径流式透平叶轮内部三元流动的计算方法及其特性分析

NUMERICAL METHOD FOR THREE-DIMENSIONAL INTERNAL FLOWS AND ITS ANALYSIS IN A RADIAL INFLOW TURBINE IMPELLER

基于Ｄｅｎｔｏｎ的对五差分格式，发展了径流式透平叶轮内部三元流动Ｅｕｌｅｒ方程的时间推进有限体积求解方法，并对一个车用增压器径流式透平叶轮的内部流动在多个工况条件下进行了计算分析，揭示了其内流规律，与准三元流动分析结果的比较表明：准三元流动模型由于忽略了流面厚度的变化，相应的流动分析和设计计算都有局限性。因而，对径流式透平叶轮应该采用全三元流动分析方法设计叶道，以求叶轮内流效率及透平性能有较大幅度的改善。

The internal flow in a radial inflow turbine impeller is the most typicaI three-dimensional flow inturbomachinery。In this paper,a time-marching finite-volume methed for Euler equations to solve thethree-dimensional flows in the radial inflow turbine impeller is developed based on Denton' s opposed-difference scheme,and the flow calculation for a vehicle turbocharger turbine impeller,which was in-vestigated previously by quasi three-dimensional flow analysis,is performed under several conditions.The predicted resuIts reveal the complicated three-dimensional internal flow characteristics,and thecomparison between the fully and quasi three-dimensional flows shows that the quasi three-dimensionalflow pattern has its llmitation in both flow analysis and design calculation because of the variation ofstream-surface thickness and the twist of the stream-surfaces.Therefore,in order to improve the flowefficiency of the impeller and the aerodynamic Performance of the turbine,it is necessary to use thefully three-dimensional flow analysis method in the design procedure for the flow passage kf the radialinflow turbine impeller.