Passive control applied to Prandtl–Meyer expansion flow with homogeneous condensation

Prandtl–Meyer expansion flow with homogeneous condensation is investigated experimentally and by numerical computations. The steady and unsteady periodic behaviors of the diabatic shock wave due to the latent heat released by condensation are considered with the practical purpose of application to the condensing flow through steam turbine blade passages. A passive control method using a porous wall and cavity underneath is applied to control the diabatic shock wave. Two-dimensional, compressible Navier–Stokes with the nucleation rate equation are numerically solved using a third-order TVD (Total Variation Diminishing) finite difference scheme. The computational results reproduce the measured static pressure distributions in Prandtl–Meyer expansion flows with condensation, without and under control condition. From both the experimental and computational results, it is found that the magnitude of steady diabatic shock wave can be considerably reduced by the present passive control method. For no passive control, the diabatic shock wave due to the heat released by condensation oscillates periodically with a frequency of 2.40 kHz. This unsteady periodic motion of the diabatic shock wave can be completely suppressed using the present passive control method.