闭式叶轮变形对离心压缩机性能及气动载荷的影响

Influence of closed impeller deformation on the performance and the aerodynamic load of centrifugal compressor

为分析离心压缩机叶轮变形对其气动性能及气动载荷的影响,基于Workbench平台,以某离心压缩机首级闭式叶轮为研究对象,结合轮盖、级间间隙对叶轮进行流固耦合数值研究。以未发生变形的叶轮为对象,通过CFX计算压缩机内部流场,获取叶轮所受的压力场与温度场,结合离心力条件,对叶轮进行静力学结构分析从而获取叶轮多条件下的变形数据,并计算变形后的叶轮流场,对比分析叶轮在变形前后压缩机性能及叶片表面气动载荷变化规律。结果表明:静力学结构分析中,离心力是叶轮变形的主导因素;叶轮变形导致轮盖间隙减小,泄漏损失降低,压缩机总体气动性能略有提高,效率提高约1.4%。通过非定常计算获取叶表气动载荷,发现叶片前缘与尾缘气动载荷频率主要以转频为主;前缘气动载荷在叶轮变形导致的气流角与轮盖间隙泄漏流变化的共同影响下,平均气动载荷提升21.5%,尾缘由于叶轮膨胀变形与间隙流变化导致该处平均气动载荷提升62.4%。

In order to analyze the influence of centrifugal compressor impeller deformation on its aerodynamic performance and aerodynamic load, based on Workbench platform, and taking the first stage closed impeller of a centrifugal compressor as the research object, combined with wheel cover and interstage clearance, the fluid structure coupling numerical study of the impeller was carried out. Taking the undeformed impeller as the object, the internal flow field of the compressor was calculated by CFX to obtain the pressure field and temperature field of the impeller. Combined with the centrifugal force condition, the static structure of the impeller was analyzed to obtain the deformation data of the impeller under multiple conditions, calculate the blade rotation field after deformation, and compare and analyze the compressor performance and the variation law of aerodynamic load on the blade surface before and after deformation. The results show that centrifugal force is the dominant factor of impeller deformation in static structure analysis. The deformation of the impeller leads to the reduction of the clearance between the wheel cover and the leakage loss. The overall aerodynamic performance of the compressor is slightly improved and the efficiency is increased by about 1.4%. The aerodynamic load on the blade surface is obtained by unsteady calculation. It is found that the frequency of aerodynamic load on the leading edge and trailing edge of the blade is mainly rotation frequency. Under the joint influence of the air flow angle caused by the deformation of the impeller and the leakage flow change in the gap between the wheel cover, the average aerodynamic load at the leading edge increases by 21.5%, and the average aerodynamic load at the trailing edge increases by 62.4% due to the expansion deformation of the impeller and the change of the gap flow.