Air Entrainment in Ventilated Cavities: Case of the Fully Developed “Half-Cavity”

Abstract

Experimental results are given concerning the behavior of the so called “half-cavity” which is formed by a plane water jet, initially horizontal, projected over a small step at the bottom of a channel. The relation between the air flow rate and the cavity pressure is given particular consideration: the influence of geometrical or dynamic parameters on this relation is studied and it is found that the dominant role is played by the Froude number and the cavitation number. Other results concern cavity pulsation frequency and cavity length. Some theoretical considerations concerning the flow geometry are necessary to identify the gravity effect for the case where the cavity is long compared to the height of the step.