DL125-9离心压缩机是新型的H型压缩机.试验结果表明,其性能与设计要求有偏差,压比偏低,变工况性能差.为了改善其空气动力性能,本研究对影响压缩机性能较大的扩压器进行了试验研究和分析,通过对四种不同几何参数的方案进行比较,确定了工作范围宽、级效率和压比较高的VD-3扩压器为较好的几何参数匹配.压力恢复比原设计VD-1增大34%,级效率提高3～4％. The centrifugal compressor of DL125-9 is a new type H compressor.The test results show that its performance is deviated from the design requirements, the pressure ratio is too low, the performance of the working condition is poor.In order to improve its aerodynamic performance, Compared with the schemes of four different geometrical parameters, the VD-3 diffuser with wide working range, high level efficiency and high pressure ratio is determined as the better geometry Parameter matching Pressure recovery than the original design VD-1 increased by 34%, level efficiency increased by 3 to 4%.