An Experimental Investigation of a Turbulent Cylindrical Wall Jet Equipped with Front-Facing Step : Separation and Reattachment Properties of Wall Jet Flow

This paper deals with an experimental study of a turbulent cylindrical wall jet with a front-facing step equipped at an arbitrary location on the cylindrical wall, in order to disturb the flow near the wall and to cantrol the thickness of the wall shear layer. This report is mainly concerned with our search for the effects on the separation and reattachment properties of the jet flow in the region before and after a step with various heights and locations. The variations in the static pressures on the cylindrical wall surface, jet half-widths and boundary layer thicknesses in the downstream direction were examined. The relationships among the separation point from the cylindrical wall, the reattachment point and the nozzle-step distance were obtained. The results were compared with those already obtained for an ordinary cylindrical wall jet without the step. Furthermore, the flow patterns in the x-y plane normal to the wall in the region before and after the step were visualized by an oil film method.