sensing and system calibration are also discussed.

  16. 14. EXTERIOR VIEW OF OLD TENFOOT WIND TUNNEL (1991). ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. EXTERIOR VIEW OF OLD TEN-FOOT WIND TUNNEL (1991). - Wright-Patterson Air Force Base, Area B, Buildings 25 & 24,10-foot & 20-foot Wind Tunnel Complex, Northeast side of block bounded by K, G, Third, & Fifth Streets, Dayton, Montgomery County, OH

  17. 13. EXTERIOR VIEW OF OLD TENFOOT WIND TUNNEL (1991). ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. EXTERIOR VIEW OF OLD TEN-FOOT WIND TUNNEL (1991). - Wright-Patterson Air Force Base, Area B, Buildings 25 & 24,10-foot & 20-foot Wind Tunnel Complex, Northeast side of block bounded by K, G, Third, & Fifth Streets, Dayton, Montgomery County, OH

  18. Videogrammetric Model Deformation Measurement Technique for Wind Tunnel Applications

    NASA Technical Reports Server (NTRS)

    Barrows, Danny A.

    2006-01-01

    Videogrammetric measurement technique developments at NASA Langley were driven largely by the need to quantify model deformation at the National Transonic Facility (NTF). This paper summarizes recent wind tunnel applications and issues at the NTF and other NASA Langley facilities including the Transonic Dynamics Tunnel, 31-Inch Mach 10 Tunnel, 8-Ft high Temperature Tunnel, and the 20-Ft Vertical Spin Tunnel. In addition, several adaptations of wind tunnel techniques to non-wind tunnel applications are summarized. These applications include wing deformation measurements on vehicles in flight, determining aerodynamic loads based on optical elastic deformation measurements, measurements on ultra-lightweight and inflatable space structures, and the use of an object-to-image plane scaling technique to support NASA s Space Exploration program.

  19. A Vision in Aeronautics: The K-12 Wind Tunnel Project

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A Vision in Aeronautics, a project within the NASA Lewis Research Center's Information Infrastructure Technologies and Applications (IITA) K-12 Program, employs small-scale, subsonic wind tunnels to inspire students to explore the world of aeronautics and computers. Recently, two educational K-12 wind tunnels were built in the Cleveland area. During the 1995-1996 school year, preliminary testing occurred in both tunnels.

  20. Initial Assessment of Acoustic Source Visibility with a 24-Element Microphone Array in the Arnold Engineering Development Center 80- by 120-Foot Wind Tunnel at NASA Ames Research Center

    NASA Technical Reports Server (NTRS)

    Horne, William C.

    2011-01-01

    Measurements of background noise were recently obtained with a 24-element phased microphone array in the test section of the Arnold Engineering Development Center 80- by120-Foot Wind Tunnel at speeds of 50 to 100 knots (27.5 to 51.4 m/s). The array was mounted in an aerodynamic fairing positioned with array center 1.2m from the floor and 16 m from the tunnel centerline, The array plate was mounted flush with the fairing surface as well as recessed in. (1.27 cm) behind a porous Kevlar screen. Wind-off speaker measurements were also acquired every 15 on a 10 m semicircular arc to assess directional resolution of the array with various processing algorithms, and to estimate minimum detectable source strengths for future wind tunnel aeroacoustic studies. The dominant background noise of the facility is from the six drive fans downstream of the test section and first set of turning vanes. Directional array response and processing methods such as background-noise cross-spectral-matrix subtraction suggest that sources 10-15 dB weaker than the background can be detected.

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

    NASA Technical Reports Server (NTRS)

    Kmak, Frank J.

    2000-01-01

    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.

  2. Effect of the mode composition disturbances in a high-enthalpy wind tunnel on wave processes in the hypersonic viscous shock layer

    NASA Astrophysics Data System (ADS)

    Kirilovskiy, S. V.; Poplavskaya, T. V.; Tsyryulnikov, I. S.

    2016-06-01

    A numerical and experimental study of the spectral distribution of disturbances hotshot wind tunnel was performed. It was found that disturbances are the superposition of fast acoustic waves propagating along axial direction and oblique slow acoustic waves which have less amplitude. Numerical simulation of disturbances evolution in the nozzle of the wind tunnel was carried out by solving 2D Navier-Stokes equations using the ANSYS Fluent program package. Experiments were carried out in the IT-302M high-enthalpy hotshot wind tunnel ITAM SB RAS.

  3. Cryogenic wind tunnel activities at the University of Southampton. [flow visusalization technique for low speed wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Goodyer, M. J.

    1979-01-01

    The characteristics and behavior of a 0.3m transonic cryogenic wind tunnel are discussed. The wide band of usable Reynolds numbers is analyzed along with a flow visualization technique using propane. The combination of magnetic suspension with the cryogenic wind tunnel is described. An outline of the circuit showing the locations of the magnet system and the features of the tunnel are presented.

  4. Overview of 6- X 6-foot wind tunnel aero-optics tests. [transonic wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Buell, D. A.

    1980-01-01

    The splitter-plate arrangement used in tests in the 6 x 6 foot wind tunnel and how it was configured to study boundary layers, both heated and unheated, shear layers over a cavity, separated flows behind spoilers, accelerated flows around a turret, and a turret wake are described. The flows are characterized by examples of the steady-state pressure and of velocity profiles through the various types of flow layers.

  5. Wind tunnel force and pressure tests

    NASA Technical Reports Server (NTRS)

    Wentz, W. H., Jr.

    1981-01-01

    Force and surface pressure distributions were measured for a 13% medium speed (NASA MS(1)-0313) airfoil fitted with 20% aileron, 25% slotted flap and 10% slot lip spoiler. All tests were conducted in the Walter Beech Memorial Wind Tunnel at a Reynolds number of 2.2 million and a Mach number of 0.13. Results include lift, drag, pitching moments, control surface normal force and hinge moments, and surface pressure distributions. The basic airfoil exhibits low speed characteristics similar to the GA(W)-2 airfoil. Incremental aileron and spoiler performance are quite comparable to that obtained on the GA(W)-2 airfoil. Slotted flap performance on this section is reduced compared to the GA(W)-2, resulting in a highest c sub l max of 3.00 compared to 3.35 for the GA(W)-2.

  6. Wind tunnel modeling of heavy gas dispersion

    NASA Astrophysics Data System (ADS)

    König-Langlo, G.; Schatzmann, M.

    Assessment of risk attending the manufacturing, storing and transportation of flammable and toxic gases involves the quantification of the ensuing dispersion in case of an accidental release. Worst case considerations have to be applied in order to obtain conservative estimates The paper describes a method for the determination of lower flammability distances for gases heavier than air under unfavorable atmospheric conditions. The method is based on the results of a wind tunnel study investigating the dispersion of instantaneous as well as continuous releases into a boundary-layer shear flow disturbed and undisturbed by surface obstacles. Thermodynamic effects on the dispersing cloud have been taken into account through modification of source parameters. The results have been compared with those from corresponding field trials. The agreement is generally fair. The method has now been converted into a detailed guideline for dispersion calculations within risk assessment studies for flammable and toxic heavy gases (VDI 3783, Part 2, Beuth Verlag, Berlin, 1990).

  7. Advanced recovery systems wind tunnel test report

    NASA Technical Reports Server (NTRS)

    Geiger, R. H.; Wailes, W. K.

    1990-01-01

    Pioneer Aerospace Corporation (PAC) conducted parafoil wind tunnel testing in the NASA-Ames 80 by 120 test sections of the National Full-Scale Aerodynamic Complex, Moffett Field, CA. The investigation was conducted to determine the aerodynamic characteristics of two scale ram air wings in support of air drop testing and full scale development of Advanced Recovery Systems for the Next Generation Space Transportation System. Two models were tested during this investigation. Both the primary test article, a 1/9 geometric scale model with wing area of 1200 square feet and secondary test article, a 1/36 geometric scale model with wing area of 300 square feet, had an aspect ratio of 3. The test results show that both models were statically stable about a model reference point at angles of attack from 2 to 10 degrees. The maximum lift-drag ratio varied between 2.9 and 2.4 for increasing wing loading.

  8. NASA Glenn Wind Tunnel Model Systems Criteria

    NASA Technical Reports Server (NTRS)

    Soeder, Ronald H.; Roeder, James W.; Stark, David E.; Linne, Alan A.

    2004-01-01

    This report describes criteria for the design, analysis, quality assurance, and documentation of models that are to be tested in the wind tunnel facilities at the NASA Glenn Research Center. This report presents two methods for computing model allowable stresses on the basis of the yield stress or ultimate stress, and it defines project procedures to test models in the NASA Glenn aeropropulsion facilities. Both customer-furnished and in-house model systems are discussed. The functions of the facility personnel and customers are defined. The format for the pretest meetings, safety permit process, and model reviews are outlined. The format for the model systems report (a requirement for each model that is to be tested at NASA Glenn) is described, the engineers responsible for developing the model systems report are listed, and the timetable for its delivery to the project engineer is given.

  9. 7 x 10-Foot Atmospheric Wind Tunnel (AWT)

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Engineer is shown adjusting a test model of the Clark-Y airfoil #1 in 7 x 10-Foot Atmospheric Wind Tunnel (AWT). In 1928, the NACA decided to replace its original Atmospheric Wind Tunnel (AWT #1) with two tunnels--the 5-foot vertical tunnel and a 7 by 10 foot rectangular throat tunnel. Both were open-throat, closed-return-passage tunnels and were housed in the same building the first wind tunnel had been located in. While the 5-foot vertical tunnel was to be used mainly for spin tests, the 7x10 was an all-purpose tunnel although the main intent was to study stability and control problems. Construction was completed in the summer of 1930; calibration later that same year. The balance was installed and the tunnel went into operation in early 1931. The test model used to study the coefficients of lift, drag, cross-wind force, and pitching moment was a 'Clark Y airfoil with a 10-inch chord and a 60-inch span, and the model was set at 20 positive yaw.'

  10. Acoustic emission monitoring of wind turbine blades

    NASA Astrophysics Data System (ADS)

    Van Dam, Jeremy; Bond, Leonard J.

    2015-03-01

    Damage to wind turbine blades can, if left uncorrected, evolve into catastrophic failures resulting in high costs and significant losses for the operator. Detection of damage, especially in real time, has the potential to mitigate the losses associated with such catastrophic failure. To address this need various forms of online monitoring are being investigated, including acoustic emission detection. In this paper, pencil lead breaks are used as a standard reference source and tests are performed on unidirectional glass-fiber-reinforced-polymer plates. The mechanical pencil break is used to simulate an acoustic emission (AE) that generates elastic waves in the plate. Piezoelectric sensors and a data acquisition system are used to detect and record the signals. The expected dispersion curves generated for Lamb waves in plates are calculated, and the Gabor wavelet transform is used to provide dispersion curves based on experimental data. AE sources using an aluminum plate are used as a reference case for the experimental system and data processing validation. The analysis of the composite material provides information concerning the wave speed, modes, and attenuation of the waveform, which can be used to estimate maximum AE event - receiver separation, in a particular geometry and materials combination. The foundational data provided in this paper help to guide improvements in online structural health monitoring of wind turbine blades using acoustic emission.

  11. Status and capabilities of the National Full Scale Facility 40- by 80-foot wind tunnel modification

    NASA Technical Reports Server (NTRS)

    Mort, K. W.; Engelbert, D. F.; Dusterberry, J. C.

    1982-01-01

    The background, requirements, and aerodynamic design of the modified NASA Ames 40 x 80 ft wind tunnel are reviewed, along with the systems integration and systems test results. Advancing vehicle sizes and airspeeds required a larger wind tunnel test section and a capability for 100 and 300 knots airspeed simulation. Acoustic mufflers at the inlet and exit of the nonreturn circuit provide noise suppression. The enlarged test section is intended to accomodate the complex flowfields of wings with high lift coefficients, and the drive system is designed with minimum residual swirl. Features of the fan blades are examined, along with characteristics of the test channels, control vanes and louvers, the exit, circuit losses, temperature rises during operation of the nonreturn circuit, and the facility acoustics. Specific construction problems and solutions for the conversion process are outlined, and it is noted that operational status is expected at the end of 1982.

  12. Computational design and analysis of flatback airfoil wind tunnel experiment.

    SciTech Connect

    Mayda, Edward A.; van Dam, C.P.; Chao, David D.; Berg, Dale E.

    2008-03-01

    A computational fluid dynamics study of thick wind turbine section shapes in the test section of the UC Davis wind tunnel at a chord Reynolds number of one million is presented. The goals of this study are to validate standard wind tunnel wall corrections for high solid blockage conditions and to reaffirm the favorable effect of a blunt trailing edge or flatback on the performance characteristics of a representative thick airfoil shape prior to building the wind tunnel models and conducting the experiment. The numerical simulations prove the standard wind tunnel corrections to be largely valid for the proposed test of 40% maximum thickness to chord ratio airfoils at a solid blockage ratio of 10%. Comparison of the computed lift characteristics of a sharp trailing edge baseline airfoil and derived flatback airfoils reaffirms the earlier observed trend of reduced sensitivity to surface contamination with increasing trailing edge thickness.

  13. Combined Experiment Phase 1. [Horizontal axis wind turbines: wind tunnel testing versus field testing

    SciTech Connect

    Butterfield, C.P.; Musial, W.P.; Simms, D.A.

    1992-10-01

    How does wind tunnel airfoil data differ from the airfoil performance on an operating horizontal axis wind turbine (HAWT) The National Renewable Energy laboratory has been conducting a comprehensive test program focused on answering this question and understanding the basic fluid mechanics of rotating HAWT stall aerodynamics. The basic approach was to instrument a wind rotor, using an airfoil that was well documented by wind tunnel tests, and measure operating pressure distributions on the rotating blade. Based an the integrated values of the pressure data, airfoil performance coefficients were obtained, and comparisons were made between the rotating data and the wind tunnel data. Care was taken to the aerodynamic and geometric differences between the rotating and the wind tunnel models. This is the first of two reports describing the Combined Experiment Program and its results. This Phase I report covers background information such as test setup and instrumentation. It also includes wind tunnel test results and roughness testing.

  14. Hardening Doppler Global Velocimetry Systems for Large Wind Tunnel Applications

    NASA Technical Reports Server (NTRS)

    Meyers, James F.; Lee, Joseph W.; Fletcher, Mark T.; South, Bruce W.

    2004-01-01

    The development of Doppler Global Velocimetry from a laboratory curiosity to a wind tunnel instrumentation system is discussed. This development includes system advancements from a single velocity component to simultaneous three components, and from a steady state to instantaneous measurement. Improvements to system control and stability are discussed along with solutions to real world problems encountered in the wind tunnel. This on-going development program follows the cyclic evolution of understanding the physics of the technology, development of solutions, laboratory and wind tunnel testing, and reevaluation of the physics based on the test results.

  15. Wind Tunnel Management and Resource Optimization: A Systems Modeling Approach

    NASA Technical Reports Server (NTRS)

    Jacobs, Derya, A.; Aasen, Curtis A.

    2000-01-01

    Time, money, and, personnel are becoming increasingly scarce resources within government agencies due to a reduction in funding and the desire to demonstrate responsible economic efficiency. The ability of an organization to plan and schedule resources effectively can provide the necessary leverage to improve productivity, provide continuous support to all projects, and insure flexibility in a rapidly changing environment. Without adequate internal controls the organization is forced to rely on external support, waste precious resources, and risk an inefficient response to change. Management systems must be developed and applied that strive to maximize the utility of existing resources in order to achieve the goal of "faster, cheaper, better". An area of concern within NASA Langley Research Center was the scheduling, planning, and resource management of the Wind Tunnel Enterprise operations. Nine wind tunnels make up the Enterprise. Prior to this research, these wind tunnel groups did not employ a rigorous or standardized management planning system. In addition, each wind tunnel unit operated from a position of autonomy, with little coordination of clients, resources, or project control. For operating and planning purposes, each wind tunnel operating unit must balance inputs from a variety of sources. Although each unit is managed by individual Facility Operations groups, other stakeholders influence wind tunnel operations. These groups include, for example, the various researchers and clients who use the facility, the Facility System Engineering Division (FSED) tasked with wind tunnel repair and upgrade, the Langley Research Center (LaRC) Fabrication (FAB) group which fabricates repair parts and provides test model upkeep, the NASA and LARC Strategic Plans, and unscheduled use of the facilities by important clients. Expanding these influences horizontally through nine wind tunnel operations and vertically along the NASA management structure greatly increases the

  16. Unified Instrumentation: Examining the Simultaneous Application of Advanced Measurement Techniques for Increased Wind Tunnel Testing Capability

    NASA Technical Reports Server (NTRS)

    Fleming, Gary A. (Editor); Bartram, Scott M.; Humphreys, William M., Jr.; Jenkins, Luther N.; Jordan, Jeffrey D.; Lee, Joseph W.; Leighty, Bradley D.; Meyers, James F.; South, Bruce W.; Cavone, Angelo A.; Ingram, JoAnne L.

    2002-01-01

    A Unified Instrumentation Test examining the combined application of Pressure Sensitive Paint, Projection Moire Interferometry, Digital Particle Image Velocimetry, Doppler Global Velocimetry, and Acoustic Microphone Array has been conducted at the NASA Langley Research Center. The fundamental purposes of conducting the test were to: (a) identify and solve compatibility issues among the techniques that would inhibit their simultaneous application in a wind tunnel, and (b) demonstrate that simultaneous use of advanced instrumentation techniques is feasible for increasing tunnel efficiency and identifying control surface actuation / aerodynamic reaction phenomena. This paper provides summary descriptions of each measurement technique used during the Unified Instrumentation Test, their implementation for testing in a unified fashion, and example results identifying areas of instrument compatibility and incompatibility. Conclusions are drawn regarding the conditions under which the measurement techniques can be operated simultaneously on a non-interference basis. Finally, areas requiring improvement for successfully applying unified instrumentation in future wind tunnel tests are addressed.

  17. Wind Tunnel to Atmospheric Mapping for Static Aeroelastic Scaling

    NASA Technical Reports Server (NTRS)

    Heeg, Jennifer; Spain, Charles V.; Rivera, J. A.

    2004-01-01

    Wind tunnel to Atmospheric Mapping (WAM) is a methodology for scaling and testing a static aeroelastic wind tunnel model. The WAM procedure employs scaling laws to define a wind tunnel model and wind tunnel test points such that the static aeroelastic flight test data and wind tunnel data will be correlated throughout the test envelopes. This methodology extends the notion that a single test condition - combination of Mach number and dynamic pressure - can be matched by wind tunnel data. The primary requirements for affecting this extension are matching flight Mach numbers, maintaining a constant dynamic pressure scale factor and setting the dynamic pressure scale factor in accordance with the stiffness scale factor. The scaling is enabled by capabilities of the NASA Langley Transonic Dynamics Tunnel (TDT) and by relaxation of scaling requirements present in the dynamic problem that are not critical to the static aeroelastic problem. The methodology is exercised in two example scaling problems: an arbitrarily scaled wing and a practical application to the scaling of the Active Aeroelastic Wing flight vehicle for testing in the TDT.

  18. The Influence of Wind-Tunnel Walls on Discrete Frequency Noise

    NASA Astrophysics Data System (ADS)

    Mosher, Marianne

    Enclosures, partial or complete, significantly affect the sound field of a source contained in the enclosure. In particular, wind-tunnel walls effect measurements of the sound field of an aircraft model thereby complicating noise measurements of aircraft in wind tunnels. This work examines the effect of the wind tunnel on sound fields. The acoustic field from a known source in a wind tunnel has been modeled as an acoustic source in uniform subsonic flow, in an infinitely long duct with constant cross-section. The acoustic impedance boundary condition at the wall allows sound absorption. The problem of an aeroacoustic source in a duct is formulated as an inhomogeneous integro-differential equation for the acoustic pressure on the duct surface. The domain is divided into a near field, extending about one duct diameter from the source, and a far field. This model is solved with a numerical panel technique in the near field and matched to an outer analytic solution in the far field. Several sample programs are studied in a rectangular duct with and without flow. A simple model problem, for which an analytic approximation exists, demonstrates that the numerical calculation correctly solves the numerical model. The acoustic fields for many simple sources are examined. The acoustic field from a simple model of helicopter noise is studied in the duct. Results show that the presence of the duct significantly changes the acoustic field. For a given source, the region in the duct near the source resembling the free field increases as the wall absorption increases. Outside this near field the sound depends mostly on the product of source wave number with duct cross dimension. Low subsonic flow (Mach number less than about 0.2) has little effect on the sound pressure level for most cases. Small changes in any parameter when the frequency is near a resonance, can change the outer acoustic field significantly. For low frequency rotor harmonic noise, the sound levels beyond one

  19. SAMPSON smart inlet design overview and wind tunnel test: II. Wind tunnel test

    NASA Astrophysics Data System (ADS)

    Pitt, Dale M.; Dunne, James P.; White, Edward V.

    2002-07-01

    The Smart Aircraft and Marine System Projects Demonstration (SAMPSON) program was a DARPA funded effort conducted by the Boeing Company, General Dynamics - Electric Boat Division, and the Pennsylvania State University. NASA Langley Research Center (NASA LaRC) was technical monitor for the aircraft demonstration, while the Navy's Office of Naval Research (ONR) was technical monitor for the marine demonstration. Dr. Ephrahim Garcia, DARPA/DSO, acted as the DARPA program manager for SAMPSON. The SAMPSON program objectives were to demonstrate smart structures based systems on large/full scale structures in realistic environments. The SAMPSON aircraft demonstration was the wind tunnel testing of a full scale F-15 aircraft inlet that was capable of in-flight structural variations accomplished using smart materials, called the 'SAMPSON Smart Inlet'. The SAMPSON Smart Inlet was removed from an F-15E airframe and structurally modified to interface with the NASA LaRC 16-Foot Transonic Tunnel model support system. This is Part II of two works documenting the SAMPSON Smart Inlet design and testing. A discussion of the two wind tunnel tests will be presented here in Part II. The design of the shape changing components of the Smart Inlet is presented in a separate work, Part I.

  20. Procedures and requirements for testing in the Langley Research Center unitary plan wind tunnel

    NASA Technical Reports Server (NTRS)

    Wassum, Donald L.; Hyman, Curtis E., Jr.

    1988-01-01

    Information is presented to assist those interested in conducting wind-tunnel testing within the Langley Unitary Plan Wind Tunnel. Procedures, requirements, forms and examples necessary for tunnel entry are included.

  1. A simplified method for calculating temperature time histories in cryogenic wind tunnels

    NASA Technical Reports Server (NTRS)

    Stallings, R. L., Jr.; Lamb, M.

    1976-01-01

    Average temperature time history calculations of the test media and tunnel walls for cryogenic wind tunnels have been developed. Results are in general agreement with limited preliminary experimental measurements obtained in a 13.5-inch pilot cryogenic wind tunnel.

  2. Wind tunnel interference factors for high-lift wings in closed wind tunnels. Ph.D. Thesis - Princeton Univ.

    NASA Technical Reports Server (NTRS)

    Joppa, R. G.

    1973-01-01

    A problem associated with the wind tunnel testing of very slow flying aircraft is the correction of observed pitching moments to free air conditions. The most significant effects of such corrections are to be found at moderate downwash angles typical of the landing approach. The wind tunnel walls induce interference velocities at the tail different from those induced at the wing, and these induced velocities also alter the trajectory of the trailing vortex system. The relocated vortex system induces different velocities at the tail from those experienced in free air. The effect of the relocated vortex and the walls is to cause important changes in the measured pitching moments in the wind tunnel.

  3. Kasprzyk airfoil. The first wind-tunnel tests

    NASA Technical Reports Server (NTRS)

    Wusatowski, T.

    1984-01-01

    The Kasprzyk slotted flap glider airfoil (the Kasper wing) enabling glider flight at 32 km/h and 0.5 m/sec descent speed was wind tunnel tested in the U.S. The test layout is described and reasons offered for discrepancies between wind tunnel results and Polish in flight data: high induced drag caused by relative size of model wing span and tunnel, by vortex attenuators on the model and their proximity to the tunnel wall, nonsimilarity between flow over a smooth wing and flow over the Kasprzyk wing with bound vortices, obstruction of the tunnel test chamber cross section by the model wing, discrepant Reynolds numbers, and model airfoil aspect ratio much smaller than the prototype. The overall results offer partial confirmation of the Kasprzyk theory, but further in tunnel and in flight studies are recommended.

  4. Numerically Controlled Machining Of Wind-Tunnel Models

    NASA Technical Reports Server (NTRS)

    Kovtun, John B.

    1990-01-01

    New procedure for dynamic models and parts for wind-tunnel tests or radio-controlled flight tests constructed. Involves use of single-phase numerical control (NC) technique to produce highly-accurate, symmetrical models in less time.

  5. Low-Hysteresis Flow-Through Wind-Tunnel Balance

    NASA Technical Reports Server (NTRS)

    Kunz, N.; Luna, P. M.; Roberts, A. C.; Smith, R. C.; Horne, W. L.; Smith, K. M.

    1992-01-01

    Improved flow-through wind-tunnel balance includes features minimizing both spurious force readings caused by internal pressurized flow and mechanical hysteresis. Symmetrical forces caused by internal flow cancelled.

  6. The future of wind tunnel technology in Germany

    NASA Technical Reports Server (NTRS)

    Ewald, B.

    1978-01-01

    The practical value of a wind tunnel which is not dependent solely on size or achievable Reynolds number was examined. Measurement, interpretative and evaluative procedures developed in small facilities were also studied.

  7. Continuous-flow variable-density wind tunnel facilities

    NASA Technical Reports Server (NTRS)

    Herrera, J. G.

    1972-01-01

    Unique features of wind tunnel facilities at Jet Propulsion Laboratory permit variety of conventional and novel tests to be performed at supersonic and hypersonic speeds. Facilities and operations are described.

  8. Space shuttle phase B wind tunnel test database

    NASA Technical Reports Server (NTRS)

    Glynn, J. L.; Poucher, D. E.

    1988-01-01

    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 were acquired by competing contractors and NASA centers for an extensive variety of configurations with an array of wing and body planforms. This wind tunnel test data has 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, retro-glide and twin body. Orbiter configuration types include straight and delta wings, lifting body, drop tanks and double delta wings.

  9. A wind tunnel bioassay system for screening mosquito repellents.

    PubMed

    Sharpington, P J; Healy, T P; Copland, M J

    2000-09-01

    A wind tunnel bioassay system to screen mosquito repellents is described. A wind tunnel is utilized to exploit the upwind flight response of host-seeking mosquitoes. Mosquitoes within the wind tunnel are activated with human breath, fly upwind, and land on heated chick skins. This behavioral sequence results in a consistently high percentage of the test population approaching repellent or control stimuli. The bioassay system is calibrated with diethyl methylbenzamide against Aedes aegypti and demonstrates a reproducible dose-response relationship. The persistence of diethyl methyl benzamide after a 1-h period is also recorded. The design of the bioassay system permits simultaneous, independent testing of 3 candidate repellents. The wind tunnel bioassay system is compared to other techniques for evaluating mosquito repellents. PMID:11081652

  10. 7. Detail view west of Arctic Chamber wind tunnel shell ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Detail view west of Arctic Chamber wind tunnel shell (typical) in east elevation. - Natick Research & Development Laboratories, Climatic Chambers Building, U.S. Army Natick Research, Development & Engineering Center (NRDEC), Natick, Middlesex County, MA

  11. 14. View north of Tropic wind tunnel and frontal view ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. View north of Tropic wind tunnel and frontal view of main fan (typical). - Natick Research & Development Laboratories, Climatic Chambers Building, U.S. Army Natick Research, Development & Engineering Center (NRDEC), Natick, Middlesex County, MA

  12. Oil-smeared models aid wind tunnel measurements

    NASA Technical Reports Server (NTRS)

    Katzoff, S.; Loving, D. K.

    1964-01-01

    For visualizing flow characteristics in wind tunnel tests, model surfaces are smeared with any common petroleum-base oils. These fluoresce under ultraviolet light and the flow patterns are readily visualized.

  13. The 13-inch magnetic suspension and balance system wind tunnel

    NASA Technical Reports Server (NTRS)

    Johnson, William G., Jr.; Dress, David A.

    1989-01-01

    NASA Langley has a small, subsonic wind tunnel in use with the 13-inch Magnetic Suspension and Balance System (MSBS). The tunnel is capable of speeds up to Mach 0.5. This report presents tunnel design and construction details. It includes flow uniformity, angularity, and velocity fluctuation data. It also compares experimental Mach number distribution data with computed results for the General Electric Streamtube Curvature Program.

  14. Comparison of Full-Scale XV-15 Wind Tunnel and In-Flight Blade-Vortex Interaction Noise

    NASA Technical Reports Server (NTRS)

    Kitaplioglu, Cahit; McCluer, M.; Acree, C. W., Jr.; Warmbrodt, William (Technical Monitor)

    1997-01-01

    An isolated full-scale XV-15 rotor was tested in helicopter mode in the NASA Ames 80 by 120-Foot Wind Tunnel. Extensive acoustic data were obtained to define the rotor operating condition for maximum blade-vortex interaction (BVI) noise. Additional data were obtained at operating conditions simulating flight up to 80 knots. An XV-15 aircraft was also tested under operating conditions corresponding to landing approaches for which BVI is expected to be a maximum. In-flight acoustic data were obtained using the YO-3A acoustic research aircraft. An attempt was made to closely match wind tunnel and flight test operating conditions. Details of the two tests are described and some representative acoustic results are presented. Comparisons are shown between the wind tunnel data and corresponding flight test data. Preliminary results indicate very good correlation of the BVI-related features. However, some differences between flight test and wind tunnel results exist away from the BVI event, thought to arise from differences in the two flow environments.

  15. Preliminary Tests in the NACA Free-Spinning Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Zimmerman, C H

    1937-01-01

    Typical models and the testing technique used in the NACA free-spinning wind tunnel are described in detail. The results of tests on two models afford a comparison between the spinning characteristics of scale models in the tunnel and of the airplanes that they represent.

  16. Detection of boundary-layer transitions in wind tunnels

    NASA Technical Reports Server (NTRS)

    Wood, W. R.; Somers, D. M.

