Experimental investigation into the pulsating flow performance of a turbocharger turbine in the closed and open waste-gate region

Nowadays, turbocharging is considered as a key technology for reducing CO2 emissions in downsized automotive engines. However, more information is still required on compressor and turbine behaviour when working under unsteady flow conditions. The results of an extensive investigation into a small turbocharger turbine fitted with a waste-gate valve are presented in this paper. Measurements were developed at the University of Genoa test facility which allows investigations to be performed under both steady and unsteady flow conditions. Turbine unsteady performance was evaluated at different operating conditions, starting from the measurement of instantaneous parameters (inlet and outlet static pressure, mass flow rate and turbocharger rotational speed). This paper analyses the effect of flow unsteadiness on turbine performance at different pulse frequencies and waste-gate settings.