Abstract:
The characteristics of pressure pulsations on a flat semi-infinite barrier impinged by a supersonic underexpanded jet are investigated. The Mach number at the nozzle exit is M$_a$ = 1, the degree of underexpansion is $n$ = 2, 1, and the distance from the nozzle exit to the barrier is h/D$_a$ = 2 $\div$ 15 (D$_a$ is the nozzle exit diameter). It is shown that tangential injection of six microjets can significantly reduce pressure pulsations on the barrier. The mass flow through all microjets is 0,3% of the mass flow through the main jet. It is established that when h/D$_a$ < 3, a self-oscillatory mass-flow regime of jet-barrier interaction occurs; when 3 < h/D$_a$ < 8, a self-oscillatory regime with acoustic feedback takes place; and when h/D$_a$ > 8, the turbulent aperiodic interaction regime is realized.
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