    1978-01-01

    Accelerometer replaces stethoscope in technique for detection of laminar-to-turbulent boundary-layer transitions on wind-tunnel models. Technique allows measurements above or below atmospheric pressure because human operator is not required within tunnel. Data may be taken from accelerometer, and pressure transducer simultaneously, and delivered to systems for analysis.

  17. Recent developments in a wind tunnel magnetic balance.

    NASA Technical Reports Server (NTRS)

    Stephens, T.; Covert, E. E.; Vlajinac, M.; Gilliam, G. D.

    1972-01-01

    A functional description of a prototype six component magnetic balance system for wind tunnel application is presented. The relationship of forces and moments on a ferromagnetic body to applied magnetic fields and gradients is shown. The method of producing the required fields in the prototype balance, its magnet arrangement and its performance are discussed. Aerodynamic data obtained with this balance on several model geometries are presented and compared with wind tunnel and ballistic range results.

  18. Initial investigation of cryogenic wind tunnel model filler materials

    NASA Technical Reports Server (NTRS)

    Rush, H. F.; Firth, G. C.

    1985-01-01

    Various filler materials are being investigated for applicability to cryogenic wind tunnel models. The filler materials will be used to fill surface grooves, holes and flaws. The severe test environment of cryogenic models precludes usage of filler materials used on conventional wind tunnel models. Coefficients of thermal expansion, finishing characteristics, adhesion and stability of several candidate filler materials were examined. Promising filler materials are identified.

  19. Laser Velocimetry In Low-Speed Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Orloff, Kenneth L.; Snyder, Philip K.; Reinath, Michael S.

    1990-01-01

    Design and performance of three-dimensional and two-dimensional backscatter laser velocimeter, both used in low-speed wind tunnels, described in report together with historical overview of development of laser velocimetry (LV). Provides measurements of airflow in wind-tunnel tests without perturbing effects of probes and probe-supporting structures. Applicable in such related fields as ventilation engineering and possibly in detection of wing vortexes from large aircraft at airports.

  20. Development of Doppler Global Velocimetry for Wind Tunnel Testing

    NASA Technical Reports Server (NTRS)

    Meyers, James F.

    1994-01-01

    The development of Doppler global velocimetry is described. Emphasis is placed on the modifications necessary to advance this nonintrusive laser based measurement technique from a laboratory prototype to a viable wind tunnel flow diagnostics tool. Several example wind tunnel flow field investigations are described to illustrate the versatility of the technique. Flow conditions ranged from incompressible to Mach 2.8 with measurement distances extending from 1 to 15 m.

  1. Method for Standardizing Sonic-Boom Model Pressure Signatures Measured at Several Wind-Tunnel Facilities

    NASA Technical Reports Server (NTRS)

    Mack, Robert J.

    2007-01-01

    Low-boom model pressure signatures are often measured at two or more wind-tunnel facilities. Preliminary measurements are made at small separation distances in a wind tunnel close at hand, and a second set of pressure signatures is measured at larger separation distances in a wind-tunnel facility with a larger test section. In this report, a method for correcting and standardizing the wind-tunnel-measured pressure signatures obtained in different wind tunnel facilities is presented and discussed.

  2. Wind tunnel seeding particles for laser velocimeter

    NASA Technical Reports Server (NTRS)

    Ghorieshi, Anthony

    1992-01-01

    The design of an optimal air foil has been a major challenge for aerospace industries. The main objective is to reduce the drag force while increasing the lift force in various environmental air conditions. Experimental verification of theoretical and computational results is a crucial part of the analysis because of errors buried in the solutions, due to the assumptions made in theoretical work. Experimental studies are an integral part of a good design procedure; however, empirical data are not always error free due to environmental obstacles or poor execution, etc. The reduction of errors in empirical data is a major challenge in wind tunnel testing. One of the recent advances of particular interest is the use of a non-intrusive measurement technique known as laser velocimetry (LV) which allows for obtaining quantitative flow data without introducing flow disturbing probes. The laser velocimeter technique is based on measurement of scattered light by the particles present in the flow but not the velocity of the flow. Therefore, for an accurate flow velocity measurement with laser velocimeters, two criterion are investigated: (1) how well the particles track the local flow field, and (2) the requirement of light scattering efficiency to obtain signals with the LV. In order to demonstrate the concept of predicting the flow velocity by velocity measurement of particle seeding, the theoretical velocity of the gas flow is computed and compared with experimentally obtained velocity of particle seeding.

  3. Laminar-flow wind tunnel experiments

    NASA Technical Reports Server (NTRS)

    Harvey, William D.; Harris, Charles D.; Sewall, William G.; Stack, John P.

    1989-01-01

    Although most of the laminar flow airfoils recently developed at the NASA Langley Research Center were intended for general aviation applications, low-drag airfoils were designed for transonic speeds and wind tunnel performance tested. The objective was to extend the technology of laminar flow to higher Mach and Reynolds numbers and to swept leading edge wings representative of transport aircraft to achieve lower drag and significantly improved operation costs. This research involves stabilizing the laminar boundary layer through geometric shaping (Natural Laminar Flow, NLF) and active control involving the removal of a portion of the laminar boundary layer (Laminar-Flow Control, LFC), either through discrete slots or perforated surface. Results show that extensive regions of laminar flow with large reductions in skin friction drag can be maintained through the application of passive NLF boundary-layer control technologies to unswept transonic wings. At even greater extent of laminar flow and reduction in the total drag level can be obtained on a swept supercritical airfoil with active boundary layer-control.

  4. Wind tunnel observations of drifting snow

    NASA Astrophysics Data System (ADS)

    Paterna, Enrico; Crivelli, Philip; Lehning, Michael

    2016-04-01

    Drifting snow has a significant impact on snow redistribution in mountains, prairies as well as on glaciers, ice shelves, and sea ice. In all these environments, the local mass balance is highly influenced by drifting snow. Understanding the dynamic of snow saltation is crucial to the accurate description of the process. We applied digital shadowgraphy in a cold wind tunnel to measure drifting snow over natural snow covers. The acquisition and evaluation of time-resolved shadowgraphy images allowed us to resolve a large part of the saltation layer. The technique has been successfully compared to the measurements obtained from a Snow Particle Counter, considered the most robust technique for snow mass-flux measurements so far. The streamwise snow transport is dominated by large-scale events. The vertical snow transport has a more equal distribution of energy across the scales, similarly to what is observed for the flow turbulence velocities. It is hypothesized that the vertical snow transport is a quantity that reflects the local entrainment of the snow crystals into the saltation layer while the streamwise snow transport results from the streamwise development of the trajectories of the snow particles once entrained, and therefore is rather a non-local quantity.

  5. Wind tunnel technology for the development of future commercial aircraft

    NASA Technical Reports Server (NTRS)

    Szodruch, J.

    1986-01-01

    Requirements for new technologies in the area of civil aircraft design are mainly related to the high cost involved in the purchase of modern, fuel saving aircraft. A second important factor is the long term rise in the price of fuel. The demonstration of the benefits of new technologies, as far as these are related to aerodynamics, will,for the foreseeable future, still be based on wind tunnel measurements. Theoretical computation methods are very successfully used in design work, wing optimization, and an estimation of the Reynolds number effect. However, wind tunnel tests are still needed to verify the feasibility of the considered concepts. Along with other costs, the cost for the wind tunnel tests needed for the development of an aircraft is steadily increasing. The present investigation is concerned with the effect of numerical aerodynamics and civil aircraft technology on the development of wind tunnels. Attention is given to the requirements for the wind tunnel, investigative methods, measurement technology, models, and the relation between wind tunnel experiments and theoretical methods.

  6. Full scale subsonic wind tunnel requirements and design studies

    NASA Technical Reports Server (NTRS)

    Kelly, M. W.; Mort, K. W.; Hickey, D. H.

    1972-01-01

    The justification and requirements are summarized for a large subsonic wind tunnel capable of testing full-scale aircraft, rotor systems, and advanced V/STOL aircraft propulsion systems. The design considerations and constraints for such a facility are reviewed, and the trades between facility test capability and costs are discussed. The design studies showed that the structural cost of this facility is the most important cost factor. For this reason (and other considerations such as requirements for engine exhaust gas purging) an open-return wind tunnel having two test sections was selected. The major technical problem in the design of an open-return wind tunnel is maintaining good test section flow quality in the presence of external winds. This problem has been studied extensively, and inlet and exhaust systems which provide satisfactory attenuation of the effects of external winds on test section flow quality were developed.

  7. 7 x 10-Foot Atmospheric Wind Tunnel (AWT)

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Drawing of 7 x 10-Foot Atmospheric Wind Tunnel (AWT). In 1928, the NACA decided to replace its original Atmospheric Wind Tunnel (AWT #1) with two tunnels--the 5-foot vertical tunnel and a 7 by 10 foot rectangular throat tunnel. Both were open-throat, closed-return-passage tunnels. While the 5-foot vertical tunnel was to be used mainly for spin tests, the 7x10 was an all-purpose tunnel although the main intent was to study stability and control problems. Construction was completed in the summer of 1930; calibration later that same year. The balance was installed and the tunnel went into operation in early 1931. The Warwick Machine Co. of Newport News, Virginia had the contract to fabricate and erection the 7x10-Foot tunnel for a total cost of $18,018.90. The balance was made by Fairbanks, Morse and Co., of Baltimore, Maryland for 2,544.00. The honeycomb was made by the Berkley Machine Works and Foundry Co., Inc. of Norfolk, Virginia for $1,580 and the control panel by Clark Controller Co. of Cleveland, OH for $1,153.

  8. Wind tunnel tests of space shuttle solid rocket booster insulation material in the aerothermal tunnel c

    NASA Technical Reports Server (NTRS)

    Hartman, A. S.; Nutt, K. W.

    1982-01-01

    Wind tunnel tests of the space shuttle Solid Rocket Booster Insulation were conducted in the von Karman Gas Dynamics Facility Tunnel C. For these tests, Tunnel C was run at Mach 4 with a total temperature of 1100-1440 and a total pressure of 100 psia. Cold wall heating rates were changed by varying the test article support wedge angle. Selected results are presented to illustrate the test techniques and typical data obtained.

  9. Tone noise of three supersonic helical tip speed propellers in a wind tunnel at 0.8 Mach number

    NASA Technical Reports Server (NTRS)

    Dittmar, J. H.; Blaha, B. J.; Jeracki, R. J.

    1978-01-01

    Three supersonic helical tip speed propellers were tested in the NASA Lewis 8- by 6-foot wind tunnel. Noise data were obtained while these propellers were operating at a simulated cruise condition. The walls of this tunnel were not acoustically treated and therefore this was not an ideal location for taking noise data, but it was thought that the differences in noise among the three propellers would be meaningful. The straight bladed propeller which did not incorporate sweep was the noisiest with the aerodynamically swept propeller only slightly quieter. However, the acoustically swept propeller was significantly quieter than the straight propeller, thereby indicating the merit of this design technique.

  10. Mass flux similarity for slotted transonic-wind-tunnel walls

    NASA Technical Reports Server (NTRS)

    Everhart, Joel L.; Goradia, Suresh H.

    1991-01-01

    A discussion of the flow field measurements obtained in the vertical plane at several stations along the centerline of slots in two different longitudinally slotted wind tunnel walls is presented. The longitudinal and transverse components of the data are then transformed using the concept of flow similarity to demonstrate the applicability of the technique to the development of the viscous shear flow along and through a slotted wall of an airfoil tunnel. Results are presented showing the performance of the similarity transformations with variations in tunnel station, Mach number, and airfoil induced curvature of the tunnel free stream.

  11. Aerodynamic investigation with focusing schlieren in a cryogenic wind tunnel

    NASA Technical Reports Server (NTRS)

    Gartenberg, Ehud; Weinstein, Leonard M.; Lee, Edwin E., Jr.

    1993-01-01

    A flow visualization study was performed using a focusing schlieren system in the 0.3m Transonic Cryogenic Tunnel at NASA Langley Research Center. The design employed proved to be a useful flow visualization tool for flows as low as M = 0.4. This study marked the first verification of the focusing schlieren technique in a major subsonic/transonic wind tunnel, and the first time that high quality, detailed pictures of high-Reynolds number flows were obtained in a cryogenic wind tunnel. This test was part of a development program to implement instrumentation techniques in cryogenic wind tunnels, with the ultimate aim to use them in the National Transonic Facility (NTF).

  12. Aerodynamic Investigation with focusing schlieren in a cryogenic wind tunnel

    NASA Technical Reports Server (NTRS)

    Gartenberg, Ehud; Weinstein, Leonard M.; Lee Edwin E., JR.

    1994-01-01

    A flow visualization study was performed using a focusing schlieren system in the 0.3m Transonic Cryogenic Tunnel at NASA Langley Research Center. The system proved to be a useful flow visualization tool for flows as low as M = 0.4. This study marked the first verification of the focusing schlieren technique in a major subsonic/transonic wind tunnel and the first time that high-quality, detailed pictures of high-Reynolds-numbers flows were obtained in a cryogenic wind tunnel. This test was part of a development program to implement instrumentation techniques in cryogenic wind tunnels, with the ultimate aim to use them in the National Transonic Facility (NTF).

  13. Supersonic Wind Tunnels (Latest Citations from the Aerospace Database)

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The bibliography contains citations concerning the design, construction, operation, performance, and use of supersonic wind tunnels. References cover the design of flow nozzles, diffusers, test sections, and ejectors for tunnels driven by compressed air, high-pressure gases, or cryogenic liquids. Methods for flow calibration, boundary layer control, local and freestream turbulence reduction, and force measurement are discussed. Instrusive and non-intrusive instrumentation, sources of measurement error, and measurement corrections are also covered. The citations also include the testing of inlets, nozzles, airfoils, and other components of aerospace vehicles that must operate supersonically. Comprehensive coverage of wind tunnel force balancing systems, and blowdown and supersonic wind tunnels are covered in separate bibliographies.(Contains 50-250 citations and includes a subject term index and title list.)

  14. Flight and wind tunnel test results of the mechanical jet noise suppressor nozzle

    NASA Astrophysics Data System (ADS)

    Fitzsimmons, R. D.; McKinnon, R. A.; Johnson, E. S.; Brooks, J. R.

    1980-01-01

    Comprehensive acoustic and propulsion data are presented, based on flight and wind tunnel tests, of a mechanical jet noise suppressor designed to satisfy the requirements of an advanced supersonic transport (AST) under study by the McDonnell Douglas Corporation. The flight program was conducted jointly by MDC, Rolls-Royce Ltd., and the British Aerospace Corporation, using an HS-125 aircraft modified to accept an upgraded RR Viper 601 engine with conical reference and mechanical suppressor nozzles and an acoustically treated ejector. The nacelle, engine and nozzle configurations from the HS-125 were also tested in one of NASA's wind tunnels to obtain thrust performance at forward velocity and acoustic data. The acoustic flight test data, when scaled to an AST engine nozzle size and projected to a typical sideline distance, indicate reduction in effective perceived noise level of 16 EPNdB at the takeoff power setting. It is estimated that the in-flight thrust loss for a typical AST suppressor/ejector nozzle configuration (37.5 inch equivalent diameter) would be 5.4 percent at takeoff power settings and 6.6 percent at cutback power settings.

  15. Aerodynamic and Aeroacoustic Wind Tunnel Testing of the Orion Spacecraft

    NASA Technical Reports Server (NTRS)

    Ross, James C.

    2011-01-01

    The Orion aerodynamic testing team has completed more than 40 tests as part of developing the aerodynamic and loads databases for the vehicle. These databases are key to achieving good mechanical design for the vehicle and to ensure controllable flight during all potential atmospheric phases of a mission, including launch aborts. A wide variety of wind tunnels have been used by the team to document not only the aerodynamics but the aeroacoustic environment that the Orion might experience both during nominal ascents and launch aborts. During potential abort scenarios the effects of the various rocket motor plumes on the vehicle must be accurately understood. The Abort Motor (AM) is a high-thrust, short duration motor that rapidly separates Orion from its launch vehicle. The Attitude Control Motor (ACM), located in the nose of the Orion Launch Abort Vehicle, is used for control during a potential abort. The 8 plumes from the ACM interact in a nonlinear manner with the four AM plumes which required a carefully controlled test to define the interactions and their effect on the control authority provided by the ACM. Techniques for measuring dynamic stability and for simulating rocket plume aerodynamics and acoustics were improved or developed in the course of building the aerodynamic and loads databases for Orion.

  16. Within-Tunnel Variations in Pressure Data for Three Transonic Wind Tunnels

    NASA Technical Reports Server (NTRS)

    DeLoach, Richard

    2014-01-01

    This paper compares the results of pressure measurements made on the same test article with the same test matrix in three transonic wind tunnels. A comparison is presented of the unexplained variance associated with polar replicates acquired in each tunnel. The impact of a significance component of systematic (not random) unexplained variance is reviewed, and the results of analyses of variance are presented to assess the degree of significant systematic error in these representative wind tunnel tests. Total uncertainty estimates are reported for 140 samples of pressure data, quantifying the effects of within-polar random errors and between-polar systematic bias errors.

  17. Using Wind Tunnels to Predict Bird Mortality in Wind Farms: The Case of Griffon Vultures

    PubMed Central

    de Lucas, Manuela; Ferrer, Miguel; Janss, Guyonne F. E.

    2012-01-01

    Background Wind farms have shown a spectacular growth during the last 15 years. Avian mortality through collision with moving rotor blades is well-known as one of the main adverse impacts of wind farms. In Spain, the griffon vulture incurs the highest mortality rates in wind farms. Methodology/Principal Findings As far as we know, this study is the first attempt to predict flight trajectories of birds in order to foresee potentially dangerous areas for wind farm development. We analyse topography and wind flows in relation to flight paths of griffon vultures, using a scaled model of the wind farm area in an aerodynamic wind tunnel, and test the difference between the observed flight paths of griffon vultures and the predominant wind flows. Different wind currents for each wind direction in the aerodynamic model were observed. Simulations of wind flows in a wind tunnel were compared with observed flight paths of griffon vultures. No statistical differences were detected between the observed flight trajectories of griffon vultures and the wind passages observed in our wind tunnel model. A significant correlation was found between dead vultures predicted proportion of vultures crossing those cells according to the aerodynamic model. Conclusions Griffon vulture flight routes matched the predominant wind flows in the area (i.e. they followed the routes where less flight effort was needed). We suggest using these kinds of simulations to predict flight paths over complex terrains can inform the location of wind turbines and thereby reduce soaring bird mortality. PMID:23152764

  18. Wind Turbine Generator System Acoustic Noise Test Report for the Gaia Wind 11-kW Wind Turbine

    SciTech Connect

    Huskey, A.

    2011-11-01

    This report details the acoustic noise test conducted on the Gaia-Wind 11-kW wind turbine at the National Wind Technology Center. The test turbine is a two- bladed, downwind wind turbine with a rated power of 11 kW. The test turbine was tested in accordance with the International Electrotechnical Commission standard, IEC 61400-11 Ed 2.1 2006-11 Wind Turbine Generator Systems -- Part 11 Acoustic Noise Measurement Techniques.

  19. Insights into Airframe Aerodynamics and Rotor-on-Wing Interactions from a 0.25-Scale Tiltrotor Wind Tunnel Model

    NASA Technical Reports Server (NTRS)

    Young, L. A.; Lillie, D.; McCluer, M.; Yamauchi, G. K.; Derby, M. R.

    2001-01-01

    A recent experimental investigation into tiltrotor aerodynamics and acoustics has resulted in the acquisition of a set of data related to tiltrotor airframe aerodynamics and rotor and wing interactional aerodynamics. This work was conducted in the National Full-scale Aerodynamics Complex's (NFAC) 40-by-80 Foot Wind Tunnel, at NASA Ames Research Center, on the Full-Span Tilt Rotor Aeroacoustic Model (TRAM). The full-span TRAM wind tunnel test stand is nominally based on a quarter-scale representation of the V-22 aircraft. The data acquired will enable the refinement of analytical tools for the prediction of tiltrotor aeromechanics and aeroacoustics.

  20. A theory for predicting boundary impedance and resonance frequencies of slotted-wall wind tunnels, including plenum effects

    NASA Technical Reports Server (NTRS)

    Barger, R. L.

    1981-01-01

    Wave-induced resonance associated with the geometry of wind-tunnel test sections can occur. A theory that uses acoustic impedance concepts to predict resonance modes in a two dimensional, slotted wall wind tunnel with a plenum chamber is described. The equation derived is consistent with known results for limiting conditions. The computed resonance modes compare well with appropriate experimental data. When the theory is applied to perforated wall test sections, it predicts the experimentally observed closely spaced modes that occur when the wavelength is not long compared with he plenum depth.

  1. Wind tunnel evaluation of the RAAMP sampler. Final report

    SciTech Connect

    Vanderpool, R.W.; Peters, T.M.

    1994-11-01

    Wind tunnel tests of the Department of Energy RAAMP (Radioactive Atmospheric Aerosol Monitoring Program) monitor have been conducted at wind speeds of 2 km/hr and 24 km/hr. The RAAMP sampler was developed based on three specific performance objectives: (1) meet EPA PM10 performance criteria, (2) representatively sample and retain particles larger than 10 {micro}m for later isotopic analysis, (3) be capable of continuous, unattended operation for time periods up to 2 months. In this first phase of the evaluation, wind tunnel tests were performed to evaluate the sampler as a potential candidate for EPA PM10 reference or equivalency status. As an integral part of the project, the EPA wind tunnel facility was fully characterized at wind speeds of 2 km/hr and 24 km/hr in conjunction with liquid test aerosols of 10 {micro}m aerodynamic diameter. Results showed that the facility and its operating protocols met or exceeded all 40 CFR Part 53 acceptance criteria regarding PM10 size-selective performance evaluation. Analytical procedures for quantitation of collected mass deposits also met 40 CFR Part 53 criteria. Modifications were made to the tunnel`s test section to accommodate the large dimensions of the RAAMP sampler`s instrument case.

  2. CFD wind tunnel test: Field velocity patterns of wind on a building with a refuge floor

    NASA Astrophysics Data System (ADS)

    Cheng, C. K.; Yuen, K. K.; Lam, K. M.; Lo, S. M.

    2005-10-01

    This paper reports a CFD wind tunnel study of wind patterns on a square-plan building with a refuge floor at its mid-height level. In this study, a technique of using calibrated power law equations of velocity and turbulent intensity applied as the boundary conditions in CFD wind tunnel test is being evaluated by the physical wind tunnel data obtained by the Principal Author with wind blowing perpendicularly on the building without a refuge floor. From the evaluated results, an optimised domain of flow required to produce qualitative agreement between the wind tunnel data and simulated results is proposed in this paper. Simulated results with the evaluated technique are validated by the wind tunnel data obtained by the Principal Author. The results contribute to an understanding of the fundamental behaviour of wind flow in a refuge floor when wind is blowing perpendicularly on the building. Moreover, the results reveal that the designed natural ventilation of a refuge floor may not perform desirably when the wind speed on the level is low. Under this situation, the refuge floor may become unsafe if smoke was dispersed in the leeward side of the building at a level immediately below the refuge floor.

  3. Adventures in using a portable wind tunnel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind erosion is a natural process that often occurs wherever loose, dry, erodible soil is exposed to strong erosive winds. The study of wind erosion in the field is quite challenging, with the researcher at the mercy of an unpredictable, large variation in weather factors affecting the outcome. Fie...

  4. Flow Visualization and Laser Velocimetry for Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Hunter, W. W., Jr. (Editor); Foughner, J. T., Jr. (Editor)

    1982-01-01

    The need for flow visualization and laser velocimetry were discussed. The purpose was threefold: (1) provide a state-of-the-art overview; (2) provide a forum for industry, universities, and government agencies to address problems in developing useful and productive flow visualization and laser velocimetry measurement techniques; and (3) provide discussion of recent developments and applications of flow visualization and laser velocimetry measurement techniques and instrumentation systems for wind tunnels including the 0.3-Meter Transonic Cryogenic Tunnel.

  5. Laminar Flow Supersonic Wind Tunnel primary air injector

    NASA Technical Reports Server (NTRS)

    Smith, Brooke Edward

    1993-01-01

    This paper describes the requirements, design, and prototype testing of the flex-section and hinge seals for the Laminar Flow Supersonic Wind Tunnel Primary Injector. The supersonic atmospheric primary injector operates between Mach 1.8 and Mach 2.2 with mass-flow rates of 62 to 128 lbm/s providing the necessary pressure reduction to operate the tunnel in the desired Reynolds number (Re) range.

  6. Structural integrity of wind tunnel wooden fan blades

    NASA Technical Reports Server (NTRS)

    Young, Clarence P., Jr.; Wingate, Robert T.; Rooker, James R.; Mort, Kenneth W.; Zager, Harold E.

    1991-01-01

    Information is presented which was compiled by the NASA Inter-Center Committee on Structural Integrity of Wooden Fan Blades and is intended for use as a guide in design, fabrication, evaluation, and assurance of fan systems using wooden blades. A risk assessment approach for existing NASA wind tunnels with wooden fan blades is provided. Also, state of the art information is provided for wooden fan blade design, drive system considerations, inspection and monitoring methods, and fan blade repair. Proposed research and development activities are discussed, and recommendations are provided which are aimed at future wooden fan blade design activities and safely maintaining existing NASA wind tunnel fan blades. Information is presented that will be of value to wooden fan blade designers, fabricators, inspectors, and wind tunnel operations personnel.

  7. Initial Investigation of Cryogenic Wind Tunnel Model Filler Materials

    NASA Technical Reports Server (NTRS)

    Firth, G. C.

    1985-01-01

    Filler materials are used for surface flaws, instrumentation grooves, and fastener holes in wind tunnel models. More stringent surface quality requirements and the more demanding test environment encountered by cryogenic wind tunnels eliminate filler materials such as polyester resins, plaster, and waxes used on conventional wind tunnel models. To provide a material data base for cryogenic models, various filler materials are investigated. Surface quality requirements and test temperature extremes require matching of coefficients of thermal expansion or interfacing materials. Microstrain versus temperature curves are generated for several candidate filler materials for comparison with cryogenically acceptable materials. Matches have been achieved for aluminum alloys and austenitic steels. Simulated model surfaces are filled with candidate filler materials to determine finishing characteristics, adhesion and stability when subjected to cryogenic cycling. Filler material systems are identified which meet requirements for usage with aluminum model components.

  8. Reducing Wind Tunnel Data Requirements Using Neural Networks

    NASA Technical Reports Server (NTRS)

    Ross, James C.; Jorgenson, Charles C.; Norgaard, Magnus

    1997-01-01

    The use of neural networks to minimize the amount of data required to completely define the aerodynamic performance of a wind tunnel model is examined. The accuracy requirements for commercial wind tunnel test data are very severe and are difficult to reproduce using neural networks. For the current work, multiple input, single output networks were trained using a Levenberg-Marquardt algorithm for each of the aerodynamic coefficients. When applied to the aerodynamics of a 55% scale model of a U.S. Air Force/ NASA generic fighter configuration, this scheme provided accurate models of the lift, drag, and pitching-moment coefficients. Using only 50% of the data acquired during, the wind tunnel test, the trained neural network had a predictive accuracy equal to or better than the accuracy of the experimental measurements.

  9. Accessing Wind Tunnels From NASA's Information Power Grid

    NASA Technical Reports Server (NTRS)

    Becker, Jeff; Biegel, Bryan (Technical Monitor)

    2002-01-01

    The NASA Ames wind tunnel customers are one of the first users of the Information Power Grid (IPG) storage system at the NASA Advanced Supercomputing Division. We wanted to be able to store their data on the IPG so that it could be accessed remotely in a secure but timely fashion. In addition, incorporation into the IPG allows future use of grid computational resources, e.g., for post-processing of data, or to do side-by-side CFD validation. In this paper, we describe the integration of grid data access mechanisms with the existing DARWIN web-based system that is used to access wind tunnel test data. We also show that the combined system has reasonable performance: wind tunnel data may be retrieved at 50Mbits/s over a 100 base T network connected to the IPG storage server.

  10. Wind Tunnel Studies in Aerodynamic Phenomena at High Speed

    NASA Technical Reports Server (NTRS)

    Caldwell, F W; Fales, E N

    1921-01-01

    A great amount of research and experimental work has been done and fair success obtained in an effort to place airplane and propeller design upon an empirical basis. However, one can not fail to be impressed by the apparent lack of data available toward establishing flow phenomena upon a rational basis, such that they may be interpreted in terms of the laws of physics. With this end in view it was the object of the authors to design a wind tunnel differing from the usual type especially in regard to large power and speed of flow. This report describes the wind tunnel at Mccook Field and gives the results of experiments conducted in testing the efficiency of the wind tunnel.

  11. Strain-gage applications in wind tunnel balances

    NASA Astrophysics Data System (ADS)

    Mole, P. J.

    1990-10-01

    Six-component balances used in wind tunnels for precision measurements of air loads on scale models of aircraft and missiles are reviewed. A beam moment-type balance, two-shell balance consisting of an outer shell and inner rod, and air-flow balances used in STOL aircraft configurations are described. The design process, fabrication, gaging, single-gage procedure, and calibration of balances are outlined, and emphasis is placed on computer stress programs and data-reduction computer programs. It is pointed out that these wind-tunnel balances are used in applications for full-scale flight vehicles. Attention is given to a standard two-shell booster balance and an adaptation of a wind-tunnel balance employed to measure the simulated distributed launch loads of a payload in the Space Shuttle.

  12. Cryogenic wind tunnels for high Reynolds number testing

    NASA Technical Reports Server (NTRS)

    Lawing, P. L.; Kilgore, R. A.; Mcguire, P. D.

    1986-01-01

    A compilation of lectures presented at various Universities over a span of several years is discussed. A central theme of these lectures has been to present the research facility in terms of the service it provides to, and its potential effect on, the entire community, rather than just the research community. This theme is preserved in this paper which deals with the cryogenic transonic wind tunnels at Langley Research Center. Transonic aerodynamics is a focus both because of its crucial role in determining the success of aeronautical systems and because cryogenic wind tunnels are especially applicable to the transonics problem. The paper also provides historical perspective and technical background for cryogenic tunnels, culminating in a brief review of cryogenic wind tunnel projects around the world. An appendix is included to provide up to date information on testing techniques that have been developed for the cryogenic tunnels at Langley Research Center. In order to be as inclusive and as current as possible, the appendix is less formal than the main body of the paper. It is anticipated that this paper will be of particular value to the technical layman who is inquisitive as to the value of, and need for, cryogneic tunnels.

  13. SMART Rotor Development and Wind-Tunnel Test

    NASA Technical Reports Server (NTRS)

    Lau, Benton H.; Straub, Friedrich; Anand, V. R.; Birchette, Terry

    2009-01-01

    Boeing and a team from Air Force, NASA, Army, Massachusetts Institute of Technology, University of California at Los Angeles, and University of Maryland have successfully completed a wind-tunnel test of the smart material actuated rotor technology (SMART) rotor in the 40- by 80-foot wind-tunnel of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center, figure 1. The SMART rotor is a full-scale, five-bladed bearingless MD 900 helicopter rotor modified with a piezoelectric-actuated trailing-edge flap on each blade. The development effort included design, fabrication, and component testing of the rotor blades, the trailing-edge flaps, the piezoelectric actuators, the switching power amplifiers, the actuator control system, and the data/power system. Development of the smart rotor culminated in a whirl-tower hover test which demonstrated the functionality, robustness, and required authority of the active flap system. The eleven-week wind tunnel test program evaluated the forward flight characteristics of the active-flap rotor, gathered data to validate state-of-the-art codes for rotor noise analysis, and quantified the effects of open- and closed-loop active-flap control on rotor loads, noise, and performance. The test demonstrated on-blade smart material control of flaps on a full-scale rotor for the first time in a wind tunnel. The effectiveness and the reliability of the flap actuation system were successfully demonstrated in more than 60 hours of wind-tunnel testing. The data acquired and lessons learned will be instrumental in maturing this technology and transitioning it into production. The development effort, test hardware, wind-tunnel test program, and test results will be presented in the full paper.

  14. A Numerical Comparison of Symmetric and Asymmetric Supersonic Wind Tunnels

    NASA Astrophysics Data System (ADS)

    Clark, Kylen D.

    Supersonic wind tunnels are a vital aspect to the aerospace industry. Both the design and testing processes of different aerospace components often include and depend upon utilization of supersonic test facilities. Engine inlets, wing shapes, and body aerodynamics, to name a few, are aspects of aircraft that are frequently subjected to supersonic conditions in use, and thus often require supersonic wind tunnel testing. There is a need for reliable and repeatable supersonic test facilities in order to help create these vital components. The option of building and using asymmetric supersonic converging-diverging nozzles may be appealing due in part to lower construction costs. There is a need, however, to investigate the differences, if any, in the flow characteristics and performance of asymmetric type supersonic wind tunnels in comparison to symmetric due to the fact that asymmetric configurations of CD nozzle are not as common. A computational fluid dynamics (CFD) study has been conducted on an existing University of Michigan (UM) asymmetric supersonic wind tunnel geometry in order to study the effects of asymmetry on supersonic wind tunnel performance. Simulations were made on both the existing asymmetrical tunnel geometry and two axisymmetric reflections (of differing aspect ratio) of that original tunnel geometry. The Reynolds Averaged Navier Stokes equations are solved via NASAs OVERFLOW code to model flow through these configurations. In this way, information has been gleaned on the effects of asymmetry on supersonic wind tunnel performance. Shock boundary layer interactions are paid particular attention since the test section integrity is greatly dependent upon these interactions. Boundary layer and overall flow characteristics are studied. The RANS study presented in this document shows that the UM asymmetric wind tunnel/nozzle configuration is not as well suited to producing uniform test section flow as that of a symmetric configuration, specifically one

  15. Wind tunnel testing of low-drag airfoils

    NASA Technical Reports Server (NTRS)

    Harvey, W. Donald; Mcghee, R. J.; Harris, C. D.

    1986-01-01

    Results are presented for the measured performance recently obtained on several airfoil concepts designed to achieve low drag by maintaining extensive regions of laminar flow without compromising high-lift performance. The wind tunnel results extend from subsonic to transonic speeds and include boundary-layer control through shaping and suction. The research was conducted in the NASA Langley 8-Ft Transonic Pressure Tunnel (TPT) and Low Turbulence Pressure Tunnel (LTPT) which have been developed for testing such low-drag airfoils. Emphasis is placed on identifying some of the major factors influencing the anticipated performance of low-drag airfoils.

  16. exVis and Wind Tunnel Experiment Data

    NASA Technical Reports Server (NTRS)

    Uselton, Samuel P.; Yamasaki-Gerald, Michael (Technical Monitor)

    1998-01-01

    exVis is a software tool created to support interactive display and analysis of data collected during wind tunnel experiments. It is a result of a continuing project to explore the use of information technology in improving the effectiveness of aeronautical design professionals. The data analysis goals are accomplished by allowing aerodynamicists to display and query data collected by new data acquisition systems and to create traditional wind tunnel plots from this data by interactively interrogating these images. Additional information is contained in the original extended abstract.

  17. Development of an intelligent hypertext system for wind tunnel testing

    NASA Technical Reports Server (NTRS)

    Lo, Ching F.; Shi, George Z.; Steinle, Frank W.; Wu, Y. C. L. Susan; Hoyt, W. Andes

    1991-01-01

    This paper summarizes the results of a system utilizing artificial intelligence technology to improve the productivity of project engineers who conduct wind tunnel tests. The objective was to create an intelligent hypertext system which integrates a hypertext manual and expert system that stores experts' knowledge and experience. The preliminary (Phase I) effort implemented a prototype IHS module encompassing a portion of the manuals and knowledge used for wind tunnel testing. The effort successfully demonstrated the feasibility of the intelligent hypertext system concept. A module for the internal strain gage balance, implemented on both IBM-PC and Macintosh computers, is presented. A description of the Phase II effort is included.

  18. Wind-tunnel testing of VTOL and STOL aircraft

    NASA Technical Reports Server (NTRS)

    Heyson, H. H.

    1978-01-01

    The basic concepts of wind-tunnel boundary interference are discussed and the development of the theory for VTOL-STOL aircraft is described. Features affecting the wall interference, such as wake roll-up, configuration differences, recirculation limits, and interference nonuniformity, are discussed. The effects of the level of correction on allowable model size are shown to be amenable to generalized presentation. Finally, experimental confirmation of wind-tunnel interference theory is presented for jet-flap, rotor, and fan-in-wing models.

  19. Integration of computational methods into automotive wind tunnel testing

    SciTech Connect

    Katz, J.

    1989-01-01

    This paper discusses the aerodynamics of a generic, enclosed-wheel racing-car shape without wheels investigated numerically and compared with one-quarter scale wind-tunnel data. Because both methods lack perfection in simulating actual road conditions, a complementary application of these methods was studied. The computations served for correcting the high-blockage wind-tunnel results and provided detailed pressure data which improved the physical understanding of the flow field. The experimental data was used here mainly to provide information on the location of flow-separation lines and on the aerodynamic loads; these in turn were used to validate and to calibrate the computations.

  20. Magnetic Leviation System Design and Implementation for Wind Tunnel Application

    NASA Technical Reports Server (NTRS)

    Lin, Chin E.; Sheu, Yih-Ran; Jou, Hui-Long

    1996-01-01

    This paper presents recent work in magnetic suspension wind tunnel development in National Cheng Kung University. In this phase of research, a control-based study is emphasized to implement a robust control system into the experimental system under study. A ten-coil 10 cm x 10 cm magnetic suspension wind tunnel is built using a set of quadrant detectors for six degree of freedom control. To achieve the attitude control of suspended model with different attitudes, a spacial electromagnetic field simulation using OPERA 3D is studied. A successful test for six degree of freedom control is demonstrated in this paper.

  1. Wind Tunnel Wall Interference Assessment and Correction, 1983

    NASA Technical Reports Server (NTRS)

    Newman, P. A. (Editor); Barnwell, R. W. (Editor)

    1984-01-01

    Technical information focused upon emerging wall interference assessment/correction (WIAC) techniques applicable to transonic wind tunnels with conventional and passively or partially adapted walls is given. The possibility of improving the assessment and correction of data taken in conventional transonic wind tunnels by utilizing simultaneously obtained flow field data (generally taken near the walls) appears to offer a larger, nearer-term payoff than the fully adaptive wall concept. Development of WIAC procedures continues, and aspects related to validating the concept need to be addressed. Thus, the scope of wall interference topics discussed was somewhat limited.

  2. Dataset from chemical gas sensor array in turbulent wind tunnel.

    PubMed

    Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Huerta, Ramón

    2015-06-01

    The dataset includes the acquired time series of a chemical detection platform exposed to different gas conditions in a turbulent wind tunnel. The chemo-sensory elements were sampling directly the environment. In contrast to traditional approaches that include measurement chambers, open sampling systems are sensitive to dispersion mechanisms of gaseous chemical analytes, namely diffusion, turbulence, and advection, making the identification and monitoring of chemical substances more challenging. The sensing platform included 72 metal-oxide gas sensors that were positioned at 6 different locations of the wind tunnel. At each location, 10 distinct chemical gases were released in the wind tunnel, the sensors were evaluated at 5 different operating temperatures, and 3 different wind speeds were generated in the wind tunnel to induce different levels of turbulence. Moreover, each configuration was repeated 20 times, yielding a dataset of 18,000 measurements. The dataset was collected over a period of 16 months. The data is related to "On the performance of gas sensor arrays in open sampling systems using Inhibitory Support Vector Machines", by Vergara et al.[1]. The dataset can be accessed publicly at the UCI repository upon citation of [1]: http://archive.ics.uci.edu/ml/datasets/Gas+sensor+arrays+in+open+sampling+settings. PMID:26217739

  3. Dataset from chemical gas sensor array in turbulent wind tunnel

    PubMed Central

    Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Huerta, Ramón

    2015-01-01

    The dataset includes the acquired time series of a chemical detection platform exposed to different gas conditions in a turbulent wind tunnel. The chemo-sensory elements were sampling directly the environment. In contrast to traditional approaches that include measurement chambers, open sampling systems are sensitive to dispersion mechanisms of gaseous chemical analytes, namely diffusion, turbulence, and advection, making the identification and monitoring of chemical substances more challenging. The sensing platform included 72 metal-oxide gas sensors that were positioned at 6 different locations of the wind tunnel. At each location, 10 distinct chemical gases were released in the wind tunnel, the sensors were evaluated at 5 different operating temperatures, and 3 different wind speeds were generated in the wind tunnel to induce different levels of turbulence. Moreover, each configuration was repeated 20 times, yielding a dataset of 18,000 measurements. The dataset was collected over a period of 16 months. The data is related to “On the performance of gas sensor arrays in open sampling systems using Inhibitory Support Vector Machines”, by Vergara et al.[1]. The dataset can be accessed publicly at the UCI repository upon citation of [1]: http://archive.ics.uci.edu/ml/datasets/Gas+sensor+arrays+in+open+sampling+settings PMID:26217739

  4. 11. INTERIOR VIEW OF 8FOOT HIGH SPEED WIND TUNNEL. SAME ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. INTERIOR VIEW OF 8-FOOT HIGH SPEED WIND TUNNEL. SAME CAMERA POSITION AS VA-118-B-10 LOOKING IN THE OPPOSITE DIRECTION. - NASA Langley Research Center, 8-Foot High Speed Wind Tunnel, 641 Thornell Avenue, Hampton, Hampton, VA

  5. Development of a quiet supersonic wind tunnel with a cryogenic adaptive nozzle

    NASA Technical Reports Server (NTRS)

    Wolf, Stephen W. D.

    1992-01-01

    Aspects of the design and construction of the Laminar Flow Supersonic Wind Tunnel at the NASA-Ames Fluid Mechanics Laboratory are discussed. The wind tunnel is to be used as part of the NASA High Speed Research Program (HSRP).

  6. Measurement of Model Noise in a Hard-Wall Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Soderman, Paul T.

    2006-01-01

    Identification, analysis, and control of fluid-mechanically-generated sound from models of aircraft and automobiles in special low-noise, semi-anechoic wind tunnels are an important research endeavor. Such studies can also be done in aerodynamic wind tunnels that have hard walls if phased microphone arrays are used to focus on the noise-source regions and reject unwanted reflections or background noise. Although it may be difficult to simulate the total flyover or drive-by noise in a closed wind tunnel, individual noise sources can be isolated and analyzed. An acoustic and aerodynamic study was made of a 7-percent-scale aircraft model in a NASA Ames 7-by-10-ft (about 2-by-3-m) wind tunnel for the purpose of identifying and attenuating airframe noise sources. Simulated landing, takeoff, and approach configurations were evaluated at Mach 0.26. Using a phased microphone array mounted in the ceiling over the inverted model, various noise sources in the high-lift system, landing gear, fins, and miscellaneous other components were located and compared for sound level and frequency at one flyover location. Numerous noise-alleviation devices and modifications of the model were evaluated. Simultaneously with acoustic measurements, aerodynamic forces were recorded to document aircraft conditions and any performance changes caused by geometric modifications. Most modern microphone-array systems function in the frequency domain in the sense that spectra of the microphone outputs are computed, then operations are performed on the matrices of microphone-signal cross-spectra. The entire acoustic field at one station in such a system is acquired quickly and interrogated during postprocessing. Beam-forming algorithms are employed to scan a plane near the model surface and locate noise sources while rejecting most background noise and spurious reflections. In the case of the system used in this study, previous studies in the wind tunnel have identified noise sources up to 19 d

  7. Design and calibration of the mixing layer and wind tunnel

    NASA Technical Reports Server (NTRS)

    Bell, James H.; Mehta, Rabindra D.

    1989-01-01

    A detailed account of the design, assembly and calibration of a wind tunnel specifically designed for free-shear layer research is contained. The construction of this new facility was motivated by a strong interest in the study of plane mixing layers with varying initial and operating conditions. The Mixing Layer Wind tunnel is located in the Fluid Mechanics Laboratory at NASA Ames Research Center. The tunnel consists of two separate legs which are driven independently by centrifugal blowers connected to variable speed motors. The blower/motor combinations are sized such that one is smaller than the other, giving maximum flow speeds of about 20 and 40 m/s, respectively. The blower speeds can either be set manually or via the Microvax II computer. The two streams are allowed to merge in the test section at the sharp trailing edge of a slowly tapering splitter plate. The test section is 36 cm in the cross-stream direction, 91 cm in the spanwise direction and 366 cm in length. One test section side-wall is slotted for probe access and adjustable so that the streamwise pressure gradient may be controlled. The wind tunnel is also equipped with a computer controlled, three-dimensional traversing system which is used to investigate the flow fields with pressure and hot-wire instrumentation. The wind tunnel calibration results show that the mean flow in the test section is uniform to within plus or minus 0.25 pct and the flow angularity is less than 0.25 deg. The total streamwise free-stream turbulence intensity level is approximately 0.15 pct. Currently the wind tunnel is being used in experiments designed to study the three-dimensional structure of plane mixing layers and wakes.

  8. Microspheres for laser velocimetry in high temperature wind tunnel

    NASA Technical Reports Server (NTRS)

    Ghorieshi, Anthony

    1993-01-01

    The introduction of non-intrusive measurement techniques in wind tunnel experimentation has been a turning point in error free data acquisition. Laser velocimetry has been progressively implemented and utilized in various wind tunnels; e.g. subsonic, transonic, and supersonic. The success of the laser velocimeter technique is based on an accurate measurement of scattered light by seeding particles introduced into the flow stream in the wind tunnel. Therefore, application of appropriate seeding particles will affect, to a large extent the acquired data. The seeding material used depends on the type of experiment being run. Among the seeding material for subsonic tunnel are kerosene, Kaolin, and polystyrene. Polystyrene is known to be the best because of being solid particles, having high index of refraction, capable of being made both spherical and monodisperse. However for high temperature wind tunnel testing seeding material must have an additional characteristic that is high melting point. Typically metal oxide powders such as Al2O3 with melting point 3660 F are used. The metal oxides are, however polydispersed, have a high density, and a tendency to form large agglomerate that does not closely follow the flow velocity. The addition of flame phase silica to metal oxide helps to break up the agglomerates, yet still results in a narrow band of polydispersed seeding. The less desirable utility of metal oxide in high temperature wind tunnels necessitates the search for a better alternative particle seeding which this paper addresses. The Laser Velocimetry (LV) characteristic of polystyrene makes it a prime candidate as a base material in achieving the high temperature particle seeding inexpensively. While polystyrene monodisperse seeding particle reported has been successful in a subsonic wind tunnel, it lacks the high melting point and thus is not practically usable in a high temperature wind tunnel. It is well known that rise in melting point of polystyrene can be

  9. An experimental study of several wind tunnel wall configurations using two V/STOL model configurations. [low speed wind tunnels

    NASA Technical Reports Server (NTRS)

    Binion, T. W., Jr.

    1975-01-01

    Experiments were conducted in the low speed wind tunnel using two V/STOL models, a jet-flap and a jet-in-fuselage configuration, to search for a wind tunnel wall configuration to minimize wall interference on V/STOL models. Data were also obtained on the jet-flap model with a uniform slotted wall configuration to provide comparisons between theoretical and experimental wall interference. A test section configuration was found which provided some data in reasonable agreement with interference-free results over a wide range of momentum coefficients.

  10. Study of ice accretion on icing wind tunnel components

    NASA Technical Reports Server (NTRS)

    Newton, J. E.; Olsen, W.

    1986-01-01

    In a closed loop icing wind tunnel the icing cloud is simulated by introducing tiny water droplets through an array of nozzles upstream of the test section. This cloud will form ice on all tunnel components (e.g., turning vanes, inlet guide vanes, fan blades, and the heat exchanger) as the cloud flows around the tunnel. These components must have the capacity to handle their icing loads without causing significant tunnel performance degradation during the course of an evening's run. To aid in the design of these components for the proposed Altitude Wind Tunnel (AWT) at NASA Lewis Research Center the existing Icing Research Tunnel (IRT) is used to measure icing characteristics of the IRT's components. The results from the IRT are scaled to the AWT to account for the AWT's larger components and higher velocities. The results show that from 90 to 45 percent of the total spray cloud froze out on the heat exchanger. Furthermore, the first set of turning vanes downstream of the test section, the FOD screen and the fan blades show significant ice formation. The scaling shows that the same results would occur in the AWT.

  11. The 4 x 7 M modeling program. [NASA Langley wind tunnel

    NASA Technical Reports Server (NTRS)

    Applin, Zachery T.

    1984-01-01

    The use of small scale modeling in defining flow improvements for the Langley 4 x 7 meter wind tunnel is presented. Topics covered in viewgraph format include: description of the 4 x 7 meter wind tunnel, description of the 1/24 scale model, wind tunnel circuit flow characteristics, open test section turbulence characteristics, and conclusions.

  12. 40 CFR 53.62 - Test procedure: Full wind tunnel test.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Test procedure: Full wind tunnel test... Performance Characteristics of Class II Equivalent Methods for PM2.5 § 53.62 Test procedure: Full wind tunnel test. (a) Overview. The full wind tunnel test evaluates the effectiveness of the candidate sampler at...

  13. 40 CFR 53.62 - Test procedure: Full wind tunnel test.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Test procedure: Full wind tunnel test... Performance Characteristics of Class II Equivalent Methods for PM 2.5 § 53.62 Test procedure: Full wind tunnel test. (a) Overview. The full wind tunnel test evaluates the effectiveness of the candidate sampler at...

  14. Boundary Layer Transition on Slender Cones in Conventional and Low Disturbance Mach 6 Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Horvath, Thomas J.; Berry, Scott A.; Hollis, Brian R.; Chang, Chau-Lyan; Singer, Bart A.

    2002-01-01

    An experimental investigation was conducted on a 5-degree half-angle cone and a 5-degree half-angle flared cone in a conventional Mach 6 wind tunnel to examine the effects of facility noise on boundary layer transition. The influence of tunnel noise was inferred by comparing transition onset locations determined from the present test to that previously obtained in a Mach 6 low disturbance quiet tunnel. Together, the two sets of experiments are believed to represent the first direct comparison of transition onset between a conventional and a low disturbance wind tunnel using a common test model and transition detection technique. In the present conventional hypersonic tunnel experiment, separate measurements of heat transfer and adiabatic wall temperatures were obtained on the conical models at small angles of attack over a range of Reynolds numbers, which resulted in laminar, transitional, and turbulent flow. Smooth model turbulent heating distributions are compared to that obtained with transition forced via discrete surface roughness. The model nosetip radius was varied to examine the effects of bluntness on transition onset. Despite wall to total temperature differences between the transient heating measurements and the adiabatic wall temperature measurement, the two methods for determining sharp cone transition onset generally yielded equivalent locations. In the 'noisy' mode of the hypersonic low disturbance tunnel, transition onset occurred earlier than that measured in the conventional hypersonic tunnel, suggesting higher levels of freestream acoustic radiation relative to the conventional tunnel. At comparable freestream conditions, the transition onset Reynolds number under low disturbance conditions was a factor of 1.3 greater than that measured on flared cone in the LaRC conventional hypersonic tunnel and a factor of 1.6 greater that the flared cone run in the low disturbance tunnel run 'noisy'. Navier-Stokes mean flow computations and linear stability

  15. Comparison of wind tunnel airfoil performance data with wind turbine blade data

    SciTech Connect

    Butterfield, C.P.; Scott, G.; Musial, W. )

    1992-05-01

    Horizontal axis wind turbine (HAWT) performance is usually predicted by using wind tunnel airfoil performance data in a blade element momentum theory analysis. This analysis assumes that the rotating blade airfoils will perform as they do in the wind tunnel. Results to date have shown that unsteady aerodynamics exist during all operating conditions and dynamic stall can exist for high yaw angle operation. Stall hysteresis occurs for even small way angles and delayed stall is a very persistent reality in all operating conditions. delayed stall is indicated by a leading edge suction peak which remains attached through angles of attack (AOA) up to 30 degrees. Wind tunnel results show this peak separating from the leading edge at 18 deg AOA. The effect of this anomaly is to raise normal force coefficients and tangent force coefficients for high AOA. Increase tangent forces will directly affect HAWT performance in high wind speed operation. This paper describes pressure distribution data resulting from both wind tunnel and HAWT tests. A method of bins is used to average the HAWT data which is compared to the wind tunnel data. The analysis technique and the test set-up for each test are described.

  16. Development of an Intelligent Videogrammetric Wind Tunnel Measurement System

    NASA Technical Reports Server (NTRS)

    Graves, Sharon S.; Burner, Alpheus W.

    2004-01-01

    A videogrammetric technique developed at NASA Langley Research Center has been used at five NASA facilities at the Langley and Ames Research Centers for deformation measurements on a number of sting mounted and semispan models. These include high-speed research and transport models tested over a wide range of aerodynamic conditions including subsonic, transonic, and supersonic regimes. The technique, based on digital photogrammetry, has been used to measure model attitude, deformation, and sting bending. In addition, the technique has been used to study model injection rate effects and to calibrate and validate methods for predicting static aeroelastic deformations of wind tunnel models. An effort is currently underway to develop an intelligent videogrammetric measurement system that will be both useful and usable in large production wind tunnels while providing accurate data in a robust and timely manner. Designed to encode a higher degree of knowledge through computer vision, the system features advanced pattern recognition techniques to improve automated location and identification of targets placed on the wind tunnel model to be used for aerodynamic measurements such as attitude and deformation. This paper will describe the development and strategy of the new intelligent system that was used in a recent test at a large transonic wind tunnel.

  17. Investigations and Experiments in the Guidonia Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Ferri, Antonio

    1939-01-01

    This paper is a presentation of the experiments and equipment used in investigations at the Guidonia wind tunnel. The equipment consisted of: a number of subsonic and supersonic cones, an aerodynamic balance, and optical instruments operating on the Schlieren and interferometer principle.

  18. A Modified Bagnold-Type Wind Tunnel for Laboratory Use

    ERIC Educational Resources Information Center

    Logan, Alan

    1975-01-01

    Using the basic Bagnold design, a relatively inexpensive suction-type wind tunnel can be constructed for laboratory demonstration of sand-grain movement, ripple development, and other eolian processes. Its simple design provides no workshop problems and it can be made for a total cost in materials of approximately $225. (Author/CP)

  19. A voice-actuated wind tunnel model leak checking system

    NASA Technical Reports Server (NTRS)

    Larson, W. E.

    1985-01-01

    A voice-actuated wind tunnel model leak checking system was developed. The system uses a voice recognition and response unit to interact with the technician along with a graphics terminal to provide the technician with visual feedback while checking a model for leaks.

  20. Support interference of wind tunnel models: A selective annotated bibliography

    NASA Technical Reports Server (NTRS)

    Tuttle, M. H.; Gloss, B. B.

    1981-01-01

    This bibliography, with abstracts, consists of 143 citations arranged in chronological order by dates of publication. Selection of the citations was made for their relevance to the problems involved in understanding or avoiding support interference in wind tunnel testing throughout the Mach number range. An author index is included.

  1. Calibrated cylindrical Mach probe in a plasma wind tunnel

    SciTech Connect

    Zhang, X.; Dandurand, D.; Gray, T.; Brown, M. R.; Lukin, V. S.

    2011-03-15

    A simple cylindrical Mach probe is described along with an independent calibration procedure in a magnetized plasma wind tunnel. A particle orbit calculation corroborates our model. The probe operates in the weakly magnetized regime in which probe dimension and ion orbit are of the same scale. Analytical and simulation models are favorably compared with experimental calibration.

  2. Full Scale Wind Tunnel and Seaplane Tow Channel

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Construction progress, aerials of East Area. L5169: Langley's seaplane towing facility (right) and the Full Scale Tunnel (left) were photographed in November of 1930. Photograph published in Winds of Change, 75th Anniversary NASA publication (page 39), by James Schultz.

  3. Ares I Aerodynamic Testing at the Boeing Polysonic Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Pinier, Jeremy T.; Niskey, Charles J.; Hanke, Jeremy L.; Tomek, William G.

    2011-01-01

    Throughout three full design analysis cycles, the Ares I project within the Constellation program has consistently relied on the Boeing Polysonic Wind Tunnel (PSWT) for aerodynamic testing of the subsonic, transonic and supersonic portions of the atmospheric flight envelope (Mach=0.5 to 4.5). Each design cycle required the development of aerodynamic databases for the 6 degree-of-freedom (DOF) forces and moments, as well as distributed line-loads databases covering the full range of Mach number, total angle-of-attack, and aerodynamic roll angle. The high fidelity data collected in this facility has been consistent with the data collected in NASA Langley s Unitary Plan Wind Tunnel (UPWT) at the overlapping condition ofMach=1.6. Much insight into the aerodynamic behavior of the launch vehicle during all phases of flight was gained through wind tunnel testing. Important knowledge pertaining to slender launch vehicle aerodynamics in particular was accumulated. In conducting these wind tunnel tests and developing experimental aerodynamic databases, some challenges were encountered and are reported as lessons learned in this paper for the benefit of future crew launch vehicle aerodynamic developments.

  4. The requirements for a new full scale subsonic wind tunnel

    NASA Technical Reports Server (NTRS)

    Kelly, M. W.; Mckinney, M. O.; Luidens, R. W.

    1972-01-01

    Justification and requirements are presented for a large subsonic wind tunnel capable of testing full scale aircraft, rotor systems, and advanced V/STOL propulsion systems. The design considerations and constraints for such a facility are reviewed, and the trades between facility test capability and costs are discussed.

  5. Support interference of wind tunnel models: A selective annotated bibliography

    NASA Technical Reports Server (NTRS)

    Tuttle, M. H.; Lawing, P. L.

    1984-01-01

    This bibliography, with abstracts, consists of 143 citations arranged in chronological order by dates of publication. Selection of the citations was made for their relevance to the problems involved in understanding or avoiding support interference in wind tunnel testing throughout the Mach number range. An author index is included.

  6. Static and wind tunnel model tests for the development of externally blown flap noise reduction techniques

    NASA Technical Reports Server (NTRS)

    Pennock, A. P.; Swift, G.; Marbert, J. A.

    1975-01-01

    Externally blown flap models were tested for noise and performance at one-fifth scale in a static facility and at one-tenth scale in a large acoustically-treated wind tunnel. The static tests covered two flap designs, conical and ejector nozzles, third-flap noise-reduction treatments, internal blowing, and flap/nozzle geometry variations. The wind tunnel variables were triple-slotted or single-slotted flaps, sweep angle, and solid or perforated third flap. The static test program showed the following noise reductions at takeoff: 1.5 PNdB due to treating the third flap; 0.5 PNdB due to blowing from the third flap; 6 PNdB at flyover and 4.5 PNdB in the critical sideline plane (30 deg elevation) due to installation of the ejector nozzle. The wind tunnel program showed a reduction of 2 PNdB in the sideline plane due to a forward speed of 43.8 m/s (85 kn). The best combination of noise reduction concepts reduced the sideline noise of the reference aircraft at constant field length by 4 PNdB.

  7. The cryogenic wind tunnel concept for high Reynolds number testing

    NASA Technical Reports Server (NTRS)

    Kilgore, R. A.; Goodyer, M. J.; Adcock, J. B.; Davenport, E. E.

    1974-01-01

    Theoretical considerations indicate that cooling the wind-tunnel test gas to cryogenic temperatures will provide a large increase in Reynolds number with no increase in dynamic pressure while reducing the tunnel drive-power requirements. Studies were made to determine the expected variations of Reynolds number and other parameters over wide ranges of Mach number, pressure, and temperature, with due regard to avoiding liquefaction. Practical operational procedures were developed in a low-speed cryogenic tunnel. Aerodynamic experiments in the facility demonstrated the theoretically predicted variations in Reynolds number and drive power. The continuous-flow-fan-driven tunnel is shown to be particularly well suited to take full advantage of operating at cryogenic temperatures.

