Experimental Study on the Flow Characteristics of Streamwise Inclined Jets in Crossflow on Flat Plate

Abstract

Experimental study has been conducted to investigate the flow characteristics of streamwise 35 deg inclined jets, injected into a turbulent crossflow boundary layer on a flat plate. Flow is visualized by schlieren photographs for both normal and inclined jets to determine the overall flow structure with the variation of the velocity ratio. A three-dimensional velocity field is measured for two velocity ratios of 1.0 and 2.0 by using a five-hole directional probe. The visualization study shows that the variation of the injection angle produces a significant change in the flow structure. It is recognized that the jet flow is mainly dominated by the turbulence for a small velocity ratio, but it is likely to be influenced by an inviscid vorticity dynamics for a large velocity ratio. Such a trend prevails in the streamwise inclined injection, compared with the normal injection. A pair of bound vortices accompanied with a complex three-dimensional flow is present in the downstream region of the jet exit as in the case of the normal injection, although its magnitude and range are different, and the strength of the bound vortex is strongly dependent on the velocity ratio. The interface between the jet and the crossflow is identified from the vorticity distribution.