Using the model developed by the author for zero-pressure gradient turbulent boundary layers, results are obtained for adverse and favorable pressure gradients. It is shown that when a flexible plate is located in an adverse pressure gradient area, it vibrates more than if it were in a favorable pressure gradient one. Therefore the noise generated by the plate in an adverse pressure gradient is much greater than that due to the plate in a favorable pressure gradient. The effects of Reynolds number and boundary layer thickness are also analyzed and found to have the same effect in both adverse and favorable pressure gradient cases. Increasing the Reynolds number is found to increase the loading on the plate and therefore acoustic radiation. An increase in boundary layer thickness is found to decrease the level of the high frequencies and therefore the response and radiation at these frequencies. The results are in good qualitative agreement with experimental measurements. Frendi, Abdelkader Langley Research Center NAS1-19700; NAS1-96014; RTOP 537-06-37-20...

Measurements of mean flow profiles at several streamwise locations in a supersonic turbulent boundary layer growing under a continuous adverse pressure gradient are reported. Tests were performed at a freestream Mach number of 3, for an adiabatic wall, using two curved ramps designed to produce constant pressure gradient flows. The velocity profile data, when transformed to incompressible coordinates, are in good agreement with Coles universal 'wall-wake' velocity profile and they indicate that the boundary layer is in local equilibrium and essentially independent of upstream history. In addition, the Coles wake parameters and Clauser shape factors, characterizing the transformed profiles, are in accord with the results of low speed correlations of adverse pressure gradient flows. The turbulent transport terms were extracted from the mean flow field data and indicate that for a given ramp, the profile of turbulent shear stress normalized by the wall shear, versus distance from the surface, normalized by the local boundary thickness, is severely distored by the pressure gradient although it is apparently insensitive to local conditions.