Model development of novel wastegate valve design of double scroll turbines utilised for engine-tailored assessment

Despite the shift towards electric vehicles, there is a pressing need to develop efficient solutions to enhance turbocharger performance. For this reason, a novel wastegate design methodology was developed for this research. The concept allows scroll connection to take place for double-entry turbines. The key challenge is to create a design that maintains scroll separation at low engine RPM to achieve high torque, allowing scroll connection at higher engine RPM and reducing the back pressure. A detailed analysis was conducted based on the results of both experimental and computational (CFD) evaluations, and the data was used to enable 1D system-level assessment and optimise the design. This paper develops a new 1D methodology to characterise wastegate and scroll connection interaction. The approach is calibrated against a large data set using a ”scroll–bypass” method and validated against full-stage steady and unsteady data for different degrees of scroll connection. The final stage relates to optimising the scroll connection of a double scroll turbine model in GT-Power for fuel consumption. This optimisation is carried out over key operating points across the engine map.