EFFECT OF A HOLE IN AN OBSTACLE ON THE PRESSURE FLUCTUATION CHARACTERISTICS OF AN UNDEREXPANDED IMPINGING JET
N.P. Kiselev, I.N. Kavun, A.A. Pivovarov
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Keywords: underexpanded jet, impinging jet, perforated obstacle, self-sustained oscillation, pressure fluctuation
Abstract
The flow structure and pressure fluctuation characteristics generated when a supersonic underexpanded jet impinges on a flat semi-infinite obstacle with a coaxial hole are investigated. Different interaction regimes are found to arise depending on the hole diameter and the distance from the nozzle exit to the obstacle. The presence of a hole in the obstacle is found to significantly intensify wall pressure fluctuations for nozzle-to-obstacle distances in the following range: h/Da = 1-4. In the case where h/Da = 4-15, the interaction regimes are similar to those observed for a jet impinging on a solid (impermeable) obstacle.
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