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Turbocharging industry mainly employ steady method in the design and development process in present. However, the unsteady method is becoming more important for the exploration of the advanced turbocharging technique. This paper discusses the influences of A/R value on unsteady performances of a double-entry turbocharger turbine. In the study, numerical simulation has been done by ANSYS CFX software, The turbine have three kinds of A/R values that change in order, and the three schemes has the same unsteady flow boundary conditions. The simulation results show that the unsteady turbine performances have the characteristics loops representing filling and emptying effects. And the unsteady performances of the three schemes have some regular differences. The mean unsteady turbine efficiency decreases with increasing A/R value in the involved range, but the overall entropy of the turbine in a pulse period has no significant differences.

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.