Download or read book Noise Generation in Transonic Wind Tunnels written by M. O. Varner and published by . This book was released on 1975 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: In an attempt to determine the parameters characterizing the noise environment in transonic tunnels, noise-generating mechanisms for porous-wall tunnels with 60-deg inclined holes were isolated and studied. The noise environment in the test section is separated into three distinct parts: the noise due to jet flow through the porous walls, a wall hole-tunnel resonance phenomena, and the turbulent boundary layer on the test section walls and in the diffuser. Each part is analyzed separately for the effects of aerodynamic and geometric flow constraints on the frequency and power characteristics. The contribution of each of the acoustic models to the test section free-stream fluctuating pressure level is also examined.
Download or read book Noise Generation in Transonic Wind Tunnels written by and published by . This book was released on 1975 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In an attempt to determine the parameters characterizing the noise environment in transonic tunnels, noise-generating mechanisms for porous-wall tunnels with 60-deg inclined holes were isolated and studied. The noise environment in the test section is separated into three distinct parts: the noise due to jet flow through the porous walls, a wall hole-tunnel resonance phenomena, and the turbulent boundary layer on the test section walls and in the diffuser. Each part is analyzed separately for the effects of aerodynamic and geometric flow constraints on the frequency and power characteristics. The contribution of each of the acoustic models to the test section free-stream fluctuating pressure level is also examined.
Download or read book Noise Generation in Transonic Wind Tunnels written by and published by . This book was released on 1975 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In an attempt to determine the parameters characterizing the noise environment in transonic tunnels, noise-generating mechanisms for porous-wall tunnels with 60-deg inclined holes were isolated and studied. The noise environment in the test section is separated into three distinct parts: the noise due to jet flow through the porous walls, a wall hole-tunnel resonance phenomena, and the turbulent boundary layer on the test section walls and in the diffuser. Each part is analyzed separately for the effects of aerodynamic and geometric flow constraints on the frequency and power characteristics. The contribution of each of the acoustic models to the test section free-stream fluctuating pressure level is also examined.
Download or read book A Study of Narrow Band Noise Generation by Flow Over Ventilated Walls in Transonic Wind Tunnels written by James P. Woolley and published by . This book was released on 1973 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report is concerned with the problem of environmental noise in transonic wind tunnels with ventilated, or perforated, walls. A brief critical review of past experimental investigations of such sounds is given. It is indicated that the instability of the separated shear layer over the cavities in a perforated wall should be the main agency for sound generation. A stability analysis of a nonparallel shear flow is undertaken. Relations such as the Strouhal numbers and minimum breadths, are given in terms of wind-tunnel aerodynamic parameters. (Author Modified Abstract).
Download or read book Turbulence Measurements and Noise Generation in a Transonic Cryogenic Wind Tunnel written by Dwaine O. Griffith and published by . This book was released on 1989 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Perforated Wall Noise in the AEDC PWT 16 ft and 4 ft Transonic Tunnels written by O. P. Credle and published by . This book was released on 1971 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report presents the results of recent studies of noise in Propulsion Wind Tunnel (16T) and Aerodynamic Wind Tunnel (4T). Noise levels in the free stream and at the test section wall were measured in both tunnels as a function of Mach number, Reynolds number, wall angle, and wall porosity. In Tunnel 4T, free-stream noise characteristics were also evaluated with solid (taped) test section walls. Test results revealed that the perforated test section wall holes generate discrete frequency, high energy noise. In Tunnel 16T, there is a critical Mach number range in which a wall hole frequency. Test section noise levels were found to vary slightly with wall angle and significantly with Mach number and wall porosity. The wall porosity corresponding to the minimum noise levels was found in Tunnel 4T. (Author).
Download or read book An Experimental Evaluation of Test Section Noise in Transonic Wind Tunnels written by Dean F. Long and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flow Generation Properties of Five Transonic Wind Tunnel Test Section Wall Configurations written by R. L. Parker (Jr.) and published by . This book was released on 1975 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of Techniques to Suppress Edgetones from Perforated Wind Tunnel Walls written by and published by . This book was released on 1975 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aerodynamic noise emitted by perforated walls in transonic wind tunnels has been under study for several years at AEDC. This report presents a summary of recent experimental tests to suppress perforated wall noise in transonic test sections. The mechanism of noise generation from perforated walls having 60-deg inclined holes is the edgetone phenomenon where the shear layer over each hole interacts with the trailing edge to produce intense tones at discrete frequencies. Noise reduction was achieved with several modified wall samples in the 6-in. tunnel at resonance conditions.
