EFFECT OF MICROJETS ON THE PRESSURE FLUCTUATIONS OF A SUPERSONIC JET INTERACTING WITH A PERFORATED OBSTACLE
N.P. Kiselev, V.I. Zapryagaev
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch of the Russian Academy of Sciences (ITAM SB RAS), Novosibirsk, Russia
Keywords: supersonic jet, microjet, impinging jet, perforated obstacle, pressure fluctuation, self-sustained oscillation
Abstract
Results of measurements of wall pressure fluctuations generated during the interaction of a supersonic underexpanded jet (with microjets at its nozzle exit) with an obstacle containing a coaxial orifice are presented. It is found that, within a certain range of linear parameters, microjet injection into the main supersonic jet reduces the amplitude of self-sustained oscillations caused by acoustic feedback between the nozzle and the obstacle. Outside this range, however, the presence of microjets does not significantly reduce the pressure fluctuations near the nozzle exit caused by periodic variations in the gas mass flow rate through the central orifice.
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