I.I.Kozlov, S.A.Ocheretyany, V.V.Prokof'ev Îscillatory regime in liquid jet veil separating gas areas with different pressure |
Applied hydromechanics, Vol. 15 (87) ¹ 1, (2013) |
| In G. V. Logvinovich's monograph "Hydrodynamics of currents with free borders" (in Russian) the general properties of flows of liquid with free boundaries are considered. To them treat as a current with formation of cavities on streamline bodies, and jet flows with the boundaries dividing liquid and gas. Questions of behavior of the non-stationary free borders, raised and studied in the monograph, are actual still and inspire many authors on new researches. Below one of such researches - a problem of creation of the air cushion by means of a jet veil is presented. Presented results of experimental studies for self-oscillating modes of fluid jet discharging in a plane channel with an air cushion. Investigated effect on the flow from the air cavity volume and thickness, width of the channel in a wide range of magnitude of jet rate and amount of gas discharge. Oscillatory flow regimes were realized under constant water pressure in the pressure tank and a constant mass flow rate of the blower to the air cushion. It was found that the previously studied low-frequency mode exists in a certain range of values of gas flow rate to the cavity, with the range depending on the cavity volume. It is shown that in some cases this mode is replaced by a high-frequency oscillatory regime with low amplitude, and in transitional range of air flow-rate both modes are simultaneously presented (there is an intermittency). Video recording of high-frequency regime has shown that unlike in the low-frequency regime there is no direct interaction between the outflowing jet with the channel wall. We found that in both modes the oscillation characteristics of the flow (frequency, amplitude) are independent of the thickness of the cushion (the channel width). However, the regime change event significantly depends on the thickness of the cushion. |
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KEY WORDS: cavitation, jet, self-oscillations, Rayleigh-Taylor's instability, high-speed video |
| TEXT LANGUAGE: English |