Investigation of Flow Upstream of Orifices

A physical model study is conducted to investigate the flow field upstream of orifices. In particular, new experimental data for the upstream flow pattern resulting from multiple orifices, an orifice near a free surface, and a large orifice (where the pressure gradient across the orifice cannot be ignored) are collected and presented. A new potential flow solution for flow behind orifices is developed to include pressure gradient effects as well as to accurately superpose the solution due to multiple orifices and determine a solution close to orifices. The proposed solution compares well with the measured data for multiple orifices and for an orifice near a free surface. For a large orifice, the skew in the velocity profile in the vertical direction due to the pressure gradient is accurately predicted.