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Computation Of The Spectra Of Turbulent Boundary Layer Surface Pressure Fluctuations
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Book Synopsis Computation of the Spectra of Turbulent Boundary Layer Surface- Pressure Fluctuations by : John H. Linebarger
Download or read book Computation of the Spectra of Turbulent Boundary Layer Surface- Pressure Fluctuations written by John H. Linebarger and published by . This book was released on 1972 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Experimental Study of Surface Pressure Fluctuations in a Separating Turbulent Boundary Layer by :
Download or read book An Experimental Study of Surface Pressure Fluctuations in a Separating Turbulent Boundary Layer written by and published by . This book was released on 1987 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Some Features of Surface Pressure Fluctuations in Turbulent Boundary Layers with Zero and Favorable Pressure Gradients by : Brian E. McGrath
Download or read book Some Features of Surface Pressure Fluctuations in Turbulent Boundary Layers with Zero and Favorable Pressure Gradients written by Brian E. McGrath and published by . This book was released on 1987 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Modeling of Turbulent Boundary Layer Surface Pressure Fluctuation Auto and Cross Spectra :. by : Robert Rackl
Download or read book Modeling of Turbulent Boundary Layer Surface Pressure Fluctuation Auto and Cross Spectra :. written by Robert Rackl and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Surface Pressure Fluctuations Produced by Boundary Layer Turbulence by : Sheldon Gardner
Download or read book Surface Pressure Fluctuations Produced by Boundary Layer Turbulence written by Sheldon Gardner and published by . This book was released on 1963 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface pressure fluctuations produced by boundary layer turbulence developed above a rigid plane surface are investigated theoretically. For an incompressible flow which obeys the Navier-Stokes equations, the boundary pressure is determined by a volume integration over quadrupole sources. Three different classes of source terms may be identified. These involve second, third, and fourth order velocity correlations. The contribution of the fourth order or turbulence-turbulence terms to the boundary pressure cross spectral density at high frequencies is obtained. The results show that the turbulence-turbulence boundary pressure sources are located at an effective height, and travel with an effective convection speed, both of which depend upon frequency and the shape of the mean velocity profile. At high frequencies, the pressure spectrum is found to be roughly proportional to the sixth power of the free stream velocity, and to the inverse cube of the frequency. Finally, the effect of the finite size of the transducer upon the measured boundary pressure spectrum is discussed. (Author).
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781720629214 Total Pages :88 pages Book Rating :4.6/5 (292 download)
Book Synopsis Modeling of Turbulent Boundary Layer Surface Pressure Fluctuation Auto and Cross Spectra - Verification and Adjustments Based on Tu-144ll Data by : National Aeronautics and Space Administration (NASA)
Download or read book Modeling of Turbulent Boundary Layer Surface Pressure Fluctuation Auto and Cross Spectra - Verification and Adjustments Based on Tu-144ll Data written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-03 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: The literature on turbulent boundary layer pressure fluctuations provides several empirical models which were compared to the measured TU-144 data. The Efimtsov model showed the best agreement. Adjustments were made to improve its agreement further, consisting of the addition of a broad band peak in the mid frequencies, and a minor modification to the high frequency rolloff. The adjusted Efimtsov predicted and measured results are compared for both subsonic and supersonic flight conditions. Measurements in the forward and middle portions of the fuselage have better agreement with the model than those from the aft portion. For High Speed Civil Transport supersonic cruise, interior levels predicted by use of this model are expected to increase by 1-3 dB due to the adjustments to the Efimtsov model. The space-time cross-correlations and cross-spectra of the fluctuating surface pressure were also investigated. This analysis is an important ingredient in structural acoustic models of aircraft interior noise. Once again the measured data were compared to the predicted levels from the Efimtsov model.Rackl, Robert and Weston, AdamLangley Research CenterTU-144 AIRCRAFT; TURBULENT BOUNDARY LAYER; TUPOLEV AIRCRAFT; MATHEMATICAL MODELS; CIVIL AVIATION; PRESSURE; DATA PROCESSING; DATA REDUCTION; CROSS CORRELATION; AIRCRAFT NOISE; FLIGHT TESTS; POWER SPECTRA; FLIGHT ENVELOPES
Book Synopsis Pressure Fluctuations in Turbulent Boundary Layers by : M. V. Lowson
Download or read book Pressure Fluctuations in Turbulent Boundary Layers written by M. V. Lowson and published by . This book was released on 1965 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Measurement of Turbulent Boundary Layer Induced Surface Pressure Fluctuations by : Creighton Lane
Download or read book Measurement of Turbulent Boundary Layer Induced Surface Pressure Fluctuations written by Creighton Lane and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The turbulent boundary layer (TBL) noise generated inside an aircraft can have a detrimental impact on humans. In an effort to better understand TBL physics and measurement techniques, measurements of the fluctuating wall-pressure beneath a TBL have been performed in an anechoic wind tunnel. The measurements were made using an array of pressure microphones provided by Bombardier Aerospace. Analysis of frequency spectra indicated several shortcomings of the array, namely a low saturation limit and electrical issues, however the low speed spectra agree well with the Goody prediction model. Furthermore, an investigation of the relationship between wall-pressure and velocity fluctuations was performed using a pinhole mounted microphone and simultaneous hot-wire boundary layer measurements. This revealed flow interference from the hot-wire apparatus, obscuring the expected relationships and trends. Several areas of improvement have been identified, including higher saturation limit microphones, LDA for velocity measurements, and increasing rigidity of the experimental setup.
