针对某采用EGR技术国六排放发动机低速性能不足的问题，对压气机叶轮从叶轮平均子午型线和叶片载荷分布两个方面进行了气动性能优化，并采用NUMECA三维流体仿真软件进行了仿真分析对比，结果显示优化后压气机压比及效率均得到提高，其中峰值效率提升了3个百分点。通过对压气机流场分析发现：新叶轮沿流向方向静压增长非常均匀，降低了流动损失，且在叶顶间隙区域损失减少。流体经叶轮出口流出后掺混损失较低，使得流体在扩压器中扩散损失降低。对新压气机进行了压气机台架特性测试，验证了优化设计方案的可行性。考虑到发动机注重低速性能及EGR需求，将原增压器涡轮箱流道A/R减小8%后，与新压气机匹配并在发动机台架上进行试验，结果显示发动机低速扭矩比客户要求值最大提升1.3%,低速油耗最大降低1.7%，中低转速下压差均略优于目标压差值，发动机性能和EGR水平整体满足了主机厂客户的要求。

In view of the low speed performance shortage of China 6 engine with EGR, the aerodynamic performance optimization of compressor impeller was conducted from the average meridian profile of impeller and the load distribution of blade aspects. The simulation analysis and comparison were further carried out by using NUMECA 3D fluid simulation software. The results show that the compressor pressure ratio and efficiency  improve and the peak efficiency increases by 3% after optimization. According to the analysis of flow field, it is found that the static pressure of new impeller increases evenly along the flow direction, which reduces the flow loss. The loss in the tip clearance area also reduces. The mixing loss of fluid through the outlet of impeller is low, which makes the diffusion loss of fluid in the diffuser reduce. The feasibility of design scheme is finally verified by the performance test on the compressor bench. Considering the more attention to low speed performance and EGR demand, the turbine volute A/R reduces by 8% and matches with the new compressor, and then the test was conducted on the engine bench. It indicates that the low speed torque of engine increases by 1.3%, the low speed fuel consumption reduces by 1.7%，and the pressure difference is slightly better than the target pressure difference at medium and low speed. Accordinly, the engine performance and EGR level can meet the requirements of engine manufacturer.