Influence of trailing-edge curve on the performance of radial turbine in turbocharger

Abstract

To combat climate change and promote sustainable engine development, the optimization of the turbocharger development process is necessary to decrease emissions and increase fuel economy. This paper presents the influence of trailing edge curves on the performance of the significantly small radial turbine impeller of an automotive turbocharger used in a 0.8-L two-cylinder gasoline engine by comparing numerical analysis results under two boundary conditions: a constant pressure ratio and constant mass flow rate. The curve of a trailing edge depends on several parameters; however, in this study, the exponent (n) was selected to modify the turbine impeller trailing edge profile, as it exhibits a more significant influence on the curve than other parameters. Hence, computational fluid dynamics (CFD) analyses were conducted on the radial turbine for various trailing edge curves under a constant pressure ratio and constant mass flow rate, and the results were compared. The results indicated that the efficiency improvement was negligible under the pressure ratio and mass flow rate conditions due to inadequate alterations. Nevertheless, a significant shaft power improvement was observed based on changes in the trailing edge curve under a constant pressure ratio. In contrast, the same changes caused a considerable decrease in the shaft power under a constant mass flow rate.