Transonic moist air flow around a symmetric disc butterfly valve with non-equilibrium condensation

Transonic flow around a symmetric disc butterfly valve is associated with the appearance of shock waves on valve surfaces. In this case, the interaction between shock waves and boundary layers becomes complex and thus generates the flow-induced aerodynamic instability. In the transonic or supersonic flow where vapour is contained in the main flow, the rapid expansion of the flow may give rise to non-equilibrium condensation. In the present study, the effect of non-equilibrium condensation of moist air on the shock-induced flow field oscillation around a butterfly valve was investigated numerically. The results showed that in cases with non-equilibrium condensation, the flow field aerodynamic instabilities such as root mean square of pressure oscillation and shock-induced oscillation frequency are reduced significantly compared with those without the non-equilibrium condensation. Moreover, the total pressure loss increases and the vortex shedding frequency is reduced with non-equilibrium condensation.