凝縮衝撃波のパッシブコントロールに関する数値解析 : 定常凝縮衝撃波の場合 : 流体工学,流体機械

A rapid expansion of moist air or steam through supersonic nozzle often leads to nonequilibrium condensation shock. Depending on the heat amount released by condensation of water vapour, the flow is highly subject to a periodic oscillation of condensation shock in the nozzle. The unsteadiness of the condensation shock is always associated with several kinds of instabilities as well as noise and vibration of the flow system. In this paper, a passive technique using a porous wall with a plenum cavity underneath is applied for the purpose of alleviation of the condensation shock oscillations in a supersonic nozzle. A droplet growth equation was incorporated into two-dimensional Navier Stokes equation systems. Computations are carried out using a 3rd-order MUSCL type TVD finite difference scheme with a 2nd-order fractional time step. As a result, the oscillations of the condensation shock wave are completely suppressed by the present passive control method.