Unsteady Performance Simulation Analysis of a Waste-Gated Turbocharger Turbine under Different Valve Opening Conditions

An electronic waste-gated turbocharger for automotive application can accurately control the boost pressure and effectively reduce turbo-lag. It can improve the transient responsive performance of engine and the acceleration performance of vehicle, which makes vehicle have a better adaptation to the complex traffic environment. A detailed analysis of aerodynamic working principle of electronic wastegate is the foundation for designing the control strategy of electronic wastegate. Putting turbine with electronic wastegate under unsteady condition that simulates the pulse exhaust gas of engine and studying influences of different valve opening on the performance of turbine has the practical value.

This paper sets fixed and periodical unsteady conditions and adopts numerical methods to explore the performance of turbine in twin-entry turbocharger and the flow loss of bypass. Steady simulation structure is given for reference. The influence and change rule of wastegate valve opening on turbine performance are researched comprehensively. The results show that the nearer the valve opening approximates to full close, the greater the influence on the turbine unsteady performance is, and the bigger the flow loss in per degree is. The flow loss in the turbine and the bypass are evaluated to reveal the mechanism of influence on turbine performance of valve opening and flow loss. This paper is helpful to optimize the structure of electronic actuator and design the control strategy.