TRANSONIC FLOW AROUND A BUTTERFLY VALVE IN PARTIAL OPENING POSITIONS WITH HOMOGENEOUS CONDENSATION OF MOIST AIR

In high-speed flows (such as transonic or supersonic), the expansion of a vapor/carrier gas mixture (moist air) or steam is often so rapid that the flow field gives rise to a spontaneous homogeneous condensation process. As a result, heat released from this condensation affects the associated aerodynamic characteristics. In the present study, the effect of homogeneous condensation of moist air around a circular arc disk butterfly valve in mid-stroke positions of 30° and 45° was investigated numerically, where 0° was the fully open position. The computed results were validated through experiments for both dry and moist air cases. The results showed that the homogeneous condensation of moist air significantly altered the shock wave structure, wake characteristics, and total pressure loss compared to the dry air case. Moreover, the frequency of flow oscillation was reduced in the case of condensation for the partial opening positions of a butterfly valve.