Numerical modelling of a supersonic axial turbine stator

In order to improve the turbocharging process, a supersonic axial turbine stator was modelled numerically with a pulsatile inlet mass flow. The main objectives of the study were to find out how pulsation affects the flow field and the performance of the stator. At the beginning of the study, a supersonic turbine stator was modelled using three different techniques: quasi-steady, time-accurate with constant boundary conditions and time-accurate with a pulsatile inlet mass flow. The time-averaged and quasi-steady flow fields and performance were compared, and the flow field and stator performance with a pulsatile inlet mass flow was studied in detail at different time-steps. A hysteresis-like behaviour was captured when the total-to-static pressure ratio and efficiency were plotted as a function of the inlet mass flow over one pulse period. The total-to-static pressure ratio and efficiency followed the sinusoidal shape of the inlet flow as a function of time. It was also concluded that the stator efficiency decreases downstream from the stator trailing edge and the amplitude of the pulsating mass flow is decreased at the stator throat.