Experimental investigation of turbulent flow through single-hole orifice placed in a pipe by means of time-resolved Particle Image Velocimetry and unsteady pressure measurements

Abstract

The flow passing through a sharp-edged orifice is studied using two experimental techniques over a pipe Reynolds number range of 4000 to 27000. The flow separates at the orifice inlet and is accelerated through its hole in the form of a confined jet. For a given orifice, the mean reattachment length is found to remain fairly independent of the inflow Reynolds number. Velocity and pressure fluctuations attain peak values in regions lying upstream of the mean reattachment point. Under the conditions tested, the orifice jet shows a low frequency flapping motion which was observed to occur at a Strouhal number 0:02 based on the orifice jet velocity and the difference in internal diameters of the pipe and orifice.Aerodynamic