  8. SOFIA 2 model telescope wind tunnel test report

    NASA Technical Reports Server (NTRS)

    Keas, Paul

    1995-01-01

    This document outlines the tests performed to make aerodynamic force and torque measurements on the SOFIA wind tunnel model telescope. These tests were performed during the SOFIA 2 wind tunnel test in the 14 ft wind tunnel during the months of June through August 1994. The test was designed to measure the dynamic cross elevation moment acting on the SOFIA model telescope due to aerodynamic loading. The measurements were taken with the telescope mounted in an open cavity in the tail section of the SOFIA model 747. The purpose of the test was to obtain an estimate of the full scale aerodynamic disturbance spectrum, by scaling up the wind tunnel results (taking into account differences in sail area, air density, cavity dimension, etc.). An estimate of the full scale cross elevation moment spectrum was needed to help determine the impact this disturbance would have on the telescope positioning system requirements. A model of the telescope structure, made of a light weight composite material, was mounted in the open cavity of the SOFIA wind tunnel model. This model was mounted via a force balance to the cavity bulkhead. Despite efforts to use a 'stiff' balance, and a lightweight model, the balance/telescope system had a very low resonant frequency (37 Hz) compared to the desired measurement bandwidth (1000 Hz). Due to this mechanical resonance of the balance/telescope system, the balance alone could not provide an accurate measure of applied aerodynamic force at the high frequencies desired. A method of measurement was developed that incorporated accelerometers in addition to the balance signal, to calculate the aerodynamic force.

  9. Assessment of Scaled Rotors for Wind Tunnel Experiments.

    SciTech Connect

    Maniaci, David Charles; Kelley, Christopher Lee; Chiu, Phillip

    2015-07-01

    Rotor design and analysis work has been performed to support the conceptualization of a wind tunnel test focused on studying wake dynamics. This wind tunnel test would serve as part of a larger model validation campaign that is part of the Department of Energy Wind and Water Power Program’s Atmosphere to electrons (A2e) initiative. The first phase of this effort was directed towards designing a functionally scaled rotor based on the same design process and target full-scale turbine used for new rotors for the DOE/SNL SWiFT site. The second phase focused on assessing the capabilities of an already available rotor, the G1, designed and built by researchers at the Technical University of München.

  10. Supersonic wind tunnel nozzles: A selected, annotated bibliography to aid in the development of quiet wind tunnel technology

    NASA Technical Reports Server (NTRS)

    Wolf, Stephen W. D.

    1990-01-01

    This bibliography, with abstracts, consists of 298 citations arranged in chronological order. The citations were selected to be helpful to persons engaged in the design and development of quiet (low disturbance) nozzles for modern supersonic wind tunnels. Author, subject, and corporate source indexes are included to assist with the location of specific information.

  11. Wind, waves, and acoustic background levels at Station ALOHA

    NASA Astrophysics Data System (ADS)

    Duennebier, Fred K.; Lukas, Roger; Nosal, Eva-Marie; Aucan, JéRome; Weller, Robert A.

    2012-03-01

    Frequency spectra from deep-ocean near-bottom acoustic measurements obtained contemporaneously with wind, wave, and seismic data are described and used to determine the correlations among these data and to discuss possible causal relationships. Microseism energy appears to originate in four distinct regions relative to the hydrophone: wind waves above the sensors contribute microseism energy observed on the ocean floor; a fraction of this local wave energy propagates as seismic waves laterally, and provides a spatially integrated contribution to microseisms observed both in the ocean and on land; waves in storms generate microseism energy in deep water that travels as seismic waves to the sensor; and waves reflected from shorelines provide opposing waves that add to the microseism energy. Correlations of local wind speed with acoustic and seismic spectral time series suggest that the local Longuet-Higgins mechanism is visible in the acoustic spectrum from about 0.4 Hz to 80 Hz. Wind speed and acoustic levels at the hydrophone are poorly correlated below 0.4 Hz, implying that the microseism energy below 0.4 Hz is not typically generated by local winds. Correlation of ocean floor acoustic energy with seismic spectra from Oahu and with wave spectra near Oahu imply that wave reflections from Hawaiian coasts, wave interactions in the deep ocean near Hawaii, and storms far from Hawaii contribute energy to the seismic and acoustic spectra below 0.4 Hz. Wavefield directionality strongly influences the acoustic spectrum at frequencies below about 2 Hz, above which the acoustic levels imply near-isotropic surface wave directionality.

  12. Fire in Variable Density Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1927-01-01

    Fire gutted interior of Variable-Density Tunnel (VDT). On August 1, 1927 a major fire broke out inside the VDT. Clean-up, repair, redesign and reinstallation of equipment took about 8 months. From the Variable Density Tunnel Log Book: 'Aug. 1. Computation of the previous tests were in progress in the office and the tank had been pumped up to 20 atmospheres and run to equalize the temperatures about 11:25 a.m. The 20 atmosphere run on the M-6 polished air foil was started and two readings had been taken when sparks were seen to pass in the return passage. Mr. Turner yelled 'Fire!' and shut off the drive motor and opened the blow off valve. Through the peep holes it could be seen that the fire had a good start. It soon fogged up inside so that it could no longer be seen. We then waited for the pressure to go down. However, due to the burning inside, the pressure probably continued to rise. We noticed that the blow off pipe was becoming very hot and that smoke was coming out around the propeller shaft. Suddenly (sic) there was a loud bursting noise and every one left the building. This was probably the blowing of the gasket around the blow off valve. Later the top peep hole blew out and the blow off pipe blew out from the valve. The pressure then began to go down and we returned. The building was full of smoke. When the pressure had gone down the blow off was closed. The tank was very hot and the roof of the building somewhat scorched. The office was then partially cleaned up but it was decided to leave the tunnel closed until the next day.' 'Aug. 2. The tunnel door was opened in the morning and the compressor run to expel the gasses. About noon it was possible to swing back then honeycomb. It was apparent that the damage was very wide spread. All of the woodwork seemed to be charred and the upper part of the balance ring and the propeller tips and glass windows near the test section were melted. The remainder of the day was spent ventilating the tunnel and taking

  13. Fire in Variable Density Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1927-01-01

    Fire gutted interior of Variable-Density Tunnel (VDT). On August 1, 1927 a major fire broke out inside the VDT. Clean-up, repair, redesign and reinstallation of equipment took about 8 months. From the Variable Density Tunnel Log Book: 'Aug. 1. Computation of the previous tests were in progress in the office and the tank had been pumped up to 20 atmospheres and run to equalize the temperatures about 11:25 a.m. The 20 atmosphere run on the M-6 polished air foil was started and two readings had been taken when sparks were seen to pass in the return passage. Mr. Turner yelled 'Fire!' and shut off the drive motor and opened the blow off valve. Through the peep holes it could be seen that the fire had a good start. It soon fogged up inside so that it could no longer be seen. We then waited for the pressure to go down. However, due to the burning inside, the pressure probably continued to rise. We noticed that the blow off pipe was becoming very hot and that smoke was coming out around the propeller shaft. Suddenly (sic) there was a loud bursting noise and every one left the building. This was probably the blowing of the gasket around the blow off valve. Later the top peep hole blew out and the blow off pipe blew out from the valve. The pressure then began to go down and we returned. The building was full of smoke. When the pressure had gone down the blow off was closed. The tank was very hot and the roof of the building somewhat scorched. The office was then partially cleaned up but it was decided to leave the tunnel closed until the next day.' 'Aug. 2. The tunnel door was opened in the morning and the compressor run to expel the gasses. About noon it was possible to swing back the honeycomb. It was apparent that the damage was very wide spread. All of the woodwork seemed to be charred and the upper part of the balance ring and the propeller tips and glass windows near the test section were melted. The remainder of the day was spent ventilating the tunnel and taking

  14. Study of optical techniques for the Ames unitary wind tunnel, part 7

    NASA Technical Reports Server (NTRS)

    Lee, George

    1993-01-01

    A summary of optical techniques for the Ames Unitary Plan wind tunnels are discussed. Six optical techniques were studied: Schlieren, light sheet and laser vapor screen, angle of attack, model deformation, infrared imagery, and digital image processing. The study includes surveys and reviews of wind tunnel optical techniques, some conceptual designs, and recommendations for use of optical methods in the Ames Unitary Plan wind tunnels. Particular emphasis was placed on searching for systems developed for wind tunnel use and on commercial systems which could be readily adapted for wind tunnels. This final report is to summarize the major results and recommendations.

  15. 40 CFR 53.63 - Test procedure: Wind tunnel inlet aspiration test.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Test procedure: Wind tunnel inlet... Testing Performance Characteristics of Class II Equivalent Methods for PM 2.5 § 53.63 Test procedure: Wind... extracts an ambient aerosol at elevated wind speeds. This wind tunnel test uses a single-sized,...

  16. 40 CFR 53.63 - Test procedure: Wind tunnel inlet aspiration test.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Test procedure: Wind tunnel inlet... Testing Performance Characteristics of Class II Equivalent Methods for PM2.5 § 53.63 Test procedure: Wind... extracts an ambient aerosol at elevated wind speeds. This wind tunnel test uses a single-sized,...

  17. 40 CFR 53.63 - Test procedure: Wind tunnel inlet aspiration test.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Test procedure: Wind tunnel inlet... Testing Performance Characteristics of Class II Equivalent Methods for PM 2.5 § 53.63 Test procedure: Wind... extracts an ambient aerosol at elevated wind speeds. This wind tunnel test uses a single-sized,...

  18. Design, construction and calibration of a portable boundary layer wind tunnel for field use

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind tunnels have been used for several decades to study wind erosion processes. Portable wind tunnels offer the advantage of testing natural surfaces in the field, but they must be carefully designed to insure that a logarithmic boundary layer is formed and that wind erosion processes may develop ...

  19. N-231 High Reynolds Number Channel Facility (An example of a Versatile Wind Tunnel) Tunnel 1 I is a

    NASA Technical Reports Server (NTRS)

    1980-01-01

    N-231 High Reynolds Number Channel Facility (An example of a Versatile Wind Tunnel) Tunnel 1 I is a blowdown Facility that utilizes interchangeable test sections and nozzles. The facility provides experimental support for the fluid mechanics research, including experimental verification of aerodynamic computer codes and boundary-layer and airfoil studies that require high Reynolds number simulation. (Tunnel 1)

  20. Cost effective use of liquid nitrogen in cryogenic wind tunnels

    NASA Technical Reports Server (NTRS)

    Mcintosh, Glen E.; Lombard, David S.; Martindale, David L.; Dunn, Robert P.

    1987-01-01

    A method of reliquefying from 12 to 19% of the nitrogen exhaust gas from a cryogenic wind tunnel has been developed. Technical feasibility and cost effectiveness of the system depends on performance of an innovative positive displacement expander which requires scale model testing to confirm design studies. The existing cryogenic system at the 0.3-m transonic cryogenic tunnel has been surveyed and extensive upgrades proposed. Upgrades are generally cost effective and may be implemented immediately since they are based on established technology.

  1. A survey of the three-dimensional high Reynolds number transonic wind tunnel

    NASA Technical Reports Server (NTRS)

    Takashima, K.; Sawada, H.; Aoki, T.

    1982-01-01

    The facilities for aerodynamic testing of airplane models at transonic speeds and high Reynolds numbers are surveyed. The need for high Reynolds number testing is reviewed, using some experimental results. Some approaches to high Reynolds number testing such as the cryogenic wind tunnel, the induction driven wind tunnel, the Ludwieg tube, the Evans clean tunnel and the hydraulic driven wind tunnel are described. The level of development of high Reynolds number testing facilities in Japan is discussed.

  2. A method for data base management and analysis for wind tunnel data

    NASA Technical Reports Server (NTRS)

    Biser, Aileen O.

    1987-01-01

    To respond to the need for improved data base management and analysis capabilities for wind-tunnel data at the Langley 16-Foot Transonic Tunnel, research was conducted into current methods of managing wind-tunnel data and a method was developed as a solution to this need. This paper describes the development of the data base management and analysis method for wind-tunnel data. The design and implementation of the software system are discussed and examples of its use are shown.

  3. Design and fabrication of forward-swept counterrotation blade configuration for wind tunnel testing

    NASA Technical Reports Server (NTRS)

    Nichols, G. H.

    1994-01-01

    Work performed by GE Aircraft on advanced counterrotation blade configuration concepts for high speed turboprop system is described. Primary emphasis was placed on theoretically and experimentally evaluating the aerodynamic, aeromechanical, and acoustic performance of GE-defined counterrotating blade concepts. Several blade design concepts were considered. Feasibility studies were conducted to evaluate a forward-swept versus an aft-swept blade application and how the given blade design would affect interaction between rotors. Two blade designs were initially selected. Both designs involved in-depth aerodynamic, aeromechanical, mechanical, and acoustic analyses followed by the fabrication of forward-swept, forward rotor blade sets to be wind tunnel tested with an aft-swept, aft rotor blade set. A third blade set was later produced from a NASA design that was based on wind tunnel test results from the first two blade sets. This blade set had a stiffer outer ply material added to the original blade design, in order to reach the design point operating line. Detailed analyses, feasibility studies, and fabrication procedures for all blade sets are presented.

  4. Background noise levels measured in the NASA Lewis 9- by 15-foot low-speed wind tunnel

    NASA Technical Reports Server (NTRS)

    Woodward, Richard P.; Dittmar, James H.; Hall, David G.; Kee-Bowling, Bonnie

    1994-01-01

    The acoustic capability of the NASA Lewis 9 by 15 Foot Low Speed Wind Tunnel has been significantly improved by reducing the background noise levels measured by in-flow microphones. This was accomplished by incorporating streamlined microphone holders having a profile developed by researchers at the NASA Ames Research Center. These new holders were fabricated for fixed mounting on the tunnel wall and for an axially traversing microphone probe which was mounted to the tunnel floor. Measured in-flow noise levels in the tunnel test section were reduced by about 10 dB with the new microphone holders compared with those measured with the older, less refined microphone holders. Wake interference patterns between fixed wall microphones were measured and resulted in preferred placement patterns for these microphones to minimize these effects. Acoustic data from a model turbofan operating in the tunnel test section showed that results for the fixed and translating microphones were equivalent for common azimuthal angles, suggesting that the translating microphone probe, with its significantly greater angular resolution, is preferred for sideline noise measurements. Fixed microphones can provide a local check on the traversing microphone data quality, and record acoustic performance at other azimuthal angles.

  5. A study of the noise radiation from four helicopter rotor blades. [tests in Ames 40 by 20 foot wind tunnel

    NASA Technical Reports Server (NTRS)

    Lee, A.; Mosher, M.

    1978-01-01

    Acoustic measurements were taken of a modern helicopter rotor with four blade tip shapes in the NASA Ames 40-by-80-Foot Wind Tunnel. The four tip shapes are: rectangular, swept, trapezoidal, and swept tapered in platform. Acoustic effects due to tip shape changes were studied based on the dBA level, peak noise pressure, and subjective rating. The swept tapered blade was found to be the quietest above an advancing tip Mach number of about 0.9, and the swept blade was the quietest at low speed. The measured high speed impulsive noise was compared with theoretical predictions based on thickness effects; good agreement was found.

  6. The 2009 ESA/Danish Mars Simulation Wind Tunnel Facility

    NASA Astrophysics Data System (ADS)

    Nornberg, P.; Merrison, J. P.; Gunnlaugsson, H. P.

    2009-04-01

    Simulation of the dynamic environment in immediate proximity to the surface of Mars requires access to simulation facilities which can reproduce the atmospheric properties (pressure, temperature, gas composition, UV-VIS light conditions, wind flow etc.). It also requires access to analogue Martian surface material (soil and dust). Simulations can be carried out in a wind tunnel placed in a tank which can be pumped out, like the 400 mm Ø, 1500 mm long wind tunnel that has operated in the Mars Simulation Laboratory at University of Aarhus, Denmark since 2000 (1). A wide range of applications have taken place, from development, test and calibration of instruments, over tests of solar panels, and aerodynamic studies of granular transport to studies of physical properties of dust materials such as grain electrification, aggregation and magnetic properties (2,3). The Salten Skov I analogue (4) and other Martian regolits and dust analogues have been used in the wind tunnel experiments. With the view to future instrument development, solar panel optimization and future research on Martian surface processes a new ESA supported wind tunnel has been constructed at University of Aarhus, Denmark and is now under building. This wind tunnel will have a cross section of close to 1 x 2 m and be able to reach a wind speed of close to 30 m/s under Martian pressure conditions and with samples cooled down to Martian temperatures. The facility is planned to be finally tested and ready for use in July 2009. ESA, ExoMars use of this facility will have priority. However, research projects in collaboration with external users will also be welcome in the future. Later this year information on access possibilities will be announced at the Mars Simulation Laboratory home page: www.marslab.dk. References: (1) Merrison, J., Bertelsen, P., Frandsen, C., Gunnlaugsson, H.P., Knudsen, J.M., Madsen, M.B., Mossin, L., Nielsen, J., Nørnberg, P., Rasmussen, K.R., Uggerhøj, E. and Weyer, G. 2002

  7. Simulation of Flight-Type Engine Fan Noise in the NASA-Lewis 9X15 Anechoic Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Heidmann, M. F.; Dietrich, D. A.

    1976-01-01

    Flight type noise as contrasted to the usual ground static test noise exhibits substantial reductions in the time unsteadiness of tone noise, and in the mean level of tones calculated to be nonpropagating or cut-off. A model fan designed with cuttoff of the fundamental tone was acoustically tested in the anechoic wind tunnel under both static and tunnel flow conditions. The properties that characterize flight type noise were progressively simulated with increasing tunnel flow. The distinctly lobed directivity pattern of propagating rotor/stator interaction modes was also observed. Excess noise attributed to the ingestion of the flow disturbances that prevail near most static test facilities is substantially reduced with tunnel flow.

  8. The Denis-gruson Six-component Wind-tunnel Balance

    NASA Technical Reports Server (NTRS)

    1935-01-01

    The 6.C.1 balance is the first fully automatic balance assuring a continuous and simultaneous record of the aerodynamic characteristics of an airfoil in a wind tunnel. Because of the rapidity of the measurements a complete polar (six components) requires only about three minutes of wind, that is to say, of motive power, which is of interest for wind tunnels with high efficiency factors and may lead to the economical design of large size wind tunnels.

  9. Full Scale Wind Tunnel and Seaplane Tow Channel

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Construction progress, Full Scale entrance cone looking north, exit cone looking south, wind vanes north end, wind vanes north end of east return passage, wind vanes south end of west exit cone looking north east, wind vanes at south end of east exit cone looking north west, entrance cone looking south from north end. Full-Scale Tunnel (FST) entrance cone under construction. Smith DeFrance describes the entrance cone in NACA TR 459 as follows: 'The entrance cone is 75 feet in length and in this distance the cross section changes from a rectangle 72 by 110 feet to a 30 by 60 foot elliptic section. The area reduction in the entrance cone is slightly less than 5:1. The shape of the entrance cone was chosen to give as fas as possible a constant acceleration to the air stream and to retain a 9-foot length of nozzle for directing the flow.' (p. 293)

  10. Microdunes and other aeolian bedforms on Venus - Wind Tunnel simulations

    NASA Astrophysics Data System (ADS)

    Greeley, R.; Marshall, J. R.; Leach, R. N.

    1984-10-01

    The development of aeolian bedforms in the simulated Venusian environment has been experimentally studied in the Venus Wind Tunnel. It is found that the development of specific bedforms, including ripples, dunes, and 'waves', as well as their geometry, are controlled by a combination of factors including particle size, wind speed, and atmospheric density. Microdunes are formed which are analogous to full-size terrestrial dunes and are characterized by the development of slip faces, internal cross-bedding, a low ratio of saltation path length to dune length, and a lack of particle-size sorting. They begin to develop at wind speeds just above saltation threshold and evolve into waves at higher velocities. At wind speeds of about 1.5 m/sec and higher, the bed is flat and featureless. This evolution is explained by a model based on the interaction of alternating zones of erosion and deposition and particle saltation distances.

  11. Microdunes and Other Aeolian Bedforms on Venus: Wind Tunnel Simulations

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Marshall, J. R.; Leach, R. N.

    1985-01-01

    The development of aeolian bedforms in the simulated Venusian environment has been experimentally studied in the Venus Wind tunnel. It is found that the development of specific bedforms, including ripples, dunes, and waves, as well as their geometry, are controlled by a combination of factors including particle size, wind speed, and atmospheric density. Microdunes are formed which are analogous to full-size terrestrial dunes and are characterized by the development of slip faces, internal cross-bedding, a low ratio of saltation path length to dune length, and a lack of particle-size sorting. They begin to develop at wind speeds just above saltation threshold and evolve into waves at higher velocities. At wind speeds of about 1.5 m/sec and higher, the bed is flat and featureless. This evolution is explained by a model based on the interaction of alternating zones of erosion and deposition and particle saltation distances.

  12. Microdunes and other aeolian bedforms on Venus - Wind Tunnel simulations

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Marshall, J. R.; Leach, R. N.

    1984-01-01

    The development of aeolian bedforms in the simulated Venusian environment has been experimentally studied in the Venus Wind Tunnel. It is found that the development of specific bedforms, including ripples, dunes, and 'waves', as well as their geometry, are controlled by a combination of factors including particle size, wind speed, and atmospheric density. Microdunes are formed which are analogous to full-size terrestrial dunes and are characterized by the development of slip faces, internal cross-bedding, a low ratio of saltation path length to dune length, and a lack of particle-size sorting. They begin to develop at wind speeds just above saltation threshold and evolve into waves at higher velocities. At wind speeds of about 1.5 m/sec and higher, the bed is flat and featureless. This evolution is explained by a model based on the interaction of alternating zones of erosion and deposition and particle saltation distances.

  13. Propulsion simulation for magnetically suspended wind tunnel models

    NASA Technical Reports Server (NTRS)

    Joshi, Prakash B.; Beerman, Henry P.; Chen, James; Krech, Robert H.; Lintz, Andrew L.; Rosen, David I.

    1990-01-01

    The feasibility of simulating propulsion-induced aerodynamic effects on scaled aircraft models in wind tunnels employing Magnetic Suspension and Balance Systems. The investigation concerned itself with techniques of generating exhaust jets of appropriate characteristics. The objectives were to: (1) define thrust and mass flow requirements of jets; (2) evaluate techniques for generating propulsive gas within volume limitations imposed by magnetically-suspended models; (3) conduct simple diagnostic experiments for techniques involving new concepts; and (4) recommend experiments for demonstration of propulsion simulation techniques. Various techniques of generating exhaust jets of appropriate characteristics were evaluated on scaled aircraft models in wind tunnels with MSBS. Four concepts of remotely-operated propulsion simulators were examined. Three conceptual designs involving innovative adaptation of convenient technologies (compressed gas cylinders, liquid, and solid propellants) were developed. The fourth innovative concept, namely, the laser-assisted thruster, which can potentially simulate both inlet and exhaust flows, was found to require very high power levels for small thrust levels.

  14. Laminar flow test installation in the Boeing Research Wind Tunnel

    NASA Technical Reports Server (NTRS)

    George-Falvy, Dezso

    1990-01-01

    This paper describes the initial wind tunnels tests in the 5- by 8-ft Boeing Research Wind Tunnel of a near full-scale (20-foot chord) swept wing section having laminar flow control (LFC) by slot suction over its first 30 percent chord. The model and associated test apparatus were developed for use as a testbed for LFC-related experimentation in support of preliminary design studies done under contract with the National Aeronautics and Space Administration. This paper contains the description of the model and associated test apparatus as well as the results of the initial test series in which the proper functioning of the test installation was demonstrated and new data were obtained on the sensitivity of suction-controlled laminar flow to surface protuberances in the presence of crossflow due to sweep.

  15. Computers vs. wind tunnels for aerodynamic flow simulations

    NASA Technical Reports Server (NTRS)

    Chapman, D. R.; Mark, H.; Pirtle, M. W.

    1975-01-01

    It is pointed out that in other fields of computational physics, such as ballistics, celestial mechanics, and neutronics, computations have already displaced experiments as the principal means of obtaining dynamic simulations. In the case of aerodynamic investigations, the complexity of the computational work involved in solving the Navier-Stokes equations is the reason that such investigations rely currently mainly on wind-tunnel testing. However, because of inherent limitations of the wind-tunnel approach and economic considerations, it appears that at some time in the future aerodynamic studies will chiefly rely on computational flow data provided by the computer. Taking into account projected development trends, it is estimated that computers with the required capabilities for a solution of the complete viscous, time-dependent Navier-Stokes equations will be available in the mid-1980s.

  16. Rain and deicing experiments in a wind tunnel

    NASA Technical Reports Server (NTRS)

    Fasso, G.

    1983-01-01

    Comments on films of tests simulating rain and ice conditions in a wind tunnel are presented, with the aim of studying efficient methods of overcoming the adverse effects of rain and ice on aircraft. In the experiments, lifesize models and models of the Mirave 4 aircraft were used. The equipment used to simulate rain and ice is described. Different configurations of landing and takeoff under conditions of moderate or heavy rain at variable angles of incidence and of skipping and at velocities varying from 30 to 130 m/sec are reproduced in the wind tunnel. The risks of erosion of supersonic aircraft by the rain during the loitering and approach phases are discussed.

  17. Advanced optical position sensors for magnetically suspended wind tunnel models

    NASA Technical Reports Server (NTRS)

    Lafleur, S.

    1985-01-01

    A major concern to aerodynamicists has been the corruption of wind tunnel test data by model support structures, such as stings or struts. A technique for magnetically suspending wind tunnel models was considered by Tournier and Laurenceau (1957) in order to overcome this problem. This technique is now implemented with the aid of a Large Magnetic Suspension and Balance System (LMSBS) and advanced position sensors for measuring model attitude and position within the test section. Two different optical position sensors are discussed, taking into account a device based on the use of linear CCD arrays, and a device utilizing area CID cameras. Current techniques in image processing have been employed to develop target tracking algorithms capable of subpixel resolution for the sensors. The algorithms are discussed in detail, and some preliminary test results are reported.

  18. A low-density boundary-layer wind tunnel facility

    NASA Technical Reports Server (NTRS)

    White, B. R.

    1987-01-01

    This abstract describes a low-density wind-tunnel facility that was established at NASA Ames in order to aid interpretation and understanding of data received from the Mariner and Viking spacecraft through earth-based simulation. The wind tunnel is a boundary-layer type which is capable of operating over a range of air densities ranging from 0.01 to 1.24 kg/cu m, with the lower values being equivalent to the near-surface density of the planet Mars. Although the facility was developed for space and extraterrestrial simulation, it also can serve as a relatively large-scale, low-density aerodynamic test facility. A description of this unique test facility and some Pitot-tube and hot-wire anemometry data acquired in the facility are presented.

  19. Wind tunnel requirements for computational fluid dynamics code verification

    NASA Technical Reports Server (NTRS)

    Marvin, Joseph G.

    1987-01-01

    The role of experiment in the development of Computational Fluid Dynamics (CFD) for aerodynamic flow field prediction is discussed. Requirements for code verification from two sources that pace the development of CFD are described for: (1) development of adequate flow modeling, and (2) establishment of confidence in the use of CFD to predict complex flows. The types of data needed and their accuracy differs in detail and scope and leads to definite wind tunnel requirements. Examples of testing to assess and develop turbulence models, and to verify code development, are used to establish future wind tunnel testing requirements. Versatility, appropriate scale and speed range, accessibility for nonintrusive instrumentation, computerized data systems, and dedicated use for verification were among the more important requirements identified.

  20. Preparation of polystyrene microspheres for laser velocimetry in wind tunnels

    NASA Technical Reports Server (NTRS)

    Nichols, Cecil E., Jr.

    1987-01-01

    Laser Velocimetry (L/V) had made great strides in replacing intrusive devices for wind tunnel flow measurements. The weakness of the L/V has not been the L/V itself, but proper size seeding particles having known drag characteristics. For many Langley Wind Tunnel applications commercial polystyrene latex microspheres suspended in ethanol, injected through a fluid nozzle provides excellent seeding but was not used due to the high cost. This paper provides the instructions, procedures, and formulations for producing polystyrene latex monodisperse microspheres of 0.6, 1.0, 1.7, 2.0, and 2.7 micron diameters. These are presently being used at Langley Research Center as L/V seeding particles.

  1. Wind tunnel studies of gas dispersion over complex terrain

    NASA Astrophysics Data System (ADS)

    Michálek, Petr; Zacho, David

    2016-03-01

    Wind tunnel studies of gas dispersion over complex terrain model were performed in VZLU Prague. The terrain model with a ground-level emission source was mounted in a boundary layer wind tunnel. Flow and concentration field behind the source was measured. The model presented an area of the Liberec city, 9.0 × 2.4 km in full scale. The emission source was mounted at the position of a heating plant in the model centre and concentration field was measured using flame ionisation detectors. The experimental results will be used for validation and verification of a new computational dispersion model intended for use in case of accidents with dangerous gas leakages in selected areas in Czech Republic.

  2. An electronic scanner of pressure for wind tunnel models

    NASA Technical Reports Server (NTRS)

    Kauffman, Ronald C.; Coe, Charles F.

    1986-01-01

    An electronic scanner of pressure (ESOP) has been developed by NASA Ames Research Center for installation in wind tunnel models. An ESOP system consists of up to 20 pressure modules (PMs), each with 48 pressure transducers and a heater, an analog-to-digital (A/D) converter module, a microprocessor, a data controller, a monitor unit, a control and processing unit, and a heater controller. The PMs and the A/D converter module are sized to be installed in the models tested in the Ames Aerodynamics Division wind tunnels. A unique feature of the pressure module is the lack of moving parts such as a pneumatic switch used in other systems for in situ calibrations. This paper describes the ESOP system and the results of the initial testing of the system. The initial results indicate the system meets the original design goal of 0.15 percent accuracy.

  3. Advanced experimental techniques for transonic wind tunnels - Final lecture

    NASA Technical Reports Server (NTRS)

    Kilgore, Robert A.

    1987-01-01

    A philosophy of experimental techniques is presented, suggesting that in order to be successful, one should like what one does, have the right tools, stick to the job, avoid diversions, work hard, interact with people, be informed, keep it simple, be self sufficient, and strive for perfection. Sources of information, such as bibliographies, newsletters, technical reports, and technical contacts and meetings are recommended. It is pointed out that adaptive-wall test sections eliminate or reduce wall interference effects, and magnetic suspension and balance systems eliminate support-interference effects, while the problem of flow quality remains with all wind tunnels. It is predicted that in the future it will be possible to obtain wind tunnel results at the proper Reynolds number, and the effects of flow unsteadiness, wall interference, and support interference will be eliminated or greatly reduced.

  4. Wind-tunnel investigation of the OMAC canard configuration

    NASA Technical Reports Server (NTRS)

    Ingram, W. C.; Yip, L. P.; Cook, E. L.

    1986-01-01

    Wind-tunnel tests were conducted on a 0.175-scale model of the OMAC Laser 300 canard configuration in the NASA Langley 12-Foot Low-Speed Wind Tunnel to determine its low-speed high angel-of-attack aerodynamic characteristics. The Laser 300 is a general aviation turboprop pusher aircraft utilizing a canard configuration. The design incorporates a low forward wing and a high main wing with a leading-edge droop installed on the outboard panel and tip fins mounted on the wing tips. The model was tested over a range of -6 to 50-deg angle-of-attack and 20 to -20 deg sideslip. Static force and moment data were measured, and the longitudinal and lateral-directional characteristics were determined.

  5. Pratt & Whitney Two Dimensional HSR Nozzle Test in the NASA Lewis 9- By 15- Foot Low Speed Wind Tunnel: Aerodynamic Results

    NASA Technical Reports Server (NTRS)

    Wolter, John D.; Jones, Christopher W.

    1999-01-01

    This paper discusses a test that was conducted jointly by Pratt & Whitney Aircraft Engines and NASA Lewis Research Center. The test was conducted in NASA's 9- by 15-Foot Low Speed Wind Tunnel (9x15 LSWT). The test setup, methods, and aerodynamic results of this test are discussed. Acoustical results are discussed in a separate paper by J. Bridges and J. Marino.

  6. Problems associated with operations and measurement in cryogenic wind tunnels

    NASA Technical Reports Server (NTRS)

    Blanchard, A.; Delcourt, V.; Plazanet, M.

    1986-01-01

    Cryogenic wind tunnel T'3 under continuous blower operation has been the object of improvements and the installation of auxiliary equipment, dealing in particular with the enlargement of the liquid nitrogen injection reservoir and the hook-up to a fast data acquisition system. Following a brief description of the installation and its functioning, we present the main experimental techniques and the instrumentation used in the cryogenic environment.

  7. Progress towards large wind tunnel magnetic suspension and balance systems

    NASA Technical Reports Server (NTRS)

    Britcher, C. P.

    1984-01-01

    Recent developments and current research efforts leading towards realization of a large scale production wind tunnel Magnetic Suspension and Balance facility are reviewed. Progress has been made in the areas of model roll control, high angle-of-attack testing, digital system control, high magnetic moment superconducting solenoid model cores, and system failure tolerance. Formal design studies of large scale facilities have commenced and are continuing.

  8. Bar-Chart-Monitor System For Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Jung, Oscar

    1993-01-01

    Real-time monitor system provides bar-chart displays of significant operating parameters developed for National Full-Scale Aerodynamic Complex at Ames Research Center. Designed to gather and process sensory data on operating conditions of wind tunnels and models, and displays data for test engineers and technicians concerned with safety and validation of operating conditions. Bar-chart video monitor displays data in as many as 50 channels at maximum update rate of 2 Hz in format facilitating quick interpretation.

  9. Wind tunnel model surface gauge for measuring roughness

    NASA Technical Reports Server (NTRS)

    Vorburger, T. V.; Gilsinn, D. E.; Teague, E. C.; Giauque, C. H. W.; Scire, F. E.; Cao, L. X.

    1987-01-01

    The optical inspection of surface roughness research has proceeded along two different lines. First, research into a quantitative understanding of light scattering from metal surfaces and into the appropriate models to describe the surfaces themselves. Second, the development of a practical instrument for the measurement of rms roughness of high performance wind tunnel models with smooth finishes. The research is summarized, with emphasis on the second avenue of research.

  10. An isentropic compression heated Ludwieg tube transient wind tunnel

    NASA Technical Reports Server (NTRS)

    Magari, Patrick J.; Lagraff, John E.

    1988-01-01

    Syracuse University's Ludwieg tube with isentropic compression facility is a transient wind tunnel employing a piston drive that incorporates insentropic compression heating of the test gas located ahead of a piston. The facility is well-suited for experimental investigations concerning supersonic and subsonic vehicles over a wide range of pressures, Reynolds numbers, and temperatures; all three parameters can be almost independently controlled. Work at the facility currently includes wake-induced stagnation point heat transfer and supersonic boundary layer transition.

  11. Development of internal balances for cryogenic wind tunnels

    NASA Astrophysics Data System (ADS)

    Ewald, Bernd F. R.; Graewe, Eberhard

    Thermal effects in the strain gage balance, which has hampered the development of large cryogenic wind tunnels are considered. Approaches for dealing with two of these effects are outlined. The effect of apparent strain over the whole temperature range is minimized by a compensation of each individual gage. A novel arrangement of the axial force systems allows a correct separation of thermal effect and force measurement in spite of temperature gradients in the balance body.

  12. Application of data acquisition systems for on-line definition and control of wind tunnel shape

    NASA Technical Reports Server (NTRS)

    Wolf, S. W. D.

    1979-01-01

    Improvements in wind tunnel design to reduce test and flight discrepancies are analyzed. Flexible wall streamlining, criteria for tunnel streamlining, and error assessment are discussed. It is concluded that the concept of self-streamlining wind tunnels is suited for on-line computer control.

  13. Tactical Defenses Against Systematic Variation in Wind Tunnel Testing

    NASA Technical Reports Server (NTRS)

    DeLoach, Richard

    2002-01-01

    This paper examines the role of unexplained systematic variation on the reproducibility of wind tunnel test results. Sample means and variances estimated in the presence of systematic variations are shown to be susceptible to bias errors that are generally non-reproducible functions of those variations. Unless certain precautions are taken to defend against the effects of systematic variation, it is shown that experimental results can be difficult to duplicate and of dubious value for predicting system response with the highest precision or accuracy that could otherwise be achieved. Results are reported from an experiment designed to estimate how frequently systematic variations are in play in a representative wind tunnel experiment. These results suggest that significant systematic variation occurs frequently enough to cast doubts on the common assumption that sample observations can be reliably assumed to be independent. The consequences of ignoring correlation among observations induced by systematic variation are considered in some detail. Experimental tactics are described that defend against systematic variation. The effectiveness of these tactics is illustrated through computational experiments and real wind tunnel experimental results. Some tutorial information describes how to analyze experimental results that have been obtained using such quality assurance tactics.

  14. A short history of the European Transonic Wind Tunnel ETW

    NASA Astrophysics Data System (ADS)

    Green, John; Quest, Jürgen

    2011-07-01

    This paper is written as a contribution to the celebration of 50 years of Progress in Aerospace Sciences and of the centenary of the birth of its founder, Dietrich Küchemann. It reviews the evolution of the European Transonic Wind Tunnel, ETW, from early conceptual studies to its entry into service and its current capabilities and achievements. It traces the development, from the earliest days, of experimental aerodynamics and of the basic aerodynamic understanding that gave rise to the main periods of wind tunnel building before and after World War II. By about 1960, this activity appeared to have come to a natural halt. The paper gives an account of the role of Küchemann in arguing the need in 1968 for a further step in wind tunnel capability, to provide transonic testing at high Reynolds numbers. It describes his leading role in gaining acceptance of the concept, formulating the specification and promoting studies of alternative, radical design options for the co-operative European project that became ETW. The progress of ETW through design, construction, commissioning and into full operation is recorded. The paper discusses the many technical innovations that have been introduced in order to meet customer requirements in the challenging field of aerodynamic testing in a cryogenic environment and, finally, looks to the future and the further technical challenges that it holds.

  15. Variable Stiffness Spar Wind-Tunnel Model Development and Testing

    NASA Technical Reports Server (NTRS)

    Florance, James R.; Heeg, Jennifer; Spain, Charles V.; Ivanco, Thomas G.; Wieseman, Carol D.; Lively, Peter S.

    2004-01-01

    The concept of exploiting wing flexibility to improve aerodynamic performance was investigated in the wind tunnel by employing multiple control surfaces and by varying wing structural stiffness via a Variable Stiffness Spar (VSS) mechanism. High design loads compromised the VSS effectiveness because the aerodynamic wind-tunnel model was much stiffer than desired in order to meet the strength requirements. Results from tests of the model include stiffness and modal data, model deformation data, aerodynamic loads, static control surface derivatives, and fuselage standoff pressure data. Effects of the VSS on the stiffness and modal characteristics, lift curve slope, and control surface effectiveness are discussed. The VSS had the most effect on the rolling moment generated by the leading-edge outboard flap at subsonic speeds. The effects of the VSS for the other control surfaces and speed regimes were less. The difficulties encountered and the ability of the VSS to alter the aeroelastic characteristics of the wing emphasize the need for the development of improved design and construction methods for static aeroelastic models. The data collected and presented is valuable in terms of understanding static aeroelastic wind-tunnel model development.

  16. The use of wind tunnel facilities to estimate hydrodynamic data

    NASA Astrophysics Data System (ADS)

    Hoffmann, Kristoffer; Tophøj Rasmussen, Johannes; Hansen, Svend Ole; Reiso, Marit; Isaksen, Bjørn; Egeberg Aasland, Tale

    2016-03-01

    Experimental laboratory testing of vortex-induced structural oscillations in flowing water is an expensive and time-consuming procedure, and the testing of high Reynolds number flow regimes is complicated due to the requirement of either a large-scale or high-speed facility. In most cases, Reynolds number scaling effects are unavoidable, and these uncertainties have to be accounted for, usually by means of empirical rules-of-thumb. Instead of performing traditional hydrodynamic measurements, wind tunnel testing in an appropriately designed experimental setup may provide an alternative and much simpler and cheaper framework for estimating the structural behavior under water current and wave loading. Furthermore, the fluid velocities that can be obtained in a wind tunnel are substantially higher than in a water testing facility, thus decreasing the uncertainty from scaling effects. In a series of measurements, wind tunnel testing has been used to investigate the static response characteristics of a circular and a rectangular section model. Motivated by the wish to estimate the vortex-induced in-line vibration characteristics of a neutrally buoyant submerged marine structure, additional measurements on extremely lightweight, helium-filled circular section models were conducted in a dynamic setup. During the experiment campaign, the mass of the model was varied in order to investigate how the mass ratio influences the vibration amplitude. The results show good agreement with both aerodynamic and hydrodynamic experimental results documented in the literature.

  17. Contraction design for small low-speed wind tunnels

    NASA Technical Reports Server (NTRS)

    Bell, James H.; Mehta, Rabindra D.

    1988-01-01

    An iterative design procedure was developed for two- or three-dimensional contractions installed on small, low-speed wind tunnels. The procedure consists of first computing the potential flow field and hence the pressure distributions along the walls of a contraction of given size and shape using a three-dimensional numerical panel method. The pressure or velocity distributions are then fed into two-dimensional boundary layer codes to predict the behavior of the boundary layers along the walls. For small, low-speed contractions it is shown that the assumption of a laminar boundary layer originating from stagnation conditions at the contraction entry and remaining laminar throughout passage through the successful designs if justified. This hypothesis was confirmed by comparing the predicted boundary layer data at the contraction exit with measured data in existing wind tunnels. The measured boundary layer momentum thicknesses at the exit of four existing contractions, two of which were 3-D, were found to lie within 10 percent of the predicted values, with the predicted values generally lower. From the contraction wall shapes investigated, the one based on a fifth-order polynomial was selected for installation on a newly designed mixing layer wind tunnel.

  18. Contraction design for small low-speed wind tunnels

    NASA Technical Reports Server (NTRS)

    Bell, James H.; Mehta, Rabindra D.

    1988-01-01

    An iterative design procedure was developed for 2- or 3-dimensional contractions installed on small, low speed wind tunnels. The procedure consists of first computing the potential flow field and hence the pressure distributions along the walls of a contraction of given size and shape using a 3-dimensional numerical panel method. The pressure or velocity distributions are then fed into 2-dimensional boundary layer codes to predict the behavior of the boundary layers along the walls. For small, low speed contractions, it is shown that the assumption of a laminar boundary layer originating from stagnation conditions at the contraction entry and remaining laminar throughout passage through the successful designs is justified. This hypothesis was confirmed by comparing the predicted boundary layer data at the contraction exit with measured data in existing wind tunnels. The measured boundary layer momentum thicknesses at the exit of four existing contractions, two of which were 3-D, were found to lie within 10 percent of the predicted values, with the predicted values generally lower. From the contraction wall shapes investigated, the one based on a 5th order polynomial was selected for newly designed mixing wind tunnel installation.

  19. Ventilation of idealised urban area, LES and wind tunnel experiment

    NASA Astrophysics Data System (ADS)

    Kukačka, L.; Fuka, V.; Nosek, Š.; Kellnerová, R.; Jaňour, Z.

    2014-03-01

    In order to estimate the ventilation of vehicle pollution within street canyons, a wind tunnel experiment and a large eddy simulation (LES) was performed. A model of an idealised urban area with apartment houses arranged to courtyards was designed according to common Central European cities. In the wind tunnel, we assembled a set-up for simultaneous measurement of vertical velocity and tracer gas concentration. Due to the vehicle traffic emissions modelling, a new line source of tracer gas was designed and built into the model. As a computational model, the LES model solving the incompressible Navier-Stokes equations was used. In this paper, we focused on the street canyon with the line source situated perpendicular to an approach flow. Vertical and longitudinal velocity components of the flow with the pollutant concentration were obtained from two horizontal grids placed in different heights above the street canyon. Vertical advective and turbulent pollution fluxes were computed from the measured data as ventilation characteristics. Wind tunnel and LES data were qualitatively compared. A domination of advective pollution transport within the street canyon was determined. However, the turbulent transport with an opposite direction to the advective played a significant role within and above the street canyon.

  20. Hot-jet simulation in cryogenic wind tunnels

    NASA Technical Reports Server (NTRS)

    Asai, Keisuke

    1989-01-01

    In order to evaluate hot jet simulation capability in cryogenic wind tunnel testing, simple theoretical calculations were performed. The similarity parameters, isentropic flow properties, and normal shock relations were calculated for a variety of jet simulation techniques. The results were compared with those estimated for a full scale flight condition. It was shown that the cryogenic wind tunnel testing provides an opportunity for the most accurate hot jet simulation technique. By using a compressed nitrogen gas at ambient or moderately elevated temperatures as a jet gas, most all of the relevant similarity parameters including the jet temperature and velocity ratios and the Reynolds numbers, can be set to the full scale flight values. The only exception is the ratio of specific heats for jet flow. In an attempt to match the ratio of specific heats for the turbojet flow, gases other than pure nitrogen were considered. It was found that a nitrogen/methane mixture at moderately elevated temperature behaves like the real combustion gas. Using this mixture as a jet gas, complete simulation of the full scale turbojet exhaust becomes possible in cryogenic wind tunnels.

  1. Comparison of wind tunnel airfoil performance data with wind turbine blade data

    SciTech Connect

    Butterfield, C.P.; Scott, G.N.; Musial, W.

    1990-07-01

    Horizontal-axis wind turbine (HAWT) performance is usually predicted by using wind tunnel airfoil performance data in a blade element momentum theory analysis. This analysis assumes that the rotating blade airfoils will perform as they do in the wind tunnel. However, when HAWT performance is measured in full-scale operation, it is common to find that peak power levels are significantly greater than those predicted. This has led to empirical corrections to the predictions. Viterna and Corrigan proposed the most popular version of this correction. But very little insight has been gained into the basic cause of this discrepancy. The Solar Energy Research Institute (SERI), funded by the US Department of Energy (DOE), has conducted the first phase of an experiment focused on understanding the basic fluid mechanics of HWAT aerodynamics. Results to date have shown that unsteady aerodynamics exist during all operating conditions and dynamic stall can exist for high yaw angle operation. Stall hysteresis occurs even for small yaw angles, and delayed stall is a very persistent reality in all operating conditions. Delayed stall is the result of a leading-edge suction peak remaining attached through angles of attack (AOAs) up to 30{degree}. Wind tunnel results show this peak separating from the leading edge at 18{degree} AOA. The effect of this anomaly is to raise normal force coefficients and tangent force coefficients for high AOA. Increased tangent forces will directly for high AOA. Increased tangent forces will directly affect HAWT performance in high wind speed operation. This report describes pressure distribution data resulting from both wind tunnel and HAWT tests. A method of bins is used to average the HAWT data, which are compared to the wind tunnel data. The analysis technique and the test setup for each test are described. 10 refs., 15 figs.

  2. The steady-state flow quality in a model of a non-return wind tunnel

    NASA Technical Reports Server (NTRS)

    Mort, K. W.; Eckert, W. T.; Kelly, M. W.

    1972-01-01

    The structural cost of non-return wind tunnels is significantly less than that of the more conventional closed-circuit wind tunnels. However, because of the effects of external winds, the flow quality of non-return wind tunnels is an area of concern at the low test speeds required for V/STOL testing. The flow quality required at these low speeds is discussed and alternatives to the traditional manner of specifying the flow quality requirements in terms of dynamic pressure and angularity are suggested. The development of a non-return wind tunnel configuration which has good flow quality at low as well as at high test speeds is described.

  3. Aeolian transport of biota with dust: A wind tunnel experiment

    NASA Astrophysics Data System (ADS)

    Rivas, J. A., Jr.; Gill, T. E.; Van Pelt, R. S.; Walsh, E.

    2015-12-01

    Ephemeral wetlands are ideal sources for dust emission, as well as repositories for dormant stages of aquatic invertebrates. An important component of invertebrate dispersal and colonization to new areas is the ability to be entrained into the atmosphere. Aquatic invertebrate eggs fall within the size of dust and sand grains (30-600μm), are less dense and aerodynamically shaped. We have shown previously that aquatic invertebrates can be dispersed long distances in dust storms but the extent of transport of taxa based on diapausing egg size/morphology has not been investigated. Here, we control the wind erosion process in a wind tunnel to test entrainment of diapausing stages of brine shrimp, clam shrimp, tadpole shrimp, fairy shrimp, Daphnia, and the rotifers Brachionus plicatilis and B. calyciflorus into the air by saltation. Diapausing eggs were mixed with sterilized wind-erodible soil. The soil/egg mixture was moistened with distilled water and air dried to form a crust. Dust was generated in a wind tunnel by releasing sand grains that act as saltator material similar to wind-entrained natural sands. Maximum wind velocity was 10m/s and entrained particles were sampled through an isokinetic horizontal intake opening. Aeolian sediment was collected from three points in the system; transfer section for coarse sediment, the pan subtending a settling chamber for finer saltation-sized sediment, and two paper filters for suspension-sized sediment. Samples were then passed through 250 and 350 μm sieves to remove abrader sand and rehydrated with various sterile media depending on the type of organism. We retrieved viable brine, fairy, and tadpole shrimp, ostracods, Daphnia, and diapausing eggs of the rotifers after hydration. This experiment demonstrates that resting stages of many invertebrates can be wind-eroded due to size and egg morphology and remain viable under controlled conditions mimicking dust emission.

  4. Wind tunnel modeling of toxic gas releases at industrial facilities

    SciTech Connect

    Petersen, R.L.

    1994-12-31

    Government agencies and the petroleum, chemical and gas industries in the US and abroad have become increasingly concerned about the issues of toxic gas dispersal. Because of this concern, research programs have been sponsored by these various groups to improve the capabilities in hazard mitigation and response. Present computer models used to predict pollutant concentrations at industrial facilities do not properly account for the effects of structures. Structures can act to trap or deflect the cloud and modify the cloud dimensions, thereby possibly increasing or reducing downwind concentrations. The main purpose of this evaluation was to develop a hybrid modeling approach, which combines wind tunnel and dispersion modeling, to obtain more accurate concentration estimates when buildings or structures affect the dispersion of hazardous chemical vapors. To meet the study objectives, wind tunnel testing was performed on a building cluster typical of two industrial settings where accidental releases of toxic gases might occur. This data set was used to test the validity of the AFTOX and SLAB models for estimating concentrations and was used to develop and test two hybrid models. Two accident scenarios were simulated, an evaporating pool of a gas slightly heavier than air (Hydrazine-N{sub 2}H{sub 4}) and a liquid jet release of Nitrogen Tetroxide (N{sub 2}O{sub 4}) where dense gas dispersion effects would be significant. Tests were conducted for a range of wind directions and wind speeds for two different building configurations (low rise and high rise structures).

  5. Wind tunnel simulations of wind turbine wake interactions in neutral and stratified wind flow.

    NASA Astrophysics Data System (ADS)

    Hancock, P. E.; Pascheke, F.

    2010-09-01

    A second programme of work is about to commence as part of a further four years of funding for the UK-EPSRC SUPERGEN-Wind large-wind-farm consortium. The first part of the initial programme at Surrey was to establish and set up appropriate techniques for both on- and off-shore boundary layers (though with an emphasis on the latter) at a suitable scale, and to build suitable rotating model wind turbines. The EnFlo wind tunnel, a UK-NCAS special facility, is capable of creating scaled neutral, stable and unstable boundary layers in its 20m long working section. The model turbines are 1/300-scale of 5MW-size, speed controlled with phase-lock measurement capability, and the blade design takes into account low Reynolds-number effects. Velocity measurements are primarily made using two-component LDA, combined with a ‘cold-wire' probe in order to measure the local turbulent heat flux. Simulation of off-shore wakes is particularly constrained because i) at wind tunnel scale the inherently low surface roughness can be below that for fully rough conditions, ii) the power required to stratify the flow varies as the square of the flow speed, and could easily be impractically large, iii) low blade Reynolds number. The boundary layer simulations, set up to give near-equilibrium conditions in terms of streamwise development, and the model turbines have been designed against these constraints, but not all constraints can be always met simultaneously in practice. Most measurements so far have been made behind just one or two turbines in neutral off- and on-shore boundary layers, at stations up to 12 disk diameters downstream. These show how, for example, the wake of a turbine affects the development of the wake of a downwind turbine that is laterally off-set by say half or one diameter, and how the unaffected part from the first turbine merges with the affected wake of the second. As expected a lower level of atmospheric turbulence causes the wakes to develop and fill-in more

  6. Wind Tunnel Simulation of the Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Hohman, Tristen; Smits, Alexander; Martinelli, Luigi

    2013-11-01

    To simulate the interaction of large Vertical Axis Wind Turbines (VAWT) with the Atmospheric Boundary Layer (ABL) in the laboratory, we implement a variant of Counihan's technique [Counihan 1969] in which a combination of a castellated barrier, elliptical vortex generators, and floor roughness elements is used to create an artificial ABL profile in a standard closed loop wind tunnel. To examine the development and formation of the artificial ABL hotwire and SPIV measurements were taken at various downstream locations with changes in wall roughness, wall type, and vortex generator arrangements. It was found possible to generate a boundary layer at Reθ ~106 , with a mean velocity that followed the 1/7 power law of a neutral ABL over rural terrain and longitudinal turbulence intensities and power spectra that compare well with the data obtained for high Reynolds number flat plate turbulent boundary layers [Hultmark et al. 2010]. Supported by Hopewell Wind Power Ltd., and the Princeton Grand Challenges Program.

  7. Wind Tunnel Simulation of the Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Hohman, Tristen; Smits, Alexander; Martinelli, Luigi

    2012-11-01

    To simulate the interaction of large Vertical Axis Wind Turbines (VAWT) with the Atmospheric Boundary Layer (ABL) in the laboratory, we implement a variant of Counihan's technique in which a combination of a castellated barrier, elliptical vortex generators, and floor roughness elements is used to create an artificial ABL profile in a standard closed loop wind tunnel. We report hotwire measurements in a plane normal to the flow direction at various downstream positions and free stream velocities to examine the development and formation of the artificial ABL. It was found possible to generate a boundary layer at Reθ ~106 , with a mean velocity that followed the 1/7 power law of a neutral ABL over rural terrain and longitudinal turbulence intensities and power spectra that compare well with the data obtained by Hultmark in 2010 for high Reynolds number flat plate turbulent boundary layers. Supported by Hopewell Wind Power Ltd., and the Princeton Grand Challenges Program.

  8. Wind tunnel test of the S814 thick root airfoil

    SciTech Connect

    Somers, D.M.; Tangler, J.L.

    1996-11-01

    The objective of this wind-tunnel test was to verify the predictions of the Eppler Airfoil Design and Analysis Code for a very thick airfoil having a high maximum lift coefficient designed to be largely insensitive to leading-edge roughness effects. The 24 percent thick S814 airfoil was designed with these characteristics to accommodate aerodynamic and structural considerations for the root region of a wind-turbine blade. In addition, the airfoil`s maximum lift-to-drag ratio was designed to occur at a high lift coefficient. To accomplish the objective, a two-dimensional wind tunnel test of the S814 thick root airfoil was conducted in January 1994 in the low-turbulence wind tunnel of the Delft University of Technology Low Speed Laboratory, The Netherlands. Data were obtained with transition free and transition fixed for Reynolds numbers of 0.7, 1.0, 1.5, 2.0, and 3.0 {times} 10{sup 6}. For the design Reynolds number of 1.5 {times} 10{sup 6}, the maximum lift coefficient with transition free is 1.32, which satisfies the design specification. However, this value is significantly lower than the predicted maximum lift coefficient of almost 1.6. With transition fixed at the leading edge, the maximum lift coefficient is 1.22. The small difference in maximum lift coefficient between the transition-free and transition-fixed conditions demonstrates the airfoil`s minimal sensitivity to roughness effects. The S814 root airfoil was designed to complement existing NREL low maximum-lift-coefficient tip-region airfoils for rotor blades 10 to 15 meters in length.

  9. The Resistance of Spheres in Wind Tunnels and In Air

    NASA Technical Reports Server (NTRS)

    Bacon, D L; Reid, E G

    1924-01-01

    To supplement the standardization tests now in progress at several laboratories, a broad investigation of the resistance of spheres in wind tunnels and free air has been carried out by the National Advisory Committee for Aeronautics. The subject has been classed in aerodynamic research, and in consequence there is available a great mass of data from previous investigations. This material was given careful consideration in laying out the research, and explanation of practically all the disagreement between former experiments has resulted. A satisfactory confirmation of Reynolds law has been accomplished, the effect of means of support determined, the range of experiment greatly extended by work in the new variable density wind tunnel, and the effects of turbulence investigated by work in the tunnels and by towing and dropping tests in free air. It is concluded that the erratic nature of most of the previous work is due to support interference and differing turbulence conditions. While the question of support has been investigated thoroughly, a systematic and comprehensive study of the effects of scale and quality of turbulence will be necessary to complete the problem, as this phase was given only general treatment.

  10. An experimental study of an adaptive-wall wind tunnel

    NASA Technical Reports Server (NTRS)

    Celik, Zeki; Roberts, Leonard

    1988-01-01

    A series of adaptive wall ventilated wind tunnel experiments was carried out to demonstrate the feasibility of using the side wall pressure distribution as the flow variable for the assessment of compatibility with free air conditions. Iterative and one step convergence methods were applied using the streamwise velocity component, the side wall pressure distribution and the normal velocity component in order to investigate their relative merits. The advantage of using the side wall pressure as the flow variable is to reduce the data taking time which is one the major contributors to the total testing time. In ventilated adaptive wall wind tunnel testing, side wall pressure measurements require simple instrumentation as opposed to the Laser Doppler Velocimetry used to measure the velocity components. In ventilated adaptive wall tunnel testing, influence coefficients are required to determine the pressure corrections in the plenum compartment. Experiments were carried out to evaluate the influence coefficients from side wall pressure distributions, and from streamwise and normal velocity distributions at two control levels. Velocity measurements were made using a two component Laser Doppler Velocimeter system.

  11. The active flexible wing aeroservoelastic wind-tunnel test program

    NASA Technical Reports Server (NTRS)

    Noll, Thomas; Perry, Boyd

    1989-01-01

    For a specific application of aeroservoelastic technology, Rockwell International Corporation developed a concept known as the Active Flexible Wing (AFW). The concept incorporates multiple active leading-and trailing-edge control surfaces with a very flexible wing such that wing shape is varied in an optimum manner resulting in improved performance and reduced weight. As a result of a cooperative program between the AFWAL's Flight Dynamics Laboratory, Rockwell, and NASA LaRC, a scaled aeroelastic wind-tunnel model of an advanced fighter was designed, fabricated, and tested in the NASA LaRC Transonic Dynamics Tunnel (TDT) to validate the AFW concept. Besides conducting the wind-tunnel tests NASA provided a design of an Active Roll Control (ARC) System that was implemented and evaluated during the tests. The ARC system used a concept referred to as Control Law Parameterization which involves maintaining constant performance, robustness, and stability while using different combinations of multiple control surface displacements. Since the ARC system used measured control surface stability derivatives during the design, the predicted performance and stability results correlated very well with test measurements.

  12. Materials and construction techniques for cryogenic wind tunnel facilities for instruction/research use

    NASA Technical Reports Server (NTRS)

    Morse, S. F.; Roper, A. T.

    1975-01-01

    The results of the cryogenic wind tunnel program conducted at NASA Langley Research Center are presented to provide a starting point for the design of an instructional/research wind tunnel facility. The advantages of the cryogenic concept are discussed, and operating envelopes for a representative facility are presented to indicate the range and mode of operation. Special attention is given to the design, construction and materials problems peculiar to cryogenic wind tunnels. The control system for operation of a cryogenic tunnel is considered, and a portion of a linearized mathematical model is developed for determining the tunnel dynamic characteristics.

  13. Detailed Uncertainty Analysis for Ares I Ascent Aerodynamics Wind Tunnel Database

    NASA Technical Reports Server (NTRS)

    Hemsch, Michael J.; Hanke, Jeremy L.; Walker, Eric L.; Houlden, Heather P.

    2008-01-01

    A detailed uncertainty analysis for the Ares I ascent aero 6-DOF wind tunnel database is described. While the database itself is determined using only the test results for the latest configuration, the data used for the uncertainty analysis comes from four tests on two different configurations at the Boeing Polysonic Wind Tunnel in St. Louis and the Unitary Plan Wind Tunnel at NASA Langley Research Center. Four major error sources are considered: (1) systematic errors from the balance calibration curve fits and model + balance installation, (2) run-to-run repeatability, (3) boundary-layer transition fixing, and (4) tunnel-to-tunnel reproducibility.

