Effects of vaneless region length on the performance of a centrifugal compressor with vaned diffuser are studied in this paper. The vaneless region is defined as the space between the impeller outlet and the vaned diffuser inlet. In this work, the studied ratio between the diffuser inlet and impeller outlet is from 1.06 to 1.20. The simulation results show that the variation in the vaneless region has a great impact on the performance of the compressor stage. It is found that the proper extension of vaneless region improves the performance of compressor stage by significantly reducing the separation near shroud and uniformly disturbing flow velocity at impeller outlet and diffuser inlet. Sufficient extension of the vaneless region is necessary to produce beneficial effects, while the excessive extension will instead deteriorate the compressor performance. The mechanism of performance improvement is that reasonable vaneless space length is able to constrain the flow separation and to make the flow more uniform in the diffuser.

研究了无叶片区域长度对带叶片扩压器的离心压缩机性能的影响。无叶片区域定义为叶轮出口和叶片式扩散器入口之间的空间。在这项工作中，扩散器入口和叶轮出口之间的研究比率为1.06至1.20。仿真结果表明，无叶片区域的变化对压缩机级的性能影响很大。发现无叶片区域的适当延伸通过显着减小护罩附近的分离并均匀地干扰叶轮出口和扩散器入口处的流速而改善了压缩机级的性能。为了产生有益的效果，必须充分扩展无叶区域，而过度的扩展会降低压缩机的性能。性能改善的机制是合理的无叶片空间长度能够限制流分离，并使扩散器中的流更均匀。