An Experimental Investigation Into the Breakdown of Low Reynolds Number Pulsed Flows at a Pipe Orifice

Abstract

An experimental investigation into the behavior of pulsed vortex flows in water at a pipe orifice is outlined. An experimental apparatus is described whereby flow pulsations are generated using an electronically controlled motor-piston arrangement. Preliminary investigations are made into the unpulsed system to determine the natural vortex shedding frequency for various Reynolds numbers and orifice diameters. The downstream development of initially axisymmetric, periodically pulsed vortices shed from the orifice plate are then examined. The growth, evolution, and eventual breakdown of the initially axisymmetric vortices are investigated for a range of flow control parameters. Various flow regimes are discerned and an attempt is made to categorize them.