大型离心压缩机闭式叶轮动力特性分析

通过模态分析与尾流激振响应分析,研究了离心压缩机闭式叶轮的动力特性与共振条件.针对尾流激振问题,基于气动计算建立激振力简化模型,提出了考虑激振力相位差的谐响应分析方法,计算出尾流激振产生的动应力水平与动力放大系数;基于IIW焊接疲劳标准计算了叶轮的结构热点应力.数值分析结果表明,在一定转速下,尾流激振产生的应力范围超过截止极限的50%,验证了三重点共振条件有效性的同时,指出了其局限性.

Analyses of dynamic characteristics of enclosed impeller of large centrifugal compressor

Through modal analysis and wake excitation response analysis,the dynamic characteristics and resonance conditions of the enclosed impeller of a centrifugal compressor are studied.For wake excitation problem,excitation force simplified model is established based on aerodynamic calculation,and the harmonic response analysis method is given based on the harmonic analysis method considering exciting force phase difference.The dynamic stress and dynamic amplification factor generating from wake excitation are computed.Based on IIW weld fatigue standard,the structural hot-spot stress of the impeller is calculated.The numerical simulation results show that the maximum stress produced by wake excitation may contribute more than 50% to the cut-off limit when the impeller rotates under a certain speed.The resonance conditions of triple point are validated,and its limitation is pointed out at the same time.