Thoughts on Compressible Turbulent Boundary Layers.

A qualitative discussion on compressibility effects on turbulence. An attempt is made to extract the main features of supersonic and hypersonic turbulent boundary layers from the information available and to examine the calculation techniques and transformation methods used for predicting behavior. These predictions include estimations of mean velocity and temperature distribution. In the absence of a theory for compressible or even incompressible turbulent boundary layers, most analytical studies approach the problem by reducing it essentially to the problem of an incompressible fluid. A critical examination is made in terms of both the direct approach and the transformation method. Finally, some experiments are recommended to help generate a more consistent empirical formulation of the hypersonic boundary layer problem and improve present methods of measurement regarding mean velocity and mean temperature distributions. 16 pp. (KB)