  14. Tests of models equipped with TPS in low speed ONERA F1 pressurized wind tunnel

    NASA Astrophysics Data System (ADS)

    Leynaert, J.

    1992-09-01

    The particular conditions of tests of models equipped with a turbofan powered simulator (TPS) at high Reynolds numbers in a pressurized wind tunnel are presented. The high-pressure air supply system of the wind tunnel, the equipment of the balance with the high-pressure traversing flow and its calibration, and the thrust calibration method of the TPS and its verification in the wind tunnel are described.

  15. Wind tunnel simulation of a wind turbine wake in neutral, stable and unstable wind flow

    NASA Astrophysics Data System (ADS)

    Hancock, P. E.; Zhang, S.; Pascheke, F.; Hayden, P.

    2014-12-01

    Measurements of mean velocity, Reynolds stresses, temperature and heat flux have been made in the wake of a model wind turbine in the EnFlo meteorology wind tunnel, for three atmospheric boundary layer states: the base-line neutral case, stable and unstable. The full-to-model scale is approximately 300:1. Primary instrumentation is two-component LDA combine with cold-wire thermometry to measure heat flux. In terms of surface conditions, the stratified cases are weak, but there is a strong 'imposed' condition in the stable case. The measurements were made between 0.5D and 10D, where D is the turbine disk diameter. In the stable case the velocity deficit decreases more slowly; more quickly in the unstable case. Heights at which quantities are maximum or minimum are greater in the unstable case and smaller in the stable case. In the stable case the wake height is suppressed but the width is increased, while in the unstable case the height is increased and the width (at hub height) reaches a maximum and then decreases. The turbulence in the wake behaves in a complex way. Further work needs to be done, to cover stronger levels of surface condition, requiring more extensive measurements to properly capture the wake development.

  16. Full-scale S-76 rotor performance and loads at low speeds in the NASA Ames 80- by 120-Foot Wind Tunnel. Vol. 1

    NASA Technical Reports Server (NTRS)

    Shinoda, Patrick M.

    1996-01-01

    A full-scale helicopter rotor test was conducted in the NASA Ames 80- by 120-Foot Wind Tunnel with a four-bladed S-76 rotor system. Rotor performance and loads data were obtained over a wide range of rotor shaft angles-of-attack and thrust conditions at tunnel speeds ranging from 0 to 100 kt. The primary objectives of this test were (1) to acquire forward flight rotor performance and loads data for comparison with analytical results; (2) to acquire S-76 forward flight rotor performance data in the 80- by 120-Foot Wind Tunnel to compare with existing full-scale 40- by 80-Foot Wind Tunnel test data that were acquired in 1977; (3) to evaluate the acoustic capability of the 80- by 120- Foot Wind Tunnel for acquiring blade vortex interaction (BVI) noise in the low speed range and compare BVI noise with in-flight test data; and (4) to evaluate the capability of the 80- by 120-Foot Wind Tunnel test section as a hover facility. The secondary objectives were (1) to evaluate rotor inflow and wake effects (variations in tunnel speed, shaft angle, and thrust condition) on wind tunnel test section wall and floor pressures; (2) to establish the criteria for the definition of flow breakdown (condition where wall corrections are no longer valid) for this size rotor and wind tunnel cross-sectional area; and (3) to evaluate the wide-field shadowgraph technique for visualizing full-scale rotor wakes. This data base of rotor performance and loads can be used for analytical and experimental comparison studies for full-scale, four-bladed, fully articulated rotor systems. Rotor performance and structural loads data are presented in this report.

  17. Description and calibration of the Langley unitary plan wind tunnel

    NASA Technical Reports Server (NTRS)

    Jackson, C. M., Jr.; Corlett, W. A.; Monta, W. J.

    1981-01-01

    The two test sections of the Langley Unitary Plan Wind Tunnel were calibrated over the operating Mach number range from 1.47 to 4.63. The results of the calibration are presented along with a a description of the facility and its operational capability. The calibrations include Mach number and flow angularity distributions in both test sections at selected Mach numbers and tunnel stagnation pressures. Calibration data are also presented on turbulence, test-section boundary layer characteristics, moisture effects, blockage, and stagnation-temperature distributions. The facility is described in detail including dimensions and capacities where appropriate, and example of special test capabilities are presented. The operating parameters are fully defined and the power consumption characteristics are discussed.

  18. Transonic wind-tunnel tests of a lifting parachute model

    NASA Technical Reports Server (NTRS)

    Foughner, J. T., Jr.; Reed, J. F.; Wynne, E. C.

    1976-01-01

    Wind-tunnel tests have been made in the Langley transonic dynamics tunnel on a 0.25-scale model of Sandia Laboratories' 3.96-meter (13-foot), slanted ribbon design, lifting parachute. The lifting parachute is the first stage of a proposed two-stage payload delivery system. The lifting parachute model was attached to a forebody representing the payload. The forebody was designed and installed in the test section in a manner which allowed rotational freedom about the pitch and yaw axes. Values of parachute axial force coefficient, rolling moment coefficient, and payload trim angles in pitch and yaw are presented through the transonic speed range. Data are presented for the parachute in both the reefed and full open conditions. Time history records of lifting parachute deployment and disreefing tests are included.

  19. An isentropic compression-heated Ludweig tube transient wind tunnel

    NASA Technical Reports Server (NTRS)

    Magari, Patrick J.; Lagraff, John E.

    1991-01-01

    Theoretical development and experimental results show that the Ludweig tube with isentropic heating (LICH) transient wind tunnel described is a viable means of producing flow conditions that are suitable for a variety of experimental investigations. A complete analysis of the wave dynamics of the pump tube compression process is presented. The LICH tube operating conditions are very steady and run times are greater than those of other types of transient facilities such as shock tubes and gas tunnels. This facility is well suited for producing flow conditions that are dynamically similar to those found in a gas turbine, i.e., transonic Mach number, gas-to-wall temperature ratios of about 1.5, and Reynolds numbers greater than 10 to the 6th.

  20. An isentropic compression-heated Ludweig tube transient wind tunnel

    SciTech Connect

    Magari, P.J.; Lagraff, J.E. )

    1991-05-01

    Theoretical development and experimental results show that the Ludweig tube with isentropic heating (LICH) transient wind tunnel described is a viable means of producing flow conditions that are suitable for a variety of experimental investigations. A complete analysis of the wave dynamics of the pump tube compression process is presented. The LICH tube operating conditions are very steady and run times are greater than those of other types of transient facilities such as shock tubes and gas tunnels. This facility is well suited for producing flow conditions that are dynamically similar to those found in a gas turbine, i.e., transonic Mach number, gas-to-wall temperature ratios of about 1.5, and Reynolds numbers greater than 10 to the 6th. 15 refs.

  1. Flow quality studies of the NASA Lewis Research Center 8- by 6-foot supersonic/9- by 15-foot Low Speed Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Arrington, E. A.; Pickett, Mark T.

    1992-01-01

    A series of studies were conducted to determine the existing flow quality in the NASA Lewis 8 by 6 Foot Supersonic/9 by 15 Foot Low Speed Wind Tunnel. The information gathered from these studies was used to determine the types and designs of flow manipulators which can be installed to improve overall tunnel flow quality and efficiency. Such manipulators include honeycomb flow straighteners, turbulence reduction screens, corner turning vanes, and acoustic treatments. The types of measurements, instrumentation, and results obtained from experiments conducted at several locations throughout the tunnel loop are described.

  2. Flow quality studies of the NASA Lewis Research Center 8- by 6-foot supersonic/9- by 15-foot low speed wind tunnel

    NASA Technical Reports Server (NTRS)

    Arrington, E. Allen; Pickett, Mark T.

    1992-01-01

    A series of studies were conducted to determine the existing flow quality in the NASA Lewis 8 by 6 Foot Supersonic/9 by 15 Foot Low speed Wind Tunnel. The information gathered from these studies was used to determine the types and designs of flow manipulators which can be installed to improve overall tunnel flow quality and efficiency. Such manipulators include honeycomb flow straighteners, turbulence reduction screens, corner turning vanes, and acoustic treatments. The types of measurements, instrumentation, and results obtained from experiments conducted at several locations throughout the tunnel loop are described.

  3. Comparison of options for reduction of noise in the test section of the NASA Langley 4x7m wind tunnel, including reduction of nozzle area

    NASA Technical Reports Server (NTRS)

    Hayden, R. E.

    1984-01-01

    The acoustically significant features of the NASA 4X7m wind tunnel and the Dutch-German DNW low speed tunnel are compared to illustrate the reasons for large differences in background noise in the open jet test sections of the two tunnels. Also introduced is the concept of reducing test section noise levels through fan and turning vane source reductions which can be brought about by reducing the nozzle cross sectional area, and thus the circuit mass flow for a particular exit velocity. The costs and benefits of treating sources, paths, and changing nozzle geometry are reviewed.

  4. Practical application of RINO, a smartphone-based dynamic displacement sensing application for wind tunnel tests

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Woo; Jeong, Jong-Hyun; Knez, Kyle P.; Min, Jae-Hong; Jo, Hongki

    2016-04-01

    Dynamic displacement is one of the most important measurands in wind tunnel tests of structures. Laser sensors or optical sensors are usually used in wind tunnel tests to measure displacements. However, these commercial sensors have limitations in its use, cost and installation despite of their good performance in accuracy. RINO (Real-time Image- processing for Non-contact monitoring), an iOS software application for dynamic displacement monitoring, has been developed in the previous study. In this study, feasibility of RINO in practical use for wind tunnel tests is explored. Series of wind tunnel tests show that performances of RINO are comparable with those of conventional displacement sensors.

  5. Automation&Characterization of US Air Force Bench Top Wind Tunnels - Summary Report

    SciTech Connect

    Hardy, J.E.

    2006-03-23

    The United States Air Force Precision Measurement Equipment Laboratories (PMEL) calibrate over 1,000 anemometer probes per year. To facilitate a more efficient calibration process for probe-style anemometers, the Air Force Metrology and Calibration Program underwent an effort to modernize the existing PMEL bench top wind tunnels. Through a joint effort with the Department of Energy's Oak Ridge National Laboratory, the performance of PMEL wind tunnels was improved. The improvement consisted of new high accuracy sensors, automatic data acquisition, and a software-driven calibration process. As part of the wind tunnel upgrades, an uncertainty analysis was completed, laser Doppler velocimeter profiling was conducted to characterize the velocities at probe locations in the wind tunnel, and pitot tube calibrations of the wind tunnel were verified. The bench top wind tunnel accuracy and repeatability has been measured for nine prototype wind tunnel systems and valuable field experience has been gained with these wind tunnels at the PMELs. This report describes the requirements for the wind tunnel improvements along with actual implementation strategies and details. Lessons-learned from the automation, the velocity profiling, and the software-driven calibration process will also be discussed.

  6. A remote millivolt multiplexer and amplifier module for wind tunnel data acquisition

    NASA Technical Reports Server (NTRS)

    Juanarena, D. B.; Blumenthal, P. Z.

    1982-01-01

    A 30-channel remotely located multiplexer and amplifier module is developed for the measurement of wind tunnel models, which substantially reduces the amount of wiring necessary and thus provides higher accuracy. The module provides for a wide variety of transducer voltage outputs to be multiplexed and amplified within the model, and all signals are able to exit the module on two wires. The module is self-calibrating, and when coupled with the electronically scanned pressure instrumentation widely used in wind tunnels, it allows the modular wind tunnel models to be fabricated and checked before installation into the wind tunnel.

  7. CFD and experimental data of closed-loop wind tunnel flow.

    PubMed

    Calautit, John Kaiser; Hughes, Ben Richard

    2016-06-01

    The data presented in this article were the basis for the study reported in the research articles entitled 'A validated design methodology for a closed loop subsonic wind tunnel' (Calautit et al., 2014) [1], which presented a systematic investigation into the design, simulation and analysis of flow parameters in a wind tunnel using Computational Fluid Dynamics (CFD). The authors evaluated the accuracy of replicating the flow characteristics for which the wind tunnel was designed using numerical simulation. Here, we detail the numerical and experimental set-up for the analysis of the closed-loop subsonic wind tunnel with an empty test section. PMID:26958641

  8. Tests of a protective shell passive release mechanism for hypersonic wind-tunnel models

    NASA Technical Reports Server (NTRS)

    Puster, R. L.; Dunn, J. E.

    1979-01-01

    A protective shell mechanism for wind tunnel models was developed and tested. The mechanism is passive in operation, reliable, and imposes no new structural design changes for wind tunnel models. Methods of predicting the release time and the measured loads associated with the release of the shell are given. The mechanism was tested in a series of wind tunnel tests to validate the removal process and measure the pressure loads on the model. The protective shell can be used for wind tunnel models that require a step input of heating and loading such as a thin skin heat transfer model. The mechanism may have other potential applications.

  9. Full Scale Wind Tunnel and Seaplane Tow Channel

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Construction progress, Full Scale exit cone looking south from entrance cone, east switchboard, west switchboard, wind vanes at north end looking north through entrance cone, north end looking south through entrance cone, entrance cone looking north from exit cone, wind vanes south end of west exit cone, wind vanes south end of east exit cone, Tow Channel trolley lines looking north, east and west incline braces at north end. Full-Scale Tunnel (FST) exit cone construction and installation of fan motors. Smith DeFrance describes the entrance cone in NACA TR 459 as follows: 'Forward of the propellers and located on the center line of the tunnel is a smooth fairing which transforms the somewhat elliptic section of the single passage into two circular ones at the propellers. From the propellers aft, the exit cone is divided into two passages and each transforms in the length of 132 feet from a 35-foot 61/2-inch circular section to a 46-foot square. The included angle between the sides of each passage is 6 inches.' (p. 293)

  10. Soil erosion rates caused by wind and saltating sand stresses in a wind tunnel

    SciTech Connect

    Ligotke, M.W.

    1993-02-01

    Wind erosion tests were performed in a wind tunnel in support of the development of long-term protective barriers to cap stabilized waste sites at the Hanford Site. Controlled wind and saltating sand erosive stresses were applied to physical models of barrier surface layers to simulate worst-case eolian erosive stresses. The goal of these tests was to provide information useful to the design and evaluation of the surface layer composition of an arid-region waste site barrier concept that incorporates a deep fine-soil reservoir. A surface layer composition is needed that will form an armor resistant to eolian erosion during periods of extreme dry climatic conditions, especially when such conditions result in the elimination or reduction of vegetation by water deprivation or wildfire. Because of the life span required of Hanford waste barriers, it is important that additional work follow these wind tunnel studies. A modeling effort is planned to aid the interpretation of test results with respect to the suitability of pea gravel to protect the finite-soil reservoir during long periods of climatic stress. It is additionally recommended that wind tunnel tests be continued and field data be obtained at prototype or actual barrier sites. Results wig contribute to barrier design efforts and provide confidence in the design of long-term waste site caps for and regions.

  11. Solar wind driven dust acoustic instability with Lorentzian kappa distribution

    SciTech Connect

    Arshad, Kashif; Ehsan, Zahida; Khan, S. A.; Mahmood, S.

    2014-02-15

    In a three species electron-ion-dust plasma following a generalized non-Maxwellian distribution function (Lorentzian or kappa), it is shown that a kinetic instability of dust-acoustic mode exists. The instability threshold is affected when such (quasineutral) plasma permeates through another static plasma. Such case is of interest when the solar wind is streaming through the cometary plasma in the presence of interstellar dust. In the limits of phase velocity of the waves larger and smaller than the thermal velocity of dust particles, the dispersion properties and growth rate of dust-acoustic mode are investigated analytically with validation via numerical analysis.

  12. Explicit mapping of acoustic regimes for wind instruments

    NASA Astrophysics Data System (ADS)

    Missoum, Samy; Vergez, Christophe; Doc, Jean-Baptiste

    2014-09-01

    This paper proposes a methodology to map the various acoustic regimes of wind instruments. The maps can be generated in a multidimensional space consisting of design, control parameters, and initial conditions. The boundaries of the maps are obtained explicitly in terms of the parameters using a Support Vector Machine (SVM) classifier as well as a dedicated adaptive sampling scheme. The approach is demonstrated on a simplified clarinet model for which several maps are generated based on different criteria. Examples of computation of the probability of occurrence of a specific acoustic regime are also provided. In addition, the approach is demonstrated on a design optimization example for optimal intonation.

  13. Two dimensional aerodynamic interference effects on oscillating airfoils with flaps in ventilated subsonic wind tunnels. [computational fluid dynamics

    NASA Technical Reports Server (NTRS)

    Fromme, J.; Golberg, M.; Werth, J.

    1979-01-01

    The numerical computation of unsteady airloads acting upon thin airfoils with multiple leading and trailing-edge controls in two-dimensional ventilated subsonic wind tunnels is studied. The foundation of the computational method is strengthened with a new and more powerful mathematical existence and convergence theory for solving Cauchy singular integral equations of the first kind, and the method of convergence acceleration by extrapolation to the limit is introduced to analyze airfoils with flaps. New results are presented for steady and unsteady flow, including the effect of acoustic resonance between ventilated wind-tunnel walls and airfoils with oscillating flaps. The computer program TWODI is available for general use and a complete set of instructions is provided.

  14. Water tunnel flow visualization and wind tunnel data analysis of the F/A-18. [leading edge extension vortex effects

    NASA Technical Reports Server (NTRS)

    Erickson, G. E.

    1982-01-01

    Six degree of freedom studies were utilized to extract a band of yawing and rolling moment coefficients from the F/A-18 aircraft flight records. These were compared with 0.06 scale model data obtained in a 16T wind tunnel facility. The results, indicate the flight test yawing moment data exhibit an improvement over the wind tunnel data to near neutral stability and a significant reduction in lateral stability (again to anear neutral level). These data are consistent with the flight test results since the motion was characterized by a relatively slo departure. Flight tests repeated the slow yaw departure at M 0.3. Only 0.16 scale model wind tunnel data showed levels of lateral stability similar to the flight test results. Accordingly, geometric modifications were investigated on the 0.16 scale model in the 30x60 foot wind tunnel to improve high angle of attack lateral stability.

  15. Enabling Advanced Wind-Tunnel Research Methods Using the NASA Langley 12-Foot Low Speed Tunnel

    NASA Technical Reports Server (NTRS)

    Busan, Ronald C.; Rothhaar, Paul M.; Croom, Mark A.; Murphy, Patrick C.; Grafton, Sue B.; O-Neal, Anthony W.

    2014-01-01

    Design of Experiment (DOE) testing methods were used to gather wind tunnel data characterizing the aerodynamic and propulsion forces and moments acting on a complex vehicle configuration with 10 motor-driven propellers, 9 control surfaces, a tilt wing, and a tilt tail. This paper describes the potential benefits and practical implications of using DOE methods for wind tunnel testing - with an emphasis on describing how it can affect model hardware, facility hardware, and software for control and data acquisition. With up to 23 independent variables (19 model and 2 tunnel) for some vehicle configurations, this recent test also provides an excellent example of using DOE methods to assess critical coupling effects in a reasonable timeframe for complex vehicle configurations. Results for an exploratory test using conventional angle of attack sweeps to assess aerodynamic hysteresis is summarized, and DOE results are presented for an exploratory test used to set the data sampling time for the overall test. DOE results are also shown for one production test characterizing normal force in the Cruise mode for the vehicle.

  16. Application of intelligent systems to wind tunnel test facilities

    NASA Technical Reports Server (NTRS)

    Lo, Ching F.; Steinle, Frank W., Jr.

    1988-01-01

    An approach to the application of intelligent-systems technology to the wind tunnel facilities at NASA Ames Research Center is outlined. To help fulfill the long-range goals of improving data quality and increasing personnel efficiency and management effectiveness, three major areas of intelligent systems application are recommended. The available state-of-the-art technology for developing the proposed systems is reviewed including the application of commercial software packages. The initial tasks and effort to develop these systems are recommended. A prototype expert system for selection of internal strain-gage balances has been built and is presented herein as an example model for the future systems.

  17. Wind tunnel tests of four flexible wing ultralight gliders

    NASA Technical Reports Server (NTRS)

    Ormiston, R. A.

    1979-01-01

    The aerodynamic lift, drag, and pitching moment characteristics of four full scale, flexible wing, ultralight gliders were measured in the settling chamber of a low speed wind tunnel. The gliders were tested over a wide range of angle of attack and at two different velocities. Particular attention was devoted to the lift and pitching moment behavior at low and negative angles of attack because of the potential loss of longitudinal stability of flexible wing gliders in this regime. The test results were used to estimate the performance and longitudinal control characteristics of the gliders.

  18. Infrared radiometer for measuring thermophysical properties of wind tunnel models

    NASA Technical Reports Server (NTRS)

    Corwin, R. R.; Moorman, S. L.; Becker, E. C.

    1978-01-01

    An infrared radiometer is described which was developed to measure temperature rises of wind tunnel models undergoing transient heating over a temperature range of -17.8 C to 260 C. This radiometer interfaces directly with a system which measures the effective thermophysical property square root of rho ck. It has an output temperature fluctuation of 0.26 C at low temperatures and 0.07 C at high temperatures, and the output frequency response of the radiometer is from dc to 400 hertz.

  19. Digital Control System For Wind-Tunnel Model

    NASA Technical Reports Server (NTRS)

    Hoadley, Sherwood T.; Mcgraw, Sandra

    1995-01-01

    Multiple functions performed by multiple coordinated processors for real-time control. Multiple input, multiple-output, multiple-function digital control system developed for wind-tunnel model of advanced fighter airplane with actively controlled flexible wings. Digital control system provides flexibility in selection of control laws, sensors, and actuators, plus some redundancy to accommodate failures in some of its subsystems. Implements feedback control scheme providing simultaneously for suppression of flutter, control of roll angle, roll-rate tracking during maximized roll maneuvers, and alleviation of loads during roll maneuvers.

  20. The F2 wind tunnel at Fauga-Mauzac

    NASA Technical Reports Server (NTRS)

    Afchain, D.; Broussaud, P.; Frugier, M.; Rancarani, G.

    1984-01-01

    Details on the French subsonic wind-tunnel F2 that becomes operational on July 1983 are presented. Some of the requirements were: (1) installation of models on any wall of the facility, (2) good observation points due to transparent walls, (3) smooth flow, (4) a laser velocimeter, and (5) easy access and handling. The characteristics include a nonpressurized return circuit, dimensions of 5 x 1.4 x 1.8 m, maximum velocity of 100 m/s and a variable speed fan of 683 kW.

  1. Wind-tunnel Tests of a Cyclogiro Rotor

    NASA Technical Reports Server (NTRS)

    Wheatley, John B; Windler, Ray

    1935-01-01

    During an extensive study of all types of rotating wings, the NACA examined the cyclogiro rotor and made an aerodynamic analysis of that system (reference 1). The examination disclosed that such a machine had sufficient promise to justify an experimental investigation; a model with a diameter and span of 8 feet was therefore constructed and tested in the 20-foot wind tunnel during 1934. The experimental work included tests of the effect of the motion upon the rotor forces during the static-lift and forward-flight conditions at several rotor speeds and the determination of the relations between the forces generated by the rotor and the power required by it.

  2. Calibration Designs for Non-Monolithic Wind Tunnel Force Balances

    NASA Technical Reports Server (NTRS)

    Johnson, Thomas H.; Parker, Peter A.; Landman, Drew

    2010-01-01

    This research paper investigates current experimental designs and regression models for calibrating internal wind tunnel force balances of non-monolithic design. Such calibration methods are necessary for this class of balance because it has an electrical response that is dependent upon the sign of the applied forces and moments. This dependency gives rise to discontinuities in the response surfaces that are not easily modeled using traditional response surface methodologies. An analysis of current recommended calibration models is shown to lead to correlated response model terms. Alternative modeling methods are explored which feature orthogonal or near-orthogonal terms.

  3. User Interface Technology Transfer to NASA's Virtual Wind Tunnel System

    NASA Technical Reports Server (NTRS)

    vanDam, Andries

    1998-01-01

    Funded by NASA grants for four years, the Brown Computer Graphics Group has developed novel 3D user interfaces for desktop and immersive scientific visualization applications. This past grant period supported the design and development of a software library, the 3D Widget Library, which supports the construction and run-time management of 3D widgets. The 3D Widget Library is a mechanism for transferring user interface technology from the Brown Graphics Group to the Virtual Wind Tunnel system at NASA Ames as well as the public domain.

  4. Wind Tunnel Data Fusion and Immersive Visualization: A Case Study

    NASA Technical Reports Server (NTRS)

    Severance, Kurt; Brewster, Paul; Lazos, Barry; Keefe, Daniel

    2001-01-01

    This case study describes the process of fusing the data from several wind tunnel experiments into a single coherent visualization. Each experiment was conducted independently and was designed to explore different flow features around airplane landing gear. In the past, it would have been very difficult to correlate results from the different experiments. However, with a single 3-D visualization representing the fusion of the three experiments, significant insight into the composite flowfield was observed that would have been extremely difficult to obtain by studying its component parts. The results are even more compelling when viewed in an immersive environment.

  5. Stochastic Characterization of Flutter using Historical Wind Tunnel Data

    NASA Technical Reports Server (NTRS)

    Heeg, Jennifer

    2007-01-01

    Methods for predicting the onset of flutter during an experiment are traditionally applied treating the data as deterministic values. Uncertainty and variation in the data is often glossed over by using best-fit curves to represent the information. This paper applies stochastic treatments to wind tunnel data obtained for the Piezoelectric Aeroelastic Response Tailoring Investigation model. These methods include modal amplitude tracking, modal frequency tracking and several applications of the flutter margin method. The flutter margin method was developed by Zimmerman and Weissenburger, and extended by Poirel, Dunn and Porter to incorporate uncertainty. Much of the current work follows the future work recommendations of Poirel, Dunn and Porter.

  6. Incompressible viscous flow simulations of the NFAC wind tunnel

    NASA Technical Reports Server (NTRS)

    Champney, Joelle Milene

    1986-01-01

    The capabilities of an existing 3-D incompressible Navier-Stokes flow solver, INS3D, are extended and improved to solve turbulent flows through the incorporation of zero- and two-equation turbulence models. The two-equation model equations are solved in their high Reynolds number form and utilize wall functions in the treatment of solid wall boundary conditions. The implicit approximate factorization scheme is modified to improve the stability of the two-equation solver. Applications to the 3-D viscous flow inside the 80 by 120 feet open return wind tunnel of the National Full Scale Aerodynamics Complex (NFAC) are discussed and described.

  7. Evaluation of hydrogen as a cryogenic wind tunnel test gas

    NASA Technical Reports Server (NTRS)

    Haut, R. C.

    1977-01-01

    The nondimensional ratios used to describe various flow situations in hydrogen were determined and compared with the corresponding ideal diatomic gas ratios. The results were used to examine different inviscid flow configurations. The relatively high value of the characteristic rotational temperature causes the behavior of hydrogen, under cryogenic conditions, to deviate substantially from the behavior of an ideal diatomic gas in the compressible flow regime. Therefore, if an idea diatomic gas is to be modeled, cryogenic hydrogen is unacceptable as a wind tunnel test gas in a compressible flow situation.

  8. Acoustic Radiation from High-Speed Turbulent Boundary Layers in a Tunnel-Like Environment

    NASA Technical Reports Server (NTRS)

    Duan, Lian; Choudhari, Meelan M.; Zhang, Chao

    2015-01-01

    Direct numerical simulation of acoustic radiation from a turbulent boundary layer in a cylindrical domain will be conducted under the flow conditions corresponding to those at the nozzle exit of the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT) operated under noisy-flow conditions with a total pressure p(sub t) of 225 kPa and a total temperature of T(sub t) equal to 430 K. Simulations of acoustic radiation from a turbulent boundary layer over a flat surface are used as a reference configuration to illustrate the effects of the cylindrical enclosure. A detailed analysis of acoustic freestream disturbances in the cylindrical domain will be reported in the final paper along with a discussion pertaining to the significance of the flat-plate acoustic simulations and guidelines concerning the modeling of the effects of an axisymmetric tunnel wall on the noise field.

  9. Assessing the vegetation canopy influences on wind flow using wind tunnel experiments with artificial plants

    NASA Astrophysics Data System (ADS)

    Hong, Youngjoo; Kim, Dongyeob; Im, Sangjun

    2016-04-01

    Wind erosion causes serious problems and considerable threat in most regions of the world. Vegetation on the ground has an important role in controlling wind erosion by covering soil surface and absorbing wind momentum. A set of wind tunnel experiments was performed to quantitatively examine the effect of canopy structure on wind movement. Artificial plastic vegetations with different porosity and canopy shape were introduced as the model canopy. Normalized roughness length ( Z 0/ H) and shear velocity ratio ( R) were analyzed as a function of roughness density ( λ). Experiments showed that Z 0/ H increases and R decreases as λ reaches a maximum value, λ max, while the values of Z 0/ H and R showed little change with λ value beyond as λ max.

  10. Assessing the vegetation canopy influences on wind flow using wind tunnel experiments with artificial plants

    NASA Astrophysics Data System (ADS)

    Hong, Youngjoo; Kim, Dongyeob; Im, Sangjun

    2016-04-01

    Wind erosion causes serious problems and considerable threat in most regions of the world. Vegetation on the ground has an important role in controlling wind erosion by covering soil surface and absorbing wind momentum. A set of wind tunnel experiments was performed to quantitatively examine the effect of canopy structure on wind movement. Artificial plastic vegetations with different porosity and canopy shape were introduced as the model canopy. Normalized roughness length (Z 0/H) and shear velocity ratio (R) were analyzed as a function of roughness density (λ). Experiments showed that Z 0/H increases and R decreases as λ reaches a maximum value, λ max, while the values of Z 0/H and R showed little change with λ value beyond as λ max.

