Self-oscillation regimes in a liquid jet curtain separating gas regions with different pressures

Abstract

The results of an experimental investigation of the self-oscillation regimes of liquid jet outflow into a plane channel with air injection in its dead end are presented. The effect of the volume of the cavity, or the air cushion, and its thickness (or channel width) on the flow is studied on a wide range of the gas injection rate and the liquid outflow velocity. The self-oscillation flow regimes are realized at a constant pressure of water in the supply tank and a constant mass flow rate of the air injected into the cushion. With increase in the air injection rate the self-oscillation regime realized at lower injection intensities is replaced by a higher-frequency regime. High-speed videofilming shows that the difference from the low-frequency regime consists in the absence of the direct interaction between the out flowing jet and the channel wall. It is found that in both low-frequency and high-frequency regimes the self-oscillation frequency and amplitude are independent of the cushion thickness but the moment of the regime changeover is determined by this parameter. It is established that there exists a threshold value of the cavity volume, behind which the low-frequency regime does not occur at any air injection rates.