Abstract
The effects of the contraction area ratio CR of orifice nozzle on the flow characteristics of the free jet issued from the nozzle are examined. The large vortex structure of submerged orifice water jet is visualized by tracer method and examined the effects of CR on it. The mean and fluctuating velocities of orifice air jet are measured by a single probe and hot-wire anemometry and the effects of CR on them are also examined. CR was changed from 1.00 to 0.11. As a result, (a) the centerline maximum velocity u c/u m (u m: nozzle exit mean velocity) can be presented by u c/ u m=1.9 CR 3 -3.55CR 2+1.38 CR+1.53, and (b) the maximum of u c/u m=1.7 occurs at CR=0.27, and others were made clear.
