Experimental Characterisation of a Novel Double Scroll Wastegate Connection Valve Design for Turbochargers

The automotive sector is going through a major transition. Despite the rapid onset of electric mobility, developing simple and effective solutions to improve turbocharger performance remains an important task. The present work aims to do so by developing a novel wastegate design methodology which allows scroll connection to take place for doubleentry turbines. The design presented seeks to isolate both turbine inlets when the engine operates at low RPM, achieving high torque, while increasing the flow between the two inlets when the engine operates at high RPM, reducing the back pressure and, thus, the pumping losses. The novel turbine involves cutting back the wall that divides the two wastegate channels, allowing the cross-flow to be regulated. The research aims to capture the performance of the proposed new concept experimentally. To characterise the cross-flow behaviour, a novel test rig was developed using an innovative “scroll-bypass” method to isolate the wastegate from the rotor. The approach has been verified as feasible through preliminary CFD and allows for calculating cross-flows and wastegate mass flows at different operating conditions. The paper describes the new wastegate characterisation strategy and presents the results for 3 different configurations of the cutting-back wall.