An Experimental and Theoretical Investigation Of the Interaction of a Turbulent Free Shear Layer with the Rear Edge of a Hole

摘要

The report presents the results of an investigation of the characteristics of the free jet which is formed within a cavity when an incompressible turbulent free shear layer impinges on the downstream edge of a hole. Experiments were performed in a subsonic wind tunnel using a cavity with variable hole geometry and impingement distance. Measurements of the stagnation pressure in the jet impingement region were used to determine the direction of the free jet relative to the original flow direction. In addition, the pressure measurements, supplemented by photographs of a cotton tuft plate, provided details of the geometry of the free jet at impingement. An equation was developed relating the turning angle of the flow, based on the center of the jet at the jet origin, to the ratio of hole thickness to shear layer thickness below the dividing streamline. The experimental data showed agreement with theory. An extension of the theory to the compressible case was developed. (Author)