中文摘要：

本文以完全气体为流动工质,进行离心透平级的气动设计与性能研究。采用数值模拟方法,对所设计的离心透平级进行设计工况及变工况条件下的三维稳态流场分析。结果表明：在设计工况下,流道内的流场合理,流线流畅,气动性能符合预期;在变工况条件下,当转速一定,随着背压的降低,流量缓慢增大,效率先缓慢下降,再迅速下降。随着背压的升高,流量和效率都是先缓慢下降,再迅速下降;涡流的出现会导致变工况点的效率的迅速下降;转速增大对流量几乎没有影响,转速增大可使最佳效率点向压比p2/p1小的方向移动;转速减少对流量也几乎没有影响,转速减少可使最佳效率点向压比p2/p1大的方向移动;进口温度的变化对级效率影响较小,质量流量随进口温度的增大而降低。

英文摘要：

In this paper,the aerodynamic design and performance research of a centrifugal turbine stage were conducted by using perfect gas as working fluid.Based on the CFD simulation method,the analysis of three-dimensional steady-state flow for the designed centrifugal turbine stage was carried out both in design and off-design conditions,and the following results were obtained：In the design condition,reasonable flow field and smooth streamline were presented in the flow path and the aerodynamic performance met well with expectations;In the off-design conditions,when the rotor speed is constant,the mass flow rates slowly increased with the decrease of back pressure,and the efficiency decreased slowly at first,then dropped rapidly.With the increase of back pressure,both of the mass flow rates and efficiency slowly declined at first,then quickly dropped;The appearance of vortex would led to the rapid decline of the efficiency in the off-design conditions;The increase of rotor speed which showed little effect on mass flow rates could drive the best efficiency point move towards to the direction with smaller pressure ratio p2/p1;The reduce of rotor speed which had little effect on the mass flow rates enabled the best efficiency point moved towards to the direction with larger pressure ratio p2/p1;The variation of inlet temperature showed little effect on stage efficiency,while mass flow rates decreased with inlet temperature increases.