中文摘要：

离心式涡轮增压器透平具有与传统透平不一样的结构,本文对某一小流量、高转速、小轮径的离心式透平进行一维气动设计、三维流场模拟与优化以及变工况性能研究。首先,对流体工质以及流动过程进行简化处理,获得一维气动设计的结果;接着,采用计算流体力学软件对离心透平级进行数值模拟,通过改变叶片数目、叶片厚度、中弧线形状等进行叶型优化,获得更合理的流场;最后,分析不同转速、不同流量（背压）下离心式透平的变工况性能。

英文摘要：

The structure of centrifugal turbine of turbocharger is different from the traditional turbine＇s, in this paper, one dimensional pneumatic design, three dimensional flow field simulation and optimization, and variable condition performance will be studied for a small flow rate, high rotating speed and small wheel diameter centrifugal turbine. First of all, the result of one dimensional pneumatic design can be obtained by simplifying the fluid medium and flow process; Then, the numerical simulation and optimization of centrifugal turbine can be conducted adopting the computational fluid dynamics software by changing the leaf number, leaf thickness, and the arc shape of leaf to get a more reasonable flow field; Finally, the result of centrifugal turbine off-design performance under different rotational speed and different flow rate（back pressure） will be analyzed.