Download or read book Flight Measurement of Wall pressure Fluctuations and Boundary layer Turbulence written by Harold R. Mull and published by . This book was released on 1960 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Wall pressure Fluctuations and Pressure velocity Correlations in a Turbulent Boundary Layer written by John S. Serafini and published by . This book was released on 1963 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: This experimental study was carried out at a free-stream Mach number of 0.6 and a Reynolds number per foot of 3.45 x 106. The magnitudes of the wall-pressure fluctuations agree with the Lilley-Hodgson theoretical results. Space-time correlations of the wall-pressure fluctuations generally agree with Willmarth's results for longitudinal separation distances. The convection velocity of the fluctuations is found to increase with increasing separation distances, and its significance is explained. Measurements with the longitudinal component of the velocity fluctuations indicate that the contributions to the wall-pressure fluctuations are from two regions, an inner region near the wall and an outer region linked with the intermittency.
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
Download or read book Measurements of the Fluctuating Pressure at the Wall Beneath a Thick Turbulent Boundary Layer written by W. W. Willmarth, C. E. Wooldridge and published by . This book was released on 1962 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flight Measurements of Pressure Fluctuations in a Turbulent Subsonic Boundary Layer and the Relation with Wall Shear Stress written by K. H. Heron and published by . This book was released on 1966 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Measurements of the Corelation Between the Fluctuating Velocities and the Fluctuating Wall Pressure in a Thick Turbulent Boundary Layer written by C. E. Wooldridge and published by . This book was released on 1962 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Wall Pressure Fluctuations Beneath an Axially Symmetric Turbulent Boundary Layer on a Cylinder written by Chi-Sheng Yang and published by . This book was released on 1969 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of the turbulent pressure field on the outer surface of a 3 inch diameter cylinder were made at a point 24 feet downstream of the origin of the turbulent boundary layer. The root-mean square wall pressure was 2.42 times the wall shear stress. The normalized power spectrum at high frequencies contained twice the energy density of the spectrum beneath a plane boundary layer. The convection speed was the same as that in a plane boundary layer but the eddy size was smaller by a factor of two. The smaller eddy size and unchanged convection speed account for the greater energy in the spectrum at high frequencies. (Author).
Download or read book WALL PRESSURE FLUCTUATIONS BENEATH AN AXIALLY SUMMERTRIC TURBULEN BOUNDARY LAYER ON A CYLINDER written by CHI-SHENG YANG, WILLIAM W. WILLMARTH and published by . This book was released on 1969 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Wall pressure Fluctuations and Pressure velocity Correlations in Turbulent Boundary Layers written by John S. Serafini and published by . This book was released on 1963 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pressure fluctuations of a turbulent layer along a plane boundary were investigated. All measurements were made at a nominal free-stream Mach number of 0.6 and an average Reynolds number per foot of 3.45 x 10 to the 6th power in a wind-tunnel facility specially designed for the purpose. The pressure fluctuations were measured with miniature pressure transducers and the velocity fluctuations with hot-wire anemometers. The rootmean-square magnitudes of the wall-pressure fluctuations agree with the Lilley-Hodgson theoretical results, whereas the mean-square spectra do not agree, except over a small range of frequencies. Measurements of the correlations of the wall-pressure fluctuations with the longitudinal component of the velocity fluctuations indicate that the contributions to the wall-pressure fluctuations are from two regions, an inner region near the wall and an outer region linked with the intermittency. (Author).
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.
Download or read book A Review of Turbulence Measurements in Compressible Flow written by Virgil A. Sandborn and published by . This book was released on 1974 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fluctuation Measurements in Supersonic Turbulent Boundary Layers written by Alan. L. Kistler and published by . This book was released on 1958 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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
Download or read book On the Generation of Wall Pressure Fluctuations for Turbulent Boundary Layers Over Rough Walls written by Thomas E. Burton and published by . This book was released on 1971 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of pressure-velocity correlation in turbulent flow was extended to turbulent boundary layer flow over a roughened wall in the absence of a longitudinal pressure gradient. The results obtained are qualitatively similar to those previously measured over smooth walls. A theory is presented to partially explain the behavior of the measured correlations in both the smooth-wall and rough-wall cases.
Download or read book Comparison of Surface Pressure Fluctuations in a Turbulent Boundary Layer as Measured on Various Flight Vehicles written by A. R. Green and published by . This book was released on 1974 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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:
