Gasdynamic behaviours of a radial turbine with pulsating incoming flow

This paper investigates turbine performance and gasdynamic behaviours of a radial turbine confronted by pulsating inflow via detailed flow measurement. Firstly, pressure propagation in the volute over circumferential direction is captured by six pressure transducers. The propagation speed is confirmed to be the sum of bulk flow velocity and sonic velocity by the experiment. Local flow parameters also propagate at the same speed with pressure pulse, which indicates that pulsations of the flow parameters are driven by the pulse of pressure. An evident phase-shift is observed between input power and output work, which is mainly resulted from the pulse propagation in the inlet duct. Furthermore, the pressure pulse at rotor inlet is evidently out-of-phase with that at rotor exit, producing a larger hysteresis loop of swallowing capacity. Specifically, the cycle-averaged input work is about 22.2% higher than the case with constant exit pressure. It is found to be resulted from the phase-flip of the pulse at rotor exit due to the gasdynamic behaviour at the interface between the rotor and exit duct, where sudden expansion happens. This paper unveils the gasdynamic behaviours of turbine confronted by pulsating inflow and can have a guide effect for performance enhancement design methodology.