Download or read book Evaluation of Flow Quality in Two Large NASA Wind Tunnels at Transonic Speeds written by William D. Harvey and published by . This book was released on 1980 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Noise Environment in the NLR Transonic Wind Tunnel HST written by R. Ross and published by . This book was released on 1974 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study of Acoustic Disturbances and Means of Suppression in Ventilated Transonic Wind Tunnel Walls written by N. Sam Dougherty and published by . This book was released on 1977 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation of acoustic disturbances and means of suppression from ventilated transonic wall samples was performed in a low-background-noise research tunnel at AEDC. Configurations for ventilation investigated were longitudinally slotted walls, with and without baffles in the slots, slats versus round rods, and perforated walls with normal or inclined circular holes with varied hole sizes and varied diameter/wall thickness ratio. Comparative acoustic data were acquired over a broad range of subsonic Mach numbers. Several of these wall configurations were found to emit intense, discrete whistling noise with overall root-mean-square amplitudes as large as five percent of the free-stream dynamic pressure. In all cases except one, suppressed noise levels not exceeding 0.75 percent of the free-stream dynamic pressure were achieved compared to a background noise level for the tunnel of approximately 0.47 percent with solid test section walls. Noise suppression was accomplished by means of appropriate devices added to the wall samples which could have application to actual transonic wind tunnel test sections. (Author).
Download or read book Influence of Wind Tunnel Noise on the Location of Boundary layer Transition on a Slender Cone at Mach Numbers from 0 2 to 5 5 written by N. Sam Dougherty and published by . This book was released on 1980 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was conducted to investigate the effects of wind tunnel noise on the location of boundary-layer transition. The study was carried out by conducting experiments on a particular slender, highly polished cone having an included angle of 10 deg. Wind tunnel noise levels were measured in the test section by flush-mounted microphones imbedded in the cone surface. The measurement of boundary-layer transition location was made using either a traversing pitot pressure probe in contact with the cone surface or the flush-mounted microphones. The experiments were carried out in 23 different subsonic, transonic, and supersonic wind tunnels over a range of Mach numbers from 0.2 to 5.5 and a unit Reynolds number range from 1.0 to 7.0 million per foot, the bulk of the data being obtained for a range from 2.0 to 4.0 million per foot. The results clearly show a strong influence of wind tunnel noise on boundary-layer transition location correlatable with overall root-mean-square noise levels. Because the noise level generally varied with Mach number and unit Reynolds number, the unit Reynolds number was found to have little effect on transition Reynolds number. (Author).
Download or read book Fluid Motion Problems in Wind Tunnel Design written by ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT PARIS (France) and published by . This book was released on 1973 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Report, is issued as a complementary document to Advisory Report 60 of the Large Wind Tunnels Working Group. It contains six papers prepared for the Working Group, dealing with influence of free-stream Reynolds Number on boundary layer transition on an infinite swept wing, prediction of transition on shared wings, the need for high Reynolds Number transonic tunnels, the influence of free-stream turbulence on a turbulent boundary layer in subsonic testing, effects on model results due to turbulence and noise, and the design of ventilated walls with special emphasis on noise generation. (Author).
Download or read book The Analysis of Noise Generation and Air Flow in the RMIT Industrial Wind Tunnel written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modification of the Ames 40 By 80 Foot Wind Tunnel for Component Acoustic Testing for the Second Generation Supersonic Transport written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-05 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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. Schmitz, F. H. and Allmen, J. R. and Soderman, P. T. Ames Research Center RTOP 505-38-13...
Download or read book An Experimental Investigation of Techniques to Suppress Edgetones from Perforated Wind Tunnel Walls written by N. Sam Dougherty (Jr.) and published by . This book was released on 1975 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
