FLOW CHARACTERISTICS AROUND A CIRCULAR CYLINDER WITH A SLIT - 1. FLOW CONTROL AND FLOW PATTERNS.

Abstract

Experimental investigations on the flow characteristics around a circular cylinder with a slit have been carried out. Flow visualization, hot-wire measurements of the wake flow and the distributions of the static pressure coefficients around the cylinder have been made. The experiments were carried out in the Reynolds number region of 13800 to 52000 for two slit ratios of s/d equals 0. 080 and 0. 185. Three different typical flow patterns were found for the inclination of the slit beta . For 0 degree less than equivalent to beta less than equivalent to 40 degree , the self-injection into the wake was observed. In this case, the base pressure rose and vortex formation region moved downstream. For 40 degree less than beta less than 60 degree , the effect of the slit was little. For 60 degree less than equivalent to beta less than equivalent to 90 degree , boundary layer suction was observed periodically with a period of the shed vortices. In this case, the base pressure coefficient dropped and the shedding frequency decreased.