  11. Design and wind tunnel experimentation of a variable blade drag type vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Mays, Samuel; Bahr, Behnam

    2012-04-01

    The primary purpose of this research effort is to propose a novel efficiency boosting design feature in a drag type vertical axis wind turbine (VAWT), explore practicality through design and fabrication, and test the viability of the design through wind tunnel experiments. Using adaptive control surface design and an improved blade shape can be very useful in harnessing the wind's energy in low wind speed areas. The new design is based on a series of smaller blade elements to make any shape, which changes to reduce a negative resistance as it rotates and thus maximizing the useful torque. As such, these blades were designed into a modified Savonius wind turbine with the goal of improving upon the power coefficient produced by a more conventional design. The experiment yielded some positive observations with regard to starting characteristics. Torque and angular velocity data was recorded for both the conventional configuration and the newly built configuration and the torque and power coefficient results were compared.

  12. Data correlation and analysis of arc tunnel and wind tunnel tests of RSI joints and gaps. Volume 2: Data base

    NASA Technical Reports Server (NTRS)

    Christensen, H. E.; Kipp, H. W.

    1974-01-01

    Wind tunnel tests were conducted to determine the aerodynamic heating created by gaps in the reusable surface insulation (RSI) thermal protection system (TPS) for the space shuttle. The effects of various parameters of the RSI on convective heating characteristics are described. The wind tunnel tests provided a data base for accurate assessment of gap heating. Analysis and correlation of the data provide methods for predicting heating in the RSI gaps on the space shuttle.

  13. Wind Tunnel Tests of Parabolic Trough Solar Collectors: March 2001--August 2003

    SciTech Connect

    Hosoya, N.; Peterka, J. A.; Gee, R. C.; Kearney, D.

    2008-05-01

    Conducted extensive wind-tunnel tests on parabolic trough solar collectors to determine practical wind loads applicable to structural design for stress and deformation, and local component design for concentrator reflectors.

  14. Wind tunnel studies of gas dispersion from ground level source

    NASA Astrophysics Data System (ADS)

    Michálek, Petr; Zacho, David

    2015-05-01

    Measurements of gas dispersion from ground source were performed in a boundary layer wind tunnel in VZLU Prague. The measurements include non-buoyant gas dispersion behind a ground level source on a flat plane, on a simple rectangular building model and behind a model hill and rectangular barrier. These measurements will serve for verification of a new gas dispersion software being developed in VZLU. The dispersion model is intended for use by firemen and ambulance services in the case of an accident for immediate estimation of the area with dangerous gas concentration. The dispersion model will use precalculated results for chosen areas in the Czech Republic with industrial plants and residential building in the neighborhood. The size of contaminated area will be estimated using actual meteorological situation, i.e. wind speed and direction etc. and precalculated data of flow and dispersion in the chosen location.

  15. Enhanced focal-resolution of dipole sources using aeroacoustic time-reversal in a wind tunnel

    NASA Astrophysics Data System (ADS)

    Mimani, A.; Moreau, D. J.; Prime, Z.; Doolan, C. J.

    2016-05-01

    This paper presents the first application of the Point-Time-Reversal-Sponge-Layer (PTRSL) damping technique to enhance the focal-resolution of experimental flow-induced dipole sources obtained using the Time-Reversal (TR) source localization method. Experiments were conducted in an Anechoic Wind Tunnel for the case of a full-span cylinder located in a low Mach number cross-flow. The far-field acoustic pressure sampled using two line arrays of microphones located above and below the cylinder exhibited a dominant Aeolian tone. The aeroacoustic TR simulations were implemented using the time-reversed signals whereby the source map revealed the lift-dipole nature at the Aeolian tone frequency. A PTRSL (centred at the predicted dipole location) was shown to reduce the size of dipole focal spots to 7/20th of a wavelength as compared to one wavelength without its use, thereby dramatically enhancing the focal-resolution of the TR technique.

  16. Analytical and physical modeling program for the NASA Lewis Research Center's Altitude Wind Tunnel (AWT)

    NASA Technical Reports Server (NTRS)

    Abbott, J. M.; Deidrich, J. H.; Groeneweg, J. F.; Povinelli, L. A.; Reid, L.; Reinmann, J. J.; Szuch, J. R.

    1985-01-01

    An effort is currently underway at the NASA Lewis Research Center to rehabilitate and extend the capabilities of the Altitude Wind Tunnel (AWT). This extended capability will include a maximum test section Mach number of about 0.9 at an altitude of 55,000 ft and a -20 F stagnation temperature (octagonal test section, 20 ft across the flats). In addition, the AWT will include an icing and acoustic research capability. In order to insure a technically sound design, an AWT modeling program (both analytical and physical) was initiated to provide essential input to the AWT final design process. This paper describes the modeling program, including the rationale and criteria used in program definition, and presents some early program results.

  17. Wind Turbine Generator System Acoustic Noise Test Report for the ARE 442 Wind Turbine

    SciTech Connect

    Huskey, A.; van Dam, J.

    2010-11-01

    This test was conducted on the ARE 442 as part of the U.S. Department of Energy's (DOE's) Independent Testing project. This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. In total, five turbines are being tested at the National Wind Technology Center (NWTC) as a part of this project. Acoustic noise testing is one of up to five tests that may be performed on the turbines, including duration, safety and function, power performance, and power quality tests. The acoustic noise test was conducted to the IEC 61400-11 Edition 2.1.

  18. Aeroacoustic Characterization of the NASA Ames Experimental Aero-Physics Branch 32- by 48-Inch Subsonic Wind Tunnel with a 24-Element Phased Microphone Array

    NASA Technical Reports Server (NTRS)

    Costanza, Bryan T.; Horne, William C.; Schery, S. D.; Babb, Alex T.

    2011-01-01

    The Aero-Physics Branch at NASA Ames Research Center utilizes a 32- by 48-inch subsonic wind tunnel for aerodynamics research. The feasibility of acquiring acoustic measurements with a phased microphone array was recently explored. Acoustic characterization of the wind tunnel was carried out with a floor-mounted 24-element array and two ceiling-mounted speakers. The minimum speaker level for accurate level measurement was evaluated for various tunnel speeds up to a Mach number of 0.15 and streamwise speaker locations. A variety of post-processing procedures, including conventional beamforming and deconvolutional processing such as TIDY, were used. The speaker measurements, with and without flow, were used to compare actual versus simulated in-flow speaker calibrations. Data for wind-off speaker sound and wind-on tunnel background noise were found valuable for predicting sound levels for which the speakers were detectable when the wind was on. Speaker sources were detectable 2 - 10 dB below the peak background noise level with conventional data processing. The effectiveness of background noise cross-spectral matrix subtraction was assessed and found to improve the detectability of test sound sources by approximately 10 dB over a wide frequency range.

  19. Results of an investigation of the acoustic and vibrational environment of a full scale space shuttle orbiter structural test panel with simulated TPS in the Ames unitary plan wind tunnel, model 81-0, test OS8A and B

    NASA Technical Reports Server (NTRS)

    Kingsland, R. B.

    1977-01-01

    Results of tests OS8A and B and pertinent test and model information are presented. The test was conducted in two parts. Test OS8A was performed in the NASA/ARC unitary 11-foot section and OS8B was conducted in the NASA/ARC unitary 9 x 7 tunnel. Test objectives were to investigate thermal protection system (TPS) tile sensitivity to extreme pressure gradients and vibration and to define the TPS aerodynamic environment. The model utilized for OS8 was a full-scale representation of a portion of the space shuttle orbiter lower wing carry-through structure forward of the aft tank strut and propellant lines. Thermal protection tiles were simulated on the model. The model was instrumented with static pressure orifices, accelerometers, and dynamic pressure transducers (Kulites). A total rake was utilized to obtain boundary layer surveys.

  20. Engineering and fabrication cost considerations for cryogenic wind tunnel models

    NASA Technical Reports Server (NTRS)

    Boykin, R. M., Jr.; Davenport, J. B., Jr.

    1983-01-01

    Design and fabrication cost drivers for cryogenic transonic wind tunnel models are defined. The major cost factors for wind tunnel models are model complexity, tolerances, surface finishes, materials, material validation, and model inspection. The cryogenic temperatures require the use of materials with relatively high fracture toughness but at the same time high strength. Some of these materials are very difficult to machine, requiring extensive machine hours which can add significantly to the manufacturing costs. Some additional engineering costs are incurred to certify the materials through mechanical tests and nondestructive evaluation techniques, which are not normally required with conventional models. When instrumentation such as accelerometers and electronically scanned pressure modules is required, temperature control of these devices needs to be incorporated into the design, which requires added effort. Additional thermal analyses and subsystem tests may be necessary, which also adds to the design costs. The largest driver to the design costs is potentially the additional static and dynamic analyses required to insure structural integrity of the model and support system.

  1. Effect of Turbulence in Wind-Tunnel Measurements

    NASA Technical Reports Server (NTRS)

    Dryden, H L; Kuethe, A M

    1931-01-01

    This paper gives some quantitative measurements of wind tunnel turbulence and its effect on the air resistance of spheres and airship models, measurements made possible by the hot wire anemometer and associated apparatus in its original form was described in Technical Report no. 320 and some modifications are presented in an appendix to the present paper. One important result of the investigation is a curve by means of which measurements of the air resistance of spheres can be interpreted to give the turbulence quantitatively. Another is the definite proof that the discrepancies in the results on the N. P. L. Standard airship models are due mainly to differences in the turbulences of the wind tunnels in which the tests were made. An attempt is made to interpret the observed results in terms of the boundary layer theory and for this purpose a brief account is given of the physical bases of this theory and of conceptions that have been obtained by analogy with the laws of flow in pipes.

  2. Testing a Parachute for Mars in World's Largest Wind Tunnel

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The team developing the landing system for NASA's Mars Science Laboratory tested the deployment of an early parachute design in mid-October 2007 inside the world's largest wind tunnel, at NASA Ames Research Center, Moffett Field, California.

    In this image, two engineers are dwarfed by the parachute, which holds more air than a 280-square-meter (3,000-square-foot) house and is designed to survive loads in excess of 36,000 kilograms (80,000 pounds).

    The parachute, built by Pioneer Aerospace, South Windsor, Connecticut, has 80 suspension lines, measures more than 50 meters (165 feet) in length, and opens to a diameter of nearly 17 meters (55 feet). It is the largest disk-gap-band parachute ever built and is shown here inflated in the test section with only about 3.8 meters (12.5 feet) of clearance to both the floor and ceiling.

    The wind tunnel, which is 24 meters (80 feet) tall and 37 meters (120 feet) wide and big enough to house a Boeing 737, is part of the National Full-Scale Aerodynamics Complex, operated by the U.S. Air Force, Arnold Engineering Development Center.

    NASA's Jet Propulsion Laboratory, Pasadena, California, is building and testing the Mars Science Laboratory spacecraft for launch in 2009. The mission will land a roving analytical laboratory on the surface of Mars in 2010. JPL is a division of the California Institute of Technology.

  3. Further buffeting tests in a cryogenic wind tunnel

    NASA Technical Reports Server (NTRS)

    Mabey, D. G.; Boyden, R. P.; Johnson, W. G., Jr.

    1992-01-01

    Further measurements of buffeting, using wing-root strain gauges, were made in the NASA Langley 0.3 m Cryogenic Wind Tunnel to refine techniques which will be used in larger cryogenic facilities such as the United States National Transonic Facility (NTF) and European Transonic Wind Tunnel (ETW). The questions addressed included the relative importance of variations in frequency parameter and Reynolds number, the choice of model material (considering both stiffness and damping) and the effects of static aeroelastic distortion. The main series of tests was made on half models of slender 65 deg delta wings with a sharp leading edge. The three delta wings had the same planform but widely different bending stiffness and frequencies (obtained by varying both the material and the thickness of the wings). It was known that the flow on this configuration would be insensitive to variations in Reynold number. Additional tests were made on one unswept half-wing of aspect ratio 1.5 with an NPL 9510 aerofoil section, known to be sensitive to variations in Reynolds number at transonic speeds. For brevity the test Mach numbers were restricted to M = 0.21 and 0.35 for the delta wings and to M = 0.30 for the unswept wing.

  4. Simulation Method for Wind Tunnel Based Virtual Flight Testing

    NASA Astrophysics Data System (ADS)

    Li, Hao; Zhao, Zhong-Liang; Fan, Zhao-Lin

    The Wind Tunnel Based Virtual Flight Testing (WTBVFT) could replicate the actual free flight and explore the aerodynamics/flight dynamics nonlinear coupling mechanism during the maneuver in the wind tunnel. The basic WTBVFT concept is to mount the test model on a specialized support system which allows for the model freely rotational motion, and the aerodynamic loading and motion parameters are measured simultaneously during the model motion. The simulations of the 3-DOF pitching motion of a typical missile in the vertical plane are performed with the openloop and closed-loop control methods. The objective is to analyze the effect of the main differences between the WTBVFT and the actual free flight, and study the simulation method for the WTBVFT. Preliminary simulation analyses have been conducted with positive results. These results indicate that the WTBVFT that uses closed-loop autopilot control method with the pitch angular rate feedback signal is able to replicate the actual free flight behavior within acceptable differences.

  5. Propulsion simulator for magnetically-suspended wind tunnel models

    NASA Technical Reports Server (NTRS)

    Joshi, P. B.; Malonson, M. R.; Sacco, G. P.; Goldey, C. L.; Garbutt, Keith; Goodyer, M.

    1992-01-01

    In order to demonstrate the measurement of aerodynamic forces/moments, including the effects of exhaust jets in Magnetic Suspension and Balance System (MSBS) wind tunnels, two propulsion simulator models were developed at Physical Sciences Inc. (PSI). Both the small-scale model (1 in. diameter X 8 in. long) and the large-scale model (2.5 in. diameter X 15 in. long) employed compressed, liquefied carbon dioxide as a propellant. The small-scale simulator, made from a highly magnetizable iron alloy, was demonstrated in the 7 in. MSBS wind tunnel at the University of Southampton. It developed a maximum thrust of approximate 1.3 lbf with a 0.098 in. diameter nozzle and 0.7 lbf with a 0.295 in. diameter nozzle. The Southampton MSBS was able to control the simulator at angles-of attack up to 20 deg. The large-scale simulator was demonstrated to operate in both a steady-state and a pulse mode via a miniaturized solinoid valve. It developed a stable and repeatable thrust of 2.75 lbf over a period of 4s and a nozzle pressure ratio (NPR) of 5.

  6. Large-scale V/STOL testing. [in wind tunnels

    NASA Technical Reports Server (NTRS)

    Koenig, D. G.; Aiken, T. N.; Aoyagi, K.; Falarski, M. D.

    1977-01-01

    Several facets of large-scale testing of V/STOL aircraft configurations are discussed with particular emphasis on test experience in the Ames 40- by 80-foot wind tunnel. Examples of powered-lift test programs are presented in order to illustrate tradeoffs confronting the planner of V/STOL test programs. It is indicated that large-scale V/STOL wind-tunnel testing can sometimes compete with small-scale testing in the effort required (overall test time) and program costs because of the possibility of conducting a number of different tests with a single large-scale model where several small-scale models would be required. The benefits of both high- and full-scale Reynolds numbers, more detailed configuration simulation, and number and type of onboard measurements increase rapidly with scale. Planning must be more detailed at large scale in order to balance the trade-offs between the increased costs, as number of measurements and model configuration variables increase and the benefits of larger amounts of information coming out of one test.

  7. Wind tunnel test IA300 analysis and results, volume 1

    NASA Technical Reports Server (NTRS)

    Kelley, P. B.; Beaufait, W. B.; Kitchens, L. L.; Pace, J. P.

    1987-01-01

    The analysis and interpretation of wind tunnel pressure data from the Space Shuttle wind tunnel test IA300 are presented. The primary objective of the test was to determine the effects of the Space Shuttle Main Engine (SSME) and the Solid Rocket Booster (SRB) plumes on the integrated vehicle forebody pressure distributions, the elevon hinge moments, and wing loads. The results of this test will be combined with flight test results to form a new data base to be employed in the IVBC-3 airloads analysis. A secondary objective was to obtain solid plume data for correlation with the results of gaseous plume tests. Data from the power level portion was used in conjunction with flight base pressures to evaluate nominal power levels to be used during the investigation of changes in model attitude, eleveon deflection, and nozzle gimbal angle. The plume induced aerodynamic loads were developed for the Space Shuttle bases and forebody areas. A computer code was developed to integrate the pressure data. Using simplified geometrical models of the Space Shuttle elements and components, the pressure data were integrated to develop plume induced force and moments coefficients that can be combined with a power-off data base to develop a power-on data base.

  8. Wind Tunnel Testing for the Stratospheric Observatory for Infrared Astronomy

    NASA Technical Reports Server (NTRS)

    Schenberger, Deborah; Alvarez, Teresa (Technical Monitor)

    1994-01-01

    NASA Ames Research Center is pursuing the development of SOFIA, the Stratospheric Observatory For Infrared Astronomy. SOFIA will consist of a 2.5 meter telescope mounted aft of the wing of a Boeing 747 aircraft. Since a large portion of the infrared spectrum is not visible at ground level due to absorption by water vapor in the atmosphere below 40,000 feet, it is highly desirable to make observations above this altitude. SOFIA will provide the opportunity for astronomers to conduct high-altitude research for extended periods of time. Current study is focused on wind tunnel testing for the open cavity. If not controlled, air would create resonance and damage the telescope. For this reason, SOFIA will design a boundary layer control device to achieve laminar flow over the cavity. This also provides a clearer flow for seeing, thus improving resolution on infrared sources. Other effects being tested in the wind tunnel are aerodynamic torque loads on the telescope, and flutter loads on the tail.

  9. An introduction to testing parachutes in wind tunnels

    SciTech Connect

    Macha, J.

    1991-01-01

    This paper reviews some of the technical considerations and current practices for testing parachutes in conventional wind tunnels. Special challenges to the experimentalist caused by the fabric construction, flexible geometry, and buff shape of parachutes are discussed. In particular, the topics of measurement technique, similarity considerations, and wall interference are addressed in a summary manner. Many references are cited which provide detailed coverage of the state of the art in testing methods. From the discussions presented, it is obvious that there are some serious problems with state of the art methods, especially in the area of canopy instrumentation and when working with reduced-scale models. But if the experimentalist is informed about the relative importance of the various factors for a specific test objective, it is usually possible to design a test that will yield meaningful results. The lower cost and the more favorable measurement environment of wind tunnels make their use an attractive alternative to flight testing whenever possible. 26 refs., 5 figs., 1 tab.

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

    NASA Technical Reports Server (NTRS)

    Breunlin, D. C.; Sargent, N. B.

    1972-01-01

    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.

  11. Noise measurements from an ejector suppressor nozzle in the NASA Lewis 9- by 15-foot low speed wind tunnel

    NASA Technical Reports Server (NTRS)

    Krejsa, Eugene A.; Cooper, Beth A.; Hall, David G.; Khavaran, Abbas

    1990-01-01

    Acoustic results are presented of a cooperative nozzle test program between NASA and Pratt and Whitney, conducted in the NASA-Lewis 9 x 15 ft Anechoic Wind Tunnel. The nozzle tested was the P and W Hypermix Nozzle concept, a 2-D lobed mixer nozzle followed by a short ejector section made to promote rapid mixing of the induced ejector nozzle flow. Acoustic and aerodynamic measurements were made to determine the amount of ejector pumping, degree of mixing, and noise reduction achieved. A series of tests were run to verify the acoustic quality of this tunnel. The results indicated that the tunnel test section is reasonably anechoic but that background noise can limit the amount of suppression observed from suppressor nozzles. Also, a possible internal noise was observed in the air supply system. The P and W ejector suppressor nozzle demonstrated the potential of this concept to significantly reduce jet noise. Significant reduction in low frequency noise was achieved by increasing the peak jet noise frequency. This was accomplished by breaking the jet into segments with smaller dimensions than those of the baseline nozzle. Variations in ejector parameters had little effect on the noise for the geometries and the range of temperatures and pressure ratios tested.

  12. Build a Wind Tunnel that Won't Blow Your Budget

    ERIC Educational Resources Information Center

    Fitzgerald, Mike

    2005-01-01

    In this article, the author gives basic information on constructing a wind tunnel that teachers can use for instructional activities with their students for many years to come. He illustrates and describes the procedure and materials that he developed in constructing his own wind tunnel. This information should be viewed as a guide. (Contains 1…

  13. Development of a process control computer device for the adaptation of flexible wind tunnel walls

    NASA Technical Reports Server (NTRS)

    Barg, J.

    1982-01-01

    In wind tunnel tests, the problems arise of determining the wall pressure distribution, calculating the wall contour, and controlling adjustment of the walls. This report shows how these problems have been solved for the high speed wind tunnel of the Technical University of Berlin.

  14. A numerical study of the effects of wind tunnel wall proximity on an airfoil model

    NASA Technical Reports Server (NTRS)

    Potsdam, Mark; Roberts, Leonard

    1990-01-01

    A procedure was developed for modeling wind tunnel flows using computational fluid dynamics. Using this method, a numerical study was undertaken to explore the effects of solid wind tunnel wall proximity and Reynolds number on a two-dimensional airfoil model at low speed. Wind tunnel walls are located at varying wind tunnel height to airfoil chord ratios and the results are compared with freestream flow in the absence of wind tunnel walls. Discrepancies between the constrained and unconstrained flows can be attributed to the presence of the walls. Results are for a Mach Number of 0.25 at angles of attack through stall. A typical wind tunnel Reynolds number of 1,200,000 and full-scale flight Reynolds number of 6,000,000 were investigated. At this low Mach number, wind tunnel wall corrections to Mach number and angle of attack are supported. Reynolds number effects are seen to be a consideration in wind tunnel testing and wall interference correction methods. An unstructured grid Navier-Stokes code is used with a Baldwin-Lomax turbulence model. The numerical method is described since unstructured flow solvers present several difficulties and fundamental differences from structured grid codes, especially in the area of turbulence modeling and grid generation.

  15. Self streamlining wind tunnel: Low speed testing and transonic test section design

    NASA Technical Reports Server (NTRS)

    Wolf, S. W. D.; Goodyer, M. J.

    1977-01-01

    Comprehensive aerodynamic data on an airfoil section were obtained through a wide range of angles of attack, both stalled and unstalled. Data were gathered using a self streamlining wind tunnel and were compared to results obtained on the same section in a conventional wind tunnel. The reduction of wall interference through streamline was demonstrated.

  16. Effect of wind tunnel air velocity on VOC flux rates from CAFO manure and wastewater

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind tunnels and flux chambers are often used to estimate volatile organic compound (VOC) emissions from animal feeding operations (AFOs) without regard to air velocity or sweep air flow rates. Laboratory experiments were conducted to evaluate the effect of wind tunnel air velocity on VOC emission ...

  17. Flow-Visualization Techniques Used at High Speed by Configuration Aerodynamics Wind-Tunnel-Test Team

    NASA Technical Reports Server (NTRS)

    Lamar, John E. (Editor)

    2001-01-01

    This paper summarizes a variety of optically based flow-visualization techniques used for high-speed research by the Configuration Aerodynamics Wind-Tunnel Test Team of the High-Speed Research Program during its tenure. The work of other national experts is included for completeness. Details of each technique with applications and status in various national wind tunnels are given.

  18. Static Aeroelastic Scaling and Analysis of a Sub-Scale Flexible Wing Wind Tunnel Model

    NASA Technical Reports Server (NTRS)

    Ting, Eric; Lebofsky, Sonia; Nguyen, Nhan; Trinh, Khanh

    2014-01-01

    This paper presents an approach to the development of a scaled wind tunnel model for static aeroelastic similarity with a full-scale wing model. The full-scale aircraft model is based on the NASA Generic Transport Model (GTM) with flexible wing structures referred to as the Elastically Shaped Aircraft Concept (ESAC). The baseline stiffness of the ESAC wing represents a conventionally stiff wing model. Static aeroelastic scaling is conducted on the stiff wing configuration to develop the wind tunnel model, but additional tailoring is also conducted such that the wind tunnel model achieves a 10% wing tip deflection at the wind tunnel test condition. An aeroelastic scaling procedure and analysis is conducted, and a sub-scale flexible wind tunnel model based on the full-scale's undeformed jig-shape is developed. Optimization of the flexible wind tunnel model's undeflected twist along the span, or pre-twist or wash-out, is then conducted for the design test condition. The resulting wind tunnel model is an aeroelastic model designed for the wind tunnel test condition.

  19. Application of Oil Film Interferometry Skin-Friction to Large Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Driver, David M.

    1998-01-01

    The oil film interferometry skin-friction technique is described and applied to flows in some of the NASA Ames large wind tunnel facilities. Various schemes for applying the technique are discussed. Results are shown for tests in several wind tunnels which illustrate the oil film's ability to measure a variety of flow features such as shock waves separation, and 3D flow.

  20. NEW VERSATILE AEROSOL GENERATION SYSTEM DEVELOPED FOR USE IN A LARGE WIND TUNNEL

    EPA Science Inventory

    A new aerosol generation system was developed to accommodate a variety of research activities performed within a large wind tunnel. Because many of the velocity measurements are taken in the wind tunnel with a laser Doppler anemometer (LDA), it is necessary to maintain an aero...

  1. Vegetative buffers for swine odor mitigation - wind tunnel evaluation of air flow dynamics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Scale model wind tunnel experiments were completed to determine the effectiveness and feasibility of vegetative buffers to mitigate swine odor and particulate transport. Three series of wind tunnel experiments were completed. The first included four swine housing unit models and either a slurry tank...

  2. Application of Neural Networks to Wind tunnel Data Response Surface Methods

    NASA Technical Reports Server (NTRS)

    Lo, Ching F.; Zhao, J. L.; DeLoach, Richard

    2000-01-01

    The integration of nonlinear neural network methods with conventional linear regression techniques is demonstrated for representative wind tunnel force balance data modeling. This work was motivated by a desire to formulate precision intervals for response surfaces produced by neural networks. Applications are demonstrated for representative wind tunnel data acquired at NASA Langley Research Center and the Arnold Engineering Development Center in Tullahoma, TN.

  3. 6. CLOSEUP VIEW OF TENFOOT WIND TUNNEL (1991). WrightPatterson ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. CLOSE-UP VIEW OF TEN-FOOT WIND TUNNEL (1991). - Wright-Patterson Air Force Base, Area B, Buildings 25 & 24,10-foot & 20-foot Wind Tunnel Complex, Northeast side of block bounded by K, G, Third, & Fifth Streets, Dayton, Montgomery County, OH

  4. 10. INTERIOR VIEW OF WIND TUNNEL (1991). WrightPatterson Air ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. INTERIOR VIEW OF WIND TUNNEL (1991). - Wright-Patterson Air Force Base, Area B, Buildings 25 & 24,10-foot & 20-foot Wind Tunnel Complex, Northeast side of block bounded by K, G, Third, & Fifth Streets, Dayton, Montgomery County, OH

  5. 11. INTERIOR VIEW OF WIND TUNNEL (1991). WrightPatterson Air ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. INTERIOR VIEW OF WIND TUNNEL (1991). - Wright-Patterson Air Force Base, Area B, Buildings 25 & 24,10-foot & 20-foot Wind Tunnel Complex, Northeast side of block bounded by K, G, Third, & Fifth Streets, Dayton, Montgomery County, OH

  6. 3. VIEW OF WIND TUNNEL, LOOKING NORTHWEST (1991). WrightPatterson ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW OF WIND TUNNEL, LOOKING NORTHWEST (1991). - Wright-Patterson Air Force Base, Area B, Buildings 25 & 24,10-foot & 20-foot Wind Tunnel Complex, Northeast side of block bounded by K, G, Third, & Fifth Streets, Dayton, Montgomery County, OH

  7. 9. INTERIOR VIEW OF WIND TUNNEL (1991). WrightPatterson Air ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. INTERIOR VIEW OF WIND TUNNEL (1991). - Wright-Patterson Air Force Base, Area B, Buildings 25 & 24,10-foot & 20-foot Wind Tunnel Complex, Northeast side of block bounded by K, G, Third, & Fifth Streets, Dayton, Montgomery County, OH

  8. Effects of screens set characteristics on the flow field in a wind tunnel

    NASA Astrophysics Data System (ADS)

    Santos, A. M.; Souza, D. B.; Costa, F. O.; Farias, M. H.; Massari, P. de L.; Araújo, S.; Zanirath, Y. B.

    2016-07-01

    Wind tunnels have broad range of applications, and although there are common elements among the different types of tunnels, the layout and configuration of each facility will depend on its particular purpose. The flow conditioners section is a common component for all tunnels, and frequently contains flow straighteners and screens [1]. The role of screens is to minimize non uniformities or turbulence level on the flow field. In this work, the development and characteristics of the vertical velocity profile along an atmospheric wind tunnel length were evaluated. By using such data as initial reference, the effects, on the flow, when screens set is inserted on it were analyzed, in order to identify which changes could be done in the wind tunnel configuration to improve the characteristics of the flow field. Such atmospheric wind tunnel is a facility which belongs to the Brazilian National Metrology Institute INMETRO.

  9. Wind-tunnel investigation of aerodynamic performance, steady amd vibratory loads, surface temperatures, and acoustic characteristics of a large-scale twin-engine upper-surface blown jet-flap configuration

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Static and wind-on tests were conducted to determine the aerodynamic characteristics of and the effects of jet impingement on the wing of a large scale upper surface blown configuration powered with an actual turbine engine. The wing and flaps were instrumented with experimental dual-sensing transducer units consisting of a fluctuating pressure gage, a vibratory accelerometer, and a surface mounted alumel thermocouple. Noise directivity and spectral content measurements were obtained for various flap configurations and various engine thrust settings to provide baseline noise data for other upper surface blown configurations.

  10. A wind-tunnel investigation of wind-turbine wakes in different yawed and loading conditions

    NASA Astrophysics Data System (ADS)

    Bastankhah, Majid; Porté-Agel, Fernando

    2015-04-01

    Wind-turbine wakes have negative effects on wind-farm performance. They are associated with: (a) the velocity deficit, which reduces the generated power of downwind turbines; and (b) the turbulence level, which increases the fatigue loads on downwind turbines. Controlling the yaw angle of turbines can potentially improve the performance of wind farms by deflecting the wake away from downwind turbines. However, except for few studies, wakes of yawed turbines still suffer from the lack of systematic research. To fill this research gap, we performed wind-tunnel experiments in the recirculating boundary-layer wind tunnel at the WIRE Laboratory of EPFL to better understand the wakes of yawed turbines. High-resolution stereoscopic particle image-velocimetry (S-PIV) was used to measure three velocity components in a horizontal plane located downwind of a horizontal-axis, three-blade model turbine. A servo-controller was connected to the DC generator of the turbine, which allowed us to apply different loadings. The power and thrust coefficients of the turbine were also measured for each case. These power and thrust measurements together with the highly-resolved flow measurements enabled us to study different wake characteristics such as the energy entrainment from the outer flow into the wake, the wake deflection and the helicoidal tip vortices for yawed turbines.

  11. Subterahertz acoustical pumping of electronic charge in a resonant tunneling device.

    PubMed

    Young, E S K; Akimov, A V; Henini, M; Eaves, L; Kent, A J

    2012-06-01

    We demonstrate that controlled subnanosecond bursts of electronic charge can be transferred through a resonant tunneling diode by successive picosecond acoustic pulses. The effect exploits the nonlinear current-voltage characteristics of the device and its asymmetric response to the compressive and tensile components of the strain pulse. This acoustoelectronic pump opens new possibilities for the control of quantum phenomena in nanostructures. PMID:23003634

  12. Characteristics of natural wind simulations in the TUM boundary layer wind tunnel

    NASA Astrophysics Data System (ADS)

    Kozmar, Hrvoje

    2011-11-01

    The boundary layer wind tunnel at the Technische Universität München was tested for atmospheric boundary layer (ABL) simulations. The ABLs developing above rural, suburban, and urban terrains were reproduced using the Counihan method, i.e., castellated barrier wall, vortex generators, and a fetch of surface roughness elements. A series of flow-characteristic evaluations was performed to investigate the flow development and uniformity. Experimental results presented as mean velocity, turbulence intensity, integral length scale of turbulence, Reynolds stress, and power spectral density of velocity fluctuations were compared with the ESDU data and/or theoretical models. Generated ABL wind-tunnel simulations compare well with the rural, suburban, and urban ABLs. In the test section area used for experiments on structural models, the ABL simulation is developed and uniform. Results of this study indicate the boundary layer wind tunnel at the Technische Universität München can be successfully employed in a broad spectrum of engineering, environmental, and micrometeorological studies, where it is required to accurately reproduce ABL characteristics.

  13. Turbofan Noise Studied in Unique Model Research Program in NASA Glenn's 9- by 15-Foot Low-Speed Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Hughes, Christopher E.

    2001-01-01

    A comprehensive aeroacoustic research program called the Source Diagnostic Test was recently concluded in NASA Glenn Research Center's 9- by 15-Foot Low Speed Wind Tunnel. The testing involved representatives from Glenn, NASA Langley Research Center, GE Aircraft Engines, and the Boeing Company. The technical objectives of this research were to identify the different source mechanisms of noise in a modern, high-bypass turbofan aircraft engine through scale-model testing and to make detailed acoustic and aerodynamic measurements to more fully understand the physics of how turbofan noise is generated.

  14. CFD and experimental data of closed-loop wind tunnel flow

    PubMed Central

    Calautit, John Kaiser; Hughes, Ben Richard

    2016-01-01

    The data presented in this article were the basis for the study reported in the research articles entitled ‘A validated design methodology for a closed loop subsonic wind tunnel’ (Calautit et al., 2014) [1], which presented a systematic investigation into the design, simulation and analysis of flow parameters in a wind tunnel using Computational Fluid Dynamics (CFD). The authors evaluated the accuracy of replicating the flow characteristics for which the wind tunnel was designed using numerical simulation. Here, we detail the numerical and experimental set-up for the analysis of the closed-loop subsonic wind tunnel with an empty test section. PMID:26958641

  15. Linear and Nonlinear Analyses of a Wind-Tunnel Balance

    NASA Technical Reports Server (NTRS)

    Karkehabadi, R.; Rhew, R. D.

    2004-01-01

    The NASA Langley Research Center (LaRC) has been designing strain-gauge balances for utilization in wind tunnels since its inception. The utilization of balances span a wide variety of aerodynamic tests. A force balance is an inherently critically stressed component due to the requirements of measurement sensitivity. Force balance stress analysis and acceptance criteria are under review due to LaRC wind tunnel operational safety requirements. This paper presents some of the analyses done at NASA LaRC. Research and analyses were performed in order to investigate the structural integrity of the balances and better understand their performance. The analyses presented in this paper are helpful in understanding the overall behavior of an existing balance and can also be used in design of new balances to enhance their performance. As a first step, maximum load combination is used for linear structural analysis. When nonlinear effects are encountered, the analysis is extended to include the nonlinearities. Balance 1621 is typical for LaRC designed balances and was chosen for this study due to its traditional high load capacity, Figure 1. Maximum loading occurs when all 6 components are applied simultaneously with their maximum value allowed (limit load). This circumstance normally will not occur in the wind tunnel. However, if it occurs, is the balance capable of handling the loads with an acceptable factor of safety? Preliminary analysis using Pro/Mechanica indicated that this balance might experience nonlinearity. It was decided to analyze this balance by using NASTRAN so that a nonlinear analysis could be conducted. Balance 1621 was modeled and meshed in PATRAN for analysis in NASTRAN. The model from PATRAN/NASTRAN is compared to the one from Pro/Mechanica. For a complete analysis, it is necessary to consider all the load cases as well as use a dense mesh near all the edges. Because of computer limitations, it is not feasible to analyze model with the dense mesh near

  16. Wind Tunnel Investigation of Ground Wind Loads for Ares Launch Vehicle

    NASA Technical Reports Server (NTRS)

    Keller, Donald F.; Ivanco, Thomas G.

    2010-01-01

    A three year program was conducted at the NASA Langley Research Center (LaRC) Aeroelasticity Branch (AB) and Transonic Dynamics Tunnel (TDT) with the primary objective to acquire scaled steady and dynamic ground-wind loads (GWL) wind-tunnel data for rollout, on-pad stay, and on-pad launch configurations for the Ares I-X Flight Test Vehicle (FTV). The experimental effort was conducted to obtain an understanding of the coupling of aerodynamic and structural characteristics that can result in large sustained wind-induced oscillations (WIO) on such a tall and slender launch vehicle and to generate a unique database for development and evaluation of analytical methods for predicting steady and dynamic GWL, especially those caused by vortex shedding, and resulting in significant WIO. This paper summarizes the wind-tunnel test program that employed two dynamically-aeroelastically scaled GWL models based on the Ares I-X Flight Test Vehicle. The first model tested, the GWL Checkout Model (CM), was a relatively simple model with a secondary objective of restoration and development of processes and methods for design, fabrication, testing, and data analysis of a representative ground wind loads model. In addition, parametric variations in surface roughness, Reynolds number, and protuberances (on/off) were investigated to determine effects on GWL characteristics. The second windtunnel model, the Ares I-X GWL Model, was significantly more complex and representative of the Ares I-X FTV and included the addition of simplified rigid geometrically-scaled models of the Kennedy Space Center (KSC) Mobile Launch Platform (MLP) and Launch Complex 39B primary structures. Steady and dynamic base bending moment as well as model response and steady and unsteady pressure data was acquired during the testing of both models. During wind-tunnel testing of each model, flow conditions (speed and azimuth) where significant WIO occurred, were identified and thoroughly investigated. Scaled data from

  17. Ion acoustic waves and related plasma observations in the solar wind

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Marsch, E.; Pilipp, W.; Schwenn, R.; Rosenbauer, H.

    1979-01-01

    The paper presents a study of the relationship between the interplanetary ion acoustic waves detected by Helios and the macroscopic and microscopic characteristics of the solar wind plasma. Two major mechanisms, an electron heat flux instability and a double-ion beam instability, are considered for generating the ion-acoustic-like waves observed in the solar wind. The results provide support to both mechanisms for generating the solar wind ion acoustic waves, although each mechanism has problems under certain conditions.

  18. The application of cryogenics to high Reynolds number testing in wind tunnels. II - Development and application of the cryogenic wind tunnel concept

    NASA Technical Reports Server (NTRS)

    Kilgore, R. A.; Dress, D. A.

    1984-01-01

    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.

  19. Wind-Turbine Wakes in a Convective Boundary Layer: A Wind-Tunnel Study

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Markfort, Corey D.; Porté-Agel, Fernando

    2013-02-01

    Thermal stability changes the properties of the turbulent atmospheric boundary layer, and in turn affects the behaviour of wind-turbine wakes. To better understand the effects of thermal stability on the wind-turbine wake structure, wind-tunnel experiments were carried out with a simulated convective boundary layer (CBL) and a neutral boundary layer. The CBL was generated by cooling the airflow to 12-15 °C and heating up the test section floor to 73-75 °C. The freestream wind speed was set at about 2.5 m s-1, resulting in a bulk Richardson number of -0.13. The wake of a horizontal-axis 3-blade wind-turbine model, whose height was within the lowest one third of the boundary layer, was studied using stereoscopic particle image velocimetry (S-PIV) and triple-wire (x-wire/cold-wire) anemometry. Data acquired with the S-PIV were analyzed to characterize the highly three-dimensional turbulent flow in the near wake (0.2-3.2 rotor diameters) as well as to visualize the shedding of tip vortices. Profiles of the mean flow, turbulence intensity, and turbulent momentum and heat fluxes were measured with the triple-wire anemometer at downwind locations from 2-20 rotor diameters in the centre plane of the wake. In comparison with the wake of the same wind turbine in a neutral boundary layer, a smaller velocity deficit (about 15 % at the wake centre) is observed in the CBL, where an enhanced radial momentum transport leads to a more rapid momentum recovery, particularly in the lower part of the wake. The velocity deficit at the wake centre decays following a power law regardless of the thermal stability. While the peak turbulence intensity (and the maximum added turbulence) occurs at the top-tip height at a downwind distance of about three rotor diameters in both cases, the magnitude is about 20 % higher in the CBL than in the neutral boundary layer. Correspondingly, the turbulent heat flux is also enhanced by approximately 25 % in the lower part of the wake, compared to that

  20. Building 865 Hypersonic Wind Tunnel Power System Analysis

    SciTech Connect

    Schneider, Larry X.

    2015-02-01

    This report documents the characterization and analysis of a high current power supply for the building 865 Hypersonic Wind Tunnel at Sandia National Laboratories. The system described in this report became operational in 2013, replacing the original 1968 system which employed an induction voltage regulator. This analysis and testing was completed to help the parent organization understand why an updated and redesigned power system was not delivering adequate power to resistive heater elements in the HWT. This analysis led to an improved understanding of the design and operation of the revised 2013 power supply system and identifies several reasons the revised system failed to achieve the performance of the original power supply installation. Design modifications to improve the performance of this system are discussed.

  1. Wind tunnel experiments on two blunt cones at Ma6

    NASA Astrophysics Data System (ADS)

    Zhang, Yunchi; Li, Cunbiao; State Key LaboratoryTurbulence; Complex Systems Team

    2015-11-01

    Wind tunnel experiments are performed on two 5° half-angle blunt cones over Mach 6 flow for 0° and 10° angle of attack. The temperature distributions on both windward and leeward sides are obtained by temperature sensitive painting (TSP) technique and the fluctuation pressure is measured by PCB pressure sensors for 7 meridian lines between the central meridian lines of the windward and the leeward by 30° step. Boundary layer transition is implied by the temperature distribution and power spectral evolution of the fluctuation pressure. It is found there exists a streamwise high-temperature strip near the central meridian line of the leeward side and transition is most likely to occur along the strip (earlier than the windward side and 0° angle of attack). Besides, the radius of the cone tip has an effective influence on the transition location. Transition is more likely to occur on the cone with the sharper tip.

  2. Low Speed PSP Testing in Production Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Bell, James; Mehta, Rabi; Schairer, Ed; Hand, Larry; Nixon, David (Technical Monitor)

    1998-01-01

    The brightness signal from a pressure-sensitive paint varies inversely with absolute pressure. Consequently high signal-to-noise ratios are required to resolve aerodynamic pressure fields at low speeds, where the pressure variation around an object might only be a few percent of the mean pressure. This requirement is unavoidable, and implies that care must be taken to minimize noise sources present in the measurement. This paper discusses and compares the main noise sources in low speed PSP testing using the "classical" intensity-based single-luminophore technique. These are: temperature variation, model deformation, and lamp drift/paint degradation. Minimization of these error sources from the point of view of operation in production wind tunnels is discussed, with some examples from recent tests in NASA Ames facilities.

  3. Hypersonic Wind Tunnel Calibration Using the Modern Design of Experiments

    NASA Technical Reports Server (NTRS)

    Rhode, Matthew N.; DeLoach, Richard

    2005-01-01

    A calibration of a hypersonic wind tunnel has been conducted using formal experiment design techniques and response surface modeling. Data from a compact, highly efficient experiment was used to create a regression model of the pitot pressure as a function of the facility operating conditions as well as the longitudinal location within the test section. The new calibration utilized far fewer design points than prior experiments, but covered a wider range of the facility s operating envelope while revealing interactions between factors not captured in previous calibrations. A series of points chosen randomly within the design space was used to verify the accuracy of the response model. The development of the experiment design is discussed along with tactics used in the execution of the experiment to defend against systematic variation in the results. Trends in the data are illustrated, and comparisons are made to earlier findings.

  4. Wind tunnel investigation of sound attenuation in turbulent flow.

    PubMed

    Andreeva, Tatiana A; Durgin, William W

    2015-08-01

    Wind tunnel investigation of the sound wave attenuation by grid-generated turbulence is performed. The most influential parameters, such as the propagation distance, intensity of turbulent fluctuations and integral scale of the fluctuations are studied using an ultrasonic technique. The results are compared to the theoretical predictions available on the wave statistics. Theoretical predictions are well confirmed and partly extended. It is demonstrated that the ultrasonic technique provides the possibility of reproducing the main effects of atmospheric turbulence on sound propagation while benefiting from isolating the role of various parameters therefore sets of experimental data can be generated under laboratory conditions to benchmark further extensions of theoretical models and numerical simulations. PMID:25917257

  5. Planar Doppler Velocimetry for Large-Scale Wind Tunnel Applications

    NASA Technical Reports Server (NTRS)

    McKenzie, Robert L.

    1998-01-01

    Planar Doppler Velocimetry (PDV) concepts using a pulsed laser are described and the obtainable minimum resolved velocities in large-scale wind tunnels are evaluated. Velocity-field measurements are shown to be possible at ranges of tens of meters and with single pulse resolutions as low as 2 m/s. Velocity measurements in the flow of a low-speed, turbulent jet are reported that demonstrate the ability of PDV to acquire both average velocity fields and their fluctuation amplitudes, using procedures that are compatible with large-scale facility operations. The advantages of PDV over current Laser Doppler Anemometry and Particle Image Velocimetry techniques appear to be significant for applications to large facilities.

  6. Propulsion simulator for magnetically-suspended wind tunnel models

    NASA Technical Reports Server (NTRS)

    Joshi, Prakash B.; Goldey, C. L.; Sacco, G. P.; Lawing, Pierce L.

    1991-01-01

    The objective of phase two of a current investigation sponsored by NASA Langley Research Center is to demonstrate the measurement of aerodynamic forces/moments, including the effects of exhaust gases, in magnetic suspension and balance system (MSBS) wind tunnels. Two propulsion simulator models are being developed: a small-scale and a large-scale unit, both employing compressed, liquified carbon dioxide as propellant. The small-scale unit was designed, fabricated, and statically-tested at Physical Sciences Inc. (PSI). The large-scale simulator is currently in the preliminary design stage. The small-scale simulator design/development is presented, and the data from its static firing on a thrust stand are discussed. The analysis of this data provides important information for the design of the large-scale unit. A description of the preliminary design of the device is also presented.

  7. Monitoring dynamic loads on wind tunnel force balances

    NASA Technical Reports Server (NTRS)

    Ferris, Alice T.; White, William C.

    1989-01-01

    Two devices have been developed at NASA Langley to monitor the dynamic loads incurred during wind-tunnel testing. The Balance Dynamic Display Unit (BDDU), displays and monitors the combined static and dynamic forces and moments in the orthogonal axes. The Balance Critical Point Analyzer scales and sums each normalized signal from the BDDU to obtain combined dynamic and static signals that represent the dynamic loads at predefined high-stress points. The display of each instrument is a multiplex of six analog signals in a way that each channel is displayed sequentially as one-sixth of the horizontal axis on a single oscilloscope trace. Thus this display format permits the operator to quickly and easily monitor the combined static and dynamic level of up to six channels at the same time.

  8. Planar Doppler Velocimetry for Large-Scale Wind Tunnel Testing

    NASA Technical Reports Server (NTRS)

    McKenzie, Robert L.

    1997-01-01

    Recently, Planar Doppler Velocimetry (PDV) has been shown by several laboratories to offer an attractive means for measuring three-dimensional velocity vectors everywhere in a light sheet placed in a flow. Unlike other optical means of measuring flow velocities, PDV is particularly attractive for use in large wind tunnels where distances to the sample region may be several meters, because it does not require the spatial resolution and tracking of individual scattering particles or the alignment of crossed beams at large distances. To date, demonstrations of PDV have been made either in low speed flows without quantitative comparison to other measurements, or in supersonic flows where the Doppler shift is large and its measurement is relatively insensitive to instrumental errors. Moreover, most reported applications have relied on the use of continuous-wave lasers, which limit the measurement to time-averaged velocity fields. This work summarizes the results of two previous studies of PDV in which the use of pulsed lasers to obtain instantaneous velocity vector fields is evaluated. The objective has been to quantitatively define and demonstrate PDV capabilities for applications in large-scale wind tunnels that are intended primarily for the production testing of subsonic aircraft. For such applications, the adequate resolution of low-speed flow fields requires accurate measurements of small Doppler shifts that are obtained at distances of several meters from the sample region. The use of pulsed lasers provides the unique capability to obtain not only time-averaged fields, but also their statistical fluctuation amplitudes and the spatial excursions of unsteady flow regions such as wakes and separations. To accomplish the objectives indicated, the PDV measurement process is first modeled and its performance evaluated computationally. The noise sources considered include those related to the optical and electronic properties of Charge-Coupled Device (CCD) arrays and to

  9. Wind Tunnel Force Balance Calibration Study - Interim Results

    NASA Technical Reports Server (NTRS)

    Rhew, Ray D.

    2012-01-01

    Wind tunnel force balance calibration is preformed utilizing a variety of different methods and does not have a direct traceable standard such as standards used for most calibration practices (weights, and voltmeters). These different calibration methods and practices include, but are not limited to, the loading schedule, the load application hardware, manual and automatic systems, re-leveling and non-re-leveling. A study of the balance calibration techniques used by NASA was undertaken to develop metrics for reviewing and comparing results using sample calibrations. The study also includes balances of different designs, single and multi-piece. The calibration systems include, the manual, and the automatic that are provided by NASA and its vendors. The results to date will be presented along with the techniques for comparing the results. In addition, future planned calibrations and investigations based on the results will be provided.

  10. Impact of Thermal Gradients on Wind Tunnel Force Measurements

    NASA Technical Reports Server (NTRS)

    Hereford, James; Parker, Peter A.; Rhew, Ray D.

    1999-01-01

    In a wind tunnel facility, the direct measurement of forces and moments induced on the model are performed by a force measurement balance. The measurement balance is a precision-machined device that has strain gages at strategic locations to measure the strain (i.e., deformations) due to applied forces and moments. The strain gages convert the strain (and hence the applied force) to an electrical voltage that is measured by external meters. Thermal gradients can complicate the process, however. Thermal gradients on the balance cause differential expansion (or contraction) of various parts of the balance that induce a strain that is detected by the strain gages and is indistinguishable from an external applied force. The thermal gradients can result when testing is done at elevated temperatures or at cryogenic temperatures such as at the National Transonic Facility (NTF) at NASA Langley Research Center (LaRC).

  11. Atmospheric Probe Model: Construction and Wind Tunnel Tests

    NASA Technical Reports Server (NTRS)

    Vogel, Jerald M.

    1998-01-01

    The material contained in this document represents a summary of the results of a low speed wind tunnel test program to determine the performance of an atmospheric probe at low speed. The probe configuration tested consists of a 2/3 scale model constructed from a combination of hard maple wood and aluminum stock. The model design includes approximately 130 surface static pressure taps. Additional hardware incorporated in the baseline model provides a mechanism for simulating external and internal trailing edge split flaps for probe flow control. Test matrix parameters include probe side slip angle, external/internal split flap deflection angle, and trip strip applications. Test output database includes surface pressure distributions on both inner and outer annular wings and probe center line velocity distributions from forward probe to aft probe locations.

  12. Cryogenic wind tunnels: Problems of continuous operation at low temperatures

    NASA Technical Reports Server (NTRS)

    Faulmann, D.

    1986-01-01

    The design of a cryogenic wind tunnel which operates continuously, and is capable of attaining transonic speeds at generating pressures of about 3 bars is described. Its stainless steel construction with inside insulation allows for very rapid temperature variations promoted by rapid changes in the liquid nitrogen flow. A comparative study of temperature measuring probes shows a good reliability of thin sheet thermocouples. To measure fluctuations, only a cold wire makes it possible to record frequencies of about 300 Hz. The use of an integral computer method makes it possible to determine the impact of the wall temperature ratio to the adiabatic wall temperature for the various parameters characterizing the boundary layer. These cases are processed with positive and negative pressure gradients.

  13. Hyper-X Stage Separation Wind Tunnel Test Program

    NASA Technical Reports Server (NTRS)

    Woods, W. C.; Holland, S. D.; DiFulvio, M.

    2000-01-01

    NASA's Hyper-X research program was developed primarily to flight demonstrate a supersonic combustion ramjet engine, fully integrated with a forebody designed to tailor inlet flow conditions and a free expansion nozzle/afterbody to produce positive thrust at design flight conditions. With a point-designed propulsion system, the vehicle must depend upon some other means for boost to its design flight condition. Clean separation from this initial propulsion system stage within less than a second is critical to the success of the flight. This paper discusses the early planning activity, background, and chronology that developed the series of wind tunnel tests to support multi degree of freedom simulation of the separation process. Representative results from each series of tests are presented and issues and concerns during the process and current status will be highlighted.

  14. Transonic wind tunnel test of a supersonic nozzle installation

    NASA Technical Reports Server (NTRS)

    Yetter, J. A.; Evelyn, G. B.; Mercer, C.

    1982-01-01

    The design of the propulsion system installation affects strongly the total drag and overall performance of an aircraft, and the concept, placement, and integration details of the exhaust nozzle are major considerations in the configuration definition. As part of the NASA Supersonic Cruise Research (SCR) program, a wind tunnel test program has been conducted to investigate exhaust nozzle-airframe interactions at transonic speeds. First phase testing is to establish guidelines for follow-on testing. A summary is provided of the results of first phase testing, taking into account the test approach, the effect of nozzle closure on aircraft aerodynamic characteristics, nozzle installation effects and nacelle interference drag, and an analytical study of the effects of nozzle closure on the aircraft.

  15. Incremental wind tunnel testing of high lift systems

    NASA Astrophysics Data System (ADS)

    Victor, Pricop Mihai; Mircea, Boscoianu; Daniel-Eugeniu, Crunteanu

    2016-06-01

    Efficiency of trailing edge high lift systems is essential for long range future transport aircrafts evolving in the direction of laminar wings, because they have to compensate for the low performance of the leading edge devices. Modern high lift systems are subject of high performance requirements and constrained to simple actuation, combined with a reduced number of aerodynamic elements. Passive or active flow control is thus required for the performance enhancement. An experimental investigation of reduced kinematics flap combined with passive flow control took place in a low speed wind tunnel. The most important features of the experimental setup are the relatively large size, corresponding to a Reynolds number of about 2 Million, the sweep angle of 30 degrees corresponding to long range airliners with high sweep angle wings and the large number of flap settings and mechanical vortex generators. The model description, flap settings, methodology and results are presented.

  16. Exploratory flutter test in a cryogenic wind tunnel

    NASA Technical Reports Server (NTRS)

    Cole, S. R.

    1985-01-01

    A model consisting of a rigid wing with an integral, flexible beam support that was cantilever mounted from the wall in the NASA LaRC 0.3-m transonic cryogenic tunnel was used in a flutter analysis study. The wing had a rectangular planform of aspect ratio 1.5 and a 64A010 airfoil. Various considerations and procedures for conducting flutter tests in a cryogenic wind tunnel were evaluated. Flutter onset conditions were established from extrapolated subcritical response measurements. A flutter boundary was determined at cryogenic temperatures over a Mach number M range from 0.5 to 0.9. Flutter was obtained at two different Reynolds numbers R at M = 0.5 (R = 4.4 and 18.4 x 10 to the 6th power) and at M = 0.8 (R = 5.0 and 10.4 x 10 to the 6th power). Flutter analyses using subsonic lifting surface (kernel function) aerodynamics were made over the range of test conditions. To evaluate the Reynolds number effects at M = 0.5 and 0.8, the experimental results were adjusted using analytical trends to account for differences in the model test temperatures and mass ratios. The adjusted experimental results indicate that increasing Reynolds number from 5.0 to 20.0 x 10 to the 6th power decreased the dynamic pressure by 4.0 to 6.5 percent at M = 0.5 and 0.8.

  17. Forced Oscillation Wind Tunnel Testing for FASER Flight Research Aircraft

    NASA Technical Reports Server (NTRS)

    Hoe, Garrison; Owens, Donald B.; Denham, Casey

    2012-01-01

    As unmanned air vehicles (UAVs) continue to expand their flight envelopes into areas of high angular rate and high angle of attack, modeling the complex unsteady aerodynamics for simulation in these regimes has become more difficult using traditional methods. The goal of this experiment was to improve the current six degree-of-freedom aerodynamic model of a small UAV by replacing the analytically derived damping derivatives with experimentally derived values. The UAV is named the Free-flying Aircraft for Sub-scale Experimental Research, FASER, and was tested in the NASA Langley Research Center 12- Foot Low-Speed Tunnel. The forced oscillation wind tunnel test technique was used to measure damping in the roll and yaw axes. By imparting a variety of sinusoidal motions, the effects of non-dimensional angular rate and reduced frequency were examined over a large range of angle of attack and side-slip combinations. Tests were performed at angles of attack from -5 to 40 degrees, sideslip angles of -30 to 30 degrees, oscillation amplitudes from 5 to 30 degrees, and reduced frequencies from 0.010 to 0.133. Additionally, the effect of aileron or elevator deflection on the damping coefficients was examined. Comparisons are made of two different data reduction methods used to obtain the damping derivatives. The results show that the damping derivatives are mainly a function of angle of attack and have dependence on the non-dimensional rate and reduced frequency only in the stall/post-stall regime

  18. Estimation of Unsteady Aerodynamic Models from Dynamic Wind Tunnel Data

    NASA Technical Reports Server (NTRS)

    Murphy, Patrick; Klein, Vladislav

    2011-01-01

    Demanding aerodynamic modelling requirements for military and civilian aircraft have motivated researchers to improve computational and experimental techniques and to pursue closer collaboration in these areas. Model identification and validation techniques are key components for this research. This paper presents mathematical model structures and identification techniques that have been used successfully to model more general aerodynamic behaviours in single-degree-of-freedom dynamic testing. Model parameters, characterizing aerodynamic properties, are estimated using linear and nonlinear regression methods in both time and frequency domains. Steps in identification including model structure determination, parameter estimation, and model validation, are addressed in this paper with examples using data from one-degree-of-freedom dynamic wind tunnel and water tunnel experiments. These techniques offer a methodology for expanding the utility of computational methods in application to flight dynamics, stability, and control problems. Since flight test is not always an option for early model validation, time history comparisons are commonly made between computational and experimental results and model adequacy is inferred by corroborating results. An extension is offered to this conventional approach where more general model parameter estimates and their standard errors are compared.

  19. Comparison of Angle of Attack Measurements for Wind Tunnel Testing

    NASA Technical Reports Server (NTRS)

    Jones, Thomas, W.; Hoppe, John C.

    2001-01-01

    Two optical systems capable of measuring model attitude and deformation were compared to inertial devices employed to acquire wind tunnel model angle of attack measurements during the sting mounted full span 30% geometric scale flexible configuration of the Northrop Grumman Unmanned Combat Air Vehicle (UCAV) installed in the NASA Langley Transonic Dynamics Tunnel (TDT). The overall purpose of the test at TDT was to evaluate smart materials and structures adaptive wing technology. The optical techniques that were compared to inertial devices employed to measure angle of attack for this test were: (1) an Optotrak (registered) system, an optical system consisting of two sensors, each containing a pair of orthogonally oriented linear arrays to compute spatial positions of a set of active markers; and (2) Video Model Deformation (VMD) system, providing a single view of passive targets using a constrained photogrammetric solution whose primary function was to measure wing and control surface deformations. The Optotrak system was installed for this test for the first time at TDT in order to assess the usefulness of the system for future static and dynamic deformation measurements.

  20. Full Scale Wind Tunnel and Seaplane Tow Channel

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Construction progress, studding in Tow Channel office area, Full Scale motor fairing in west exit cone, motor fairing in east exit cone. Propeller and motor fairing for west exit cone. Smith DeFrance described the propellers and motors in NACA TR No. 459. ' The propellers are located side by side and 48 feet aft of the throat of the exit-cone bell. The propellers are 35 feet 5 inches in diameter and each consists of four cast aluminum alloy blades screwed into a cast steel hub.' 'The most commonly used power plant for operating a wind tunnel is a direct-current motor and motor-generator set with Ward Leonard control system. For the full-scale wind tunnel it was found that alternating current slip-ring induction motors, together with satisfactory control equipment, could be purchased for approximately 30 percent less than the direct-current equipment. Two 4,000-horsepower slip-ring induction motors with 24 steps of speed between 75 and 300 r.p.m. were therefore installed. In order to obtain the range of speed one pole change was provided and the other variations are obtained by the introduction of resistance in the rotor circuit. This control permits a variation in air speed from 25 to 118 miles per hour. The two motors are connected through an automatic switchboard to one drum-type controller located in the test chamber. All the control equipment is interlocked and connected through time-limit relays, so that regardless of how fast the controller handle is moved the motors will increase in speed at regular intervals.' (p. 294-295)