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.

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).

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.

Measurements made on some of the characteristics of the turbulent pressure field at the wall of a cylindrical pipe yielded root-mean-square pressure levels, power spectra, longitudinal space-time correlations, and convection velocity over a limited range of Reynolds number. The root-mean-square pressure levels were proportional to the dynamic pressure and when nondimensionalized by use of the dynamic pressure were observed to be independent of the Reynolds number and approximately equal to 0.008 over the Reynolds number range examined. The measurements indicate the existence of an apparent downstrea c nvection of the pressure field at a rate which is approximately the mean discharge velocity of the pipe flow. The pressure field in addition to being convected was also dispersed. Estimates of the scale of the turbulence were obtained. A limited statistical analysis of the pressure time history indicates that the amplitude variation is Gaussian. (Author).