Book Synopsis Calculation of Turbulent Boundary Layer Wall Pressure Spectra by :
Download or read book Calculation of Turbulent Boundary Layer Wall Pressure Spectra written by and published by . This book was released on 1993 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study is an investigation into the suitability of various wavevector-frequency models of turbulent boundary layer wall pressure fluctuations for the prediction of experimental measurements of turbulent boundary layer wall pressure spectra. Three separate models of the wavevector- frequency spectrum proposed by D.M. Chase in 1980 and 1987 are evaluated. The wavevector-frequency spectral models are integrated numerically using a formulation for the point wall pressure spectrum (based on the work of Uberoi and Kovasznay). The representation of the wall pressure spectrum used accounts for the effect of a finite sized transducer on the measured wall pressure spectrum. By accounting for the area averaging effect of finite sized transducers on the measured turbulent boundary layer wall pressure spectra, it was possible to use Chase's rigorous formulations for the wavevector-frequency spectrum instead of the point pressure spectrum representations which assume an infinitely small measurement sensor. Results from the numerical integrations are compared to recent experimental data to determine which model of the wavevector- frequency spectrum most accurately predicts measured turbulent boundary layer wall pressure spectra. Data from experiments using fluids with a wide range of physical properties (air, water, and glycerine) are used for comparison purposes. Using the selected model, new empirical constants are established for use in the model for each fluid under consideration. Justification for use of the new empirical constants is given, and current limitations of the wavevector- frequency models are discussed.
Book Synopsis Modeling of Turbulent Boundary Layer Surface Pressure Fluctuation Auto and Cross Spectra by : Robert G. Rackl
Download or read book Modeling of Turbulent Boundary Layer Surface Pressure Fluctuation Auto and Cross Spectra written by Robert G. Rackl and published by . This book was released on 2005 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Some Results of Experimental Investigations of the Surface Pressure Field Due to a Turbulent Boundary Layer by : M. K. Bull
Download or read book Some Results of Experimental Investigations of the Surface Pressure Field Due to a Turbulent Boundary Layer written by M. K. Bull and published by . This book was released on 1961 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental results for the space-time correlations of the fluctuating pressure field of a turbulent boundary layer are given, and an empirical representation of the pressure field suitable for structural response calculations is presented. Variation with Mach number of r.m.s. pressure as a function of skin friction is given for Mach numbers up to about 1.6. The probability distribution of the pressure fluctuations at a fixed point in the field is found to approximate closely to Gaussian. The acoustic power output from a boundary layer on a larger boundary surface is obtained. Spectra of boundary layer noise in tow jet aircraft are presented and compared with the spectrum of the boundary layer excitation. (Author).
Book Synopsis On Surface Pressure Fluctuations in Turbulent Boundary Layer by : College of Aeronautics (Cranfield, Bedfordshire)
Download or read book On Surface Pressure Fluctuations in Turbulent Boundary Layer written by College of Aeronautics (Cranfield, Bedfordshire) and published by . This book was released on 1960 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Wall Pressure Fluctuations in a Turbulent Boundary Layer by : William W. Willmarth
Download or read book Wall Pressure Fluctuations in a Turbulent Boundary Layer written by William W. Willmarth and published by . This book was released on 1958 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: When a turbulent boundary layer is produced by air flow past a solid surface, the turbulence in the boundary layer can generate a sound field in the free stream and will also induce fluctuating loads on the solid surface. If the surface is flexible, this motion will generate an additional sound field on both sides of the surface. In an initial investigation of the latter form of sound generation, suitable equipment has been developed to measure the fluctuating wall pressure in the turbulent boundary layer. The equipment includes a specially designed low-noise and low-turbulence-level wind tunnel and a small barium titanate transducer and preamplifier combination for frequencies up to 50 kilocycles. The transducer and preamplifier may be useful for other applications. Using this equipment, some of the properties of the wall pressure fluctuations in a turbulent boundary layer have been measured. It was found that the spectrum of the wall pressure fluctuations extended to 50 kilocycles and that the root-mean-square wall pressure was a constant part (0.0035) of the free stream dynamic pressure for 0.2
Book Synopsis Bursts and Pressure Fluctuations in Turbulent Boundary Layers by : Peter Bradshaw
Download or read book Bursts and Pressure Fluctuations in Turbulent Boundary Layers written by Peter Bradshaw and published by . This book was released on 1986 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface pressure fluctuations below turbulent boundary layers were studied, in part, because they can be regarded as 'footprints' of passing turbulent eddies. The pressure fluctuations are formally described by a Poisson equation, implying that the pressure fluctuation at a given point is mathematically represented by the integral of a 'source' term over the whole flow field, with a weighting inversely proportional to the distance of the source from the given point. In turbulent boundary layers, fluctuations were made in a low-speed constant pressure the high-frequency part of the wall pressure fluctuations is generated mainly within the inner layer - say, the first 20% of the boundary layer thickness - and the low-frequency part is generated mainly in the outer layer. Measurements of velocity and surface-pressure turbulent boundary layer well downstream of an extensive region of wall roughness. The turbulence near the wall was representative of a smooth-wall flow, while that in the outer layer was typical of the upper stream rough-wall flow. Comparison with previous measurements on an entirely smooth wall illustrates the relative contributions of the inner and outer layers to the surface pressure fluctuations. Further work has been done to compare the VITA (Variable ge) conditional-sampling algorithm withuctuations were more advanced algorithms. Keywords: Turbulent boundary layer, Noise measurement, Statistical analysis, Surface roughness, and VITA algorithm.
Book Synopsis Flinovia - Flow Induced Noise and Vibration Issues and Aspects by : Elena Ciappi
Download or read book Flinovia - Flow Induced Noise and Vibration Issues and Aspects written by Elena Ciappi and published by Springer. This book was released on 2014-11-23 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow induced vibration and noise (FIVN) remains a critical research topic. Even after over 50 years of intensive research, accurate and cost-effective FIVN simulation and measurement techniques remain elusive. This book gathers the latest research from some of the most prominent experts in the field. It describes methods for characterizing wall pressure fluctuations, including subsonic and supersonic turbulent boundary layer flows over smooth and rough surfaces using computational methods like Large Eddy Simulation; for inferring wall pressure fluctuations using inverse techniques based on panel vibrations or holographic pressure sensor arrays; for calculating the resulting structural vibrations and radiated sound using traditional finite element methods, as well as advanced methods like Energy Finite Elements; for using scaling approaches to universally collapse flow-excited vibration and noise spectra; and for computing time histories of structural response, including alternating stresses. This book presents the proceedings of the First International Workshop on Flow Induced Noise and Vibration (FLINOVIA), which was held in Rome, Italy, in November 2013. The authors’ backgrounds represent a mix of academia, government, and industry, and several papers include applications to important problems for underwater vehicles, aerospace structures and commercial transportation. The book offers a valuable reference guide for all those working in the area of flow-induced vibration and noise.
Book Synopsis Temporal and Spectral Features of Wall Pressure Fluctuations Beneath a Turbulent Boundary Layer by : Carolyn Ceder Karangelen
Download or read book Temporal and Spectral Features of Wall Pressure Fluctuations Beneath a Turbulent Boundary Layer written by Carolyn Ceder Karangelen and published by . This book was released on 1991 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis On Surface Pressure Fluctuations in Turbulent Boundary Layers by : G. M. Lilley
Download or read book On Surface Pressure Fluctuations in Turbulent Boundary Layers written by G. M. Lilley and published by . This book was released on 1960 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
