非对称端壁造型对离心压气机性能的影响

非对称端壁造型应用在轴流压气机和涡轮中具有较好的提高效率的作用。为了探究非对称端壁造型对离心压气机性能的影响,借鉴非对称端壁造型在轴流压气机中的设计经验,借助Autoblade和CFX商用软件,设计了四种非对称端壁造型结构,并对带叶片式扩压器的离心压气机展开数值计算研究。研究发现,与原型压气机相比,采用压力面附近为凸曲率形状、吸力面附近为凹曲率形状的非对称端壁造型结构PEW1_10%(profiled end wall 1_10%)可以在保证全工况效率不降低的情况下,使离心压气机的性能曲线向小流量和大流量均有拓展,稳定工作范围扩大11.8%。通过分析流场发现,在近喘振工况,非对称端壁造型PEW1_10%使扩压器通道内流量重新分配,吸力面附近径向速度增大,低能流体减少,改善了扩压器通道的流动状况,进而推迟喘振的发生。

Effects of Non-Axisymmetric Profiled End Wall Treatments on Performance of a Centrifugal Compressor

The application of non-axisymmetric endwall profiling on both axial compressors or turbines has been determined to be an effective way to increase the efficiency. In order to investigate the impact of non-axisymmetric end wall profiling on the performance of centrifugal compressors, four endwall contouring schemes according to the design experience of non-axisymmetric endwall profiling in axial compressors were performed on a vaned diffuser centrifugal compressor with the help of Autoblade and CFX software. The results showed that non-axisymmetric profiled endwall PEW1_10% which was convex near the pressure side and concave near the suction side extended the compressor characteristic performance curve to smaller and higher mass flow rate points which gave a 11.8% improvement of the operating range with no reduction of the efficiency compared with the original compressor. Analysis of the flow field showed that PEW1_10% caused a redistribution of the flux in the diffuser passage at the near surge condition, which further led to an increase of the radial velocity near the suction side and a decrease of the low-energy fluid. As a result, the flow condition in the diffuser passage was improved, and the surge was delayed.