Some Correlations of Theory and Experiment for Developing Turbulent Free Shear Layers

Abstract

This paper presents an extensive review of some recent experimental results for developing turbulent free shear layers in isoenergetic flow with free stream Mach numbers up to eight. Experimental longitudinal variations of a midprofile velocity and a characteristic layer width are compared with corresponding predictions from a recent theory for developing layers and from the well-known asymptotic theory. Using a recent theoretical specification for the variation of spread rate parameter σ with free stream Mach number, it was found that the predictions of the developing layer analysis were in general agreement with measurements. It was demonstrated that the asymptotic theory, in conjunction with the virtual origin technique, can also be utilized to predict developing layer growth. An experimental specification of σ yielded uncertainties ranging from 15 to 50 percent, although the results tended to confirm the general validity of some recent theoretical postulations for the spread rate parameter.