While passenger vehicle engines are evolving in line with the electrifications of powertrains, more efficient turbochargers are needed than ever before to comply with stricter fuel efficiency regulations and to improve engine performance. In this report, focusing on the fact that turbochargers mounted on engines are driven under exhaust pulsation, we developed a new turbine scroll shape that effectively utilizes the unsteadiness of exhaust pulsation, and measured its effect on the engine bench. As a result, we found hysteresis characteristics of instantaneous turbine performance with respect to the turbine pressure ratio through unsteady turbine performance measurements under exhaust pulsation and large-scale unsteady flow analysis, and a non-linear A/R scroll with reduced scroll volume while maintaining its steady-state flow characteristics was developed, thereby achieving an improvement in the fuel efficiency performance of the engine.
