Investigation on the flow angle of a mixed flow turbocharger turbine under steady state operating conditions

Abstract

Turbocharger is widely used in automotive field for the capability to extract or boost the downsizing internal combustion (IC) engine as it has been considered as a way to provide highly efficient of small engine. Turbocharger also reduces the fuel consumption as well as the carbon dioxide (CO2) emission. Turbine is one of the main components of a turbocharger. Generally, this study is mainly focusing on a mixed flow turbine that work under steady flow operation. Numerical work using Computational Fluid Dynamics (CFD) is presented in this report. This report aims to compare the flow angle analysis of three selected cases under steady state flow operating conditions. A 3D modelling on a mixed flow turbine is generated accordingly to ‘Rotor A’ design by using a commercial software of Ansys CFX. Three selected cases were selected in order to compare the flow angle at the mid span circumference location at vane and rotor inlet. The simulation results show the capabilities of the 3D model developed in capturing the trend of available experiment data at turbine speed of 48kRPM. The mixed flow turbine achieves optimum total-to-static efficiency of 74.16 % at velocity ratio of 0.65 with mass flow rate of 0.5kg/s. Besides that, the results shown that the flow angle distribution at the rotor inlet is varied throughout the rotor circumference location between the three cases. Case 2 achieved the optimum incidence angle compared to the other cases thus showing the impact of incidence angle in determining the turbine performance.