Effect of non-equilibrium homogeneous condensation on the self-induced flow oscillation of supersonic impinging jets

Supersonic impinging jets are characterized by a strong coupling between the flow and acoustic fields with a self-contained feedback mechanism. This self-induced oscillatory flow make thermal and mechanical loading more severe and produces severe noise at discrete frequencies, which may cause sonic fatigue of the structures and also may damage various instruments and equipments. These loads are also accompanied by dramatic lift loss, severe ground erosion and hot gas ingestion. To control the flow it is needed to clarify the characteristics and mechanism of oscillation. However, in actual jet flows, the working gas may contain condensable gas such as steam or moist air. In these cases, non-equilibrium condensation may occur at the region between nozzle exit and an object. The jet flow with non-equilibrium condensation may be quite different from that without condensation. Therefore, the numerical investigation of the self-induced flow oscillation of supersonic impinging moist air jet was carried out in this study. Moreover, this paper aims to clarify the effect of non-equilibrium condensation on the characteristic of pressure fluctuations during the impingement of under-expanded supersonic moist air jets on a perpendicular flat plate. (C) 2010 Elsevier Masson SAS. All rights reserved.