Self-oscillatory spouting regimes of plane vertical submerged heavy-fluid jets in setups with near-bottom discharge

New results of the series of experimental and numerical investigations of the self-oscillatory regimes of plane vertical jet spouting from beneath the free surface of a heavy incompressible fluid in reservoirs of limited dimensions are presented. The experiments were performed on a rectangular-in-plan setup with near-bottom regime of fluid discharge. For several widths of the near-bottom orifices in the end walls of the setup the dependence of the self-oscillation period on the jet flow rate is studied. A considerable difference of these dependences from those earlier obtained in the case of the spouting with fluid discharge over a weir is found to exist. On certain ranges of control parameters it is established that the fountain self-oscillation periods are similar in value to those of natural oscillations of standing waves in the setup. A fairly narrow jet velocity range is revealed on which a hysteresis effect, that consists in the difference between the flow-rate-dependences of the self-oscillation period with gradual increase or decrease in the flow rate, is observable. The results of numerical calculations carried out using the STAR-CD software package are in good agreement with the experimental data.