无叶扩压器半径比对内部流动影响的研究

Influence of Radius Ratio of Vaneless Diffuser on Internal Flow

无叶扩压器是离心压气机的重要部件,研究其内部流场掌握其流动特点,对于提升扩压器性能及了解失速诱发具有重要意义。采用三维数值模拟方法以更准确真实地展示不同宽比的小型离心压气机无叶扩压器内部流场的演化规律。采用Ansys 15.0软件对离心压气机进行了模型设计,网格划分和数值模拟并对模拟结果进行分析。结果表明:半径比的改变对流场的流动特性影响较小而对压气机的流动稳定性影响较大,半径比越小稳定性越高;失速发生的标志是只有当回流区延伸至扩压器出口处;静压升系数在失速先兆的发生时刻出现最大值。

The vaneless diffuser is an important part of the centrifugal compressor. Studying its internal flow field to get its flow characteristics is of great significance to enhance the performance of diffuser and understand the mechanism of the induced stall. The three-dimensional numerical simulation method is used to show the evolution of the internal flow field of the vaneless diffuser in a small centrifugal compressor with different width ratio. Software Ansys 15. 0 is applied to model the centrifugal compressor,partition mesh,implement numerical simulation and analyze simulation results. The results show that the change in radius ratio has little effect on the flow characteristics of the flow field while it shows a greater effect on the flow stability of the compressor： the smaller the radius ratio,the higher the stability.The indication of occurrence of stall is that only when the return zone extends to the diffuser exit,and the static pressure rise coefficient appears at the time of occurrence of stall precursor.