Turbine performance improvement by the multi-objective optimization for variable nozzle vanes of turbocharger

Abstract

This paper focuses on improving the turbine efficiency of a variable geometry system (VGS) of turbochargers for internal combustion engines. The study investigates the shape optimization of the turbine nozzle vane and impeller of VGS through a meta-model-assisted multi-objective optimization. The design parameters of the optimal solution were compared with the baseline model for data and internal flow field analysis to explore which parameters have an impact on performance improvement. It was found that the optimized trailing edge angle of the nozzle vanes allows the exhaust airflow to reach the impeller with the minimum traveling path, and it contributes to mitigating the mixing loss of the flow to the impeller blade. The optimized impeller blade angle leads to an increase in torque and a higher turbine efficiency (> 5%) with the narrow opening, also ensuring a high mass flow in the wide opening. This outcome can contribute to the design and development of high-performance and low-emission turbocharger systems by optimizing the performance of turbine design parameters simultaneously.