Accession Number : AD0651130

Title :   THE WALL PRESSURE SPECTRA IN A THICK TURBULENT BOUNDARY LAYER,

Corporate Author : TAGGART (ROBERT) INC FAIRFAX VA

Personal Author(s) : Stevenson,Matthew

Report Date : APR 1967

Pagination or Media Count : 26

Abstract : Results are presented of measurements carried out in a quiet flow water tunnel. Boundary layer characteristics are given for a range in maximum flow velocity between 12 and 22 feet/second, and are in the form of the inner semilogarithmic wall law and the velocity defect law. Variation of the displacement thickness with velocity is also shown. From spectrum level curves it is shown that the intensity level falls at a rate of about 10 db/octave with increasing frequency and for any given frequency, the dependence on flow velocity is about 2 db/foot/second over a wide frequency range. Spectral density data are presented in non-dimensional form which are in agreement with previously reported results at least beyond a certain frequency. Below this frequency, an apparent increase in spectral density with increase in flow velocity indicates the presence of low frequency tunnel vibration. Qualitatively, however, the low frequency results show a tendency for the spectral density values to decrease with decreasing frequency. At the higher frequencies, the results indicate clearly the inability of the finite sized transducer to resolve the small wave-length components of the pressure field. (Author)

Descriptors :   (*TURBULENT BOUNDARY LAYER, PRESSURE), WALLS, THICKNESS, WATER TUNNELS, SPECTROSCOPY, FREQUENCY, TRANSDUCERS, NOISE

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE