基于气动激励特征的压气机叶片高周疲劳分析

High cycle fatigue analysis of compressor blade based on aerodynamic excitation characteristics

针对动静干涉条件下压气机叶片在离心载荷与气动载荷耦合作用下的疲劳强度问题,本文开展了最高效率和近失速工况下叶片表面非定常气动激励的时域和频域特征研究,提出了气动激励引发叶片耦合振动的疲劳寿命预测方法。结果表明:非定常气动激励引起叶片一阶耦合振动和近失速时多阶高倍频诱导叶片在工作转速裕度内产生高阶谐振。近失速时比最高效率点应力增加2.3%,疲劳寿命降低11.1%,易造成叶片前缘叶根疲劳断裂。研究结果表明:工程设计应采用双向流固耦合方法进行叶片强度校核,以提高压气机的安全性和可靠性。

For the problem of fatigue strength of compressor blades under the coupling of centrifugal and aerodynamic loads and the condition of rotor-stator interaction,we studied the time domain and frequency domain characteristics of unsteady aerodynamic excitation on blades under the highest efficiency and near-stall conditions and proposed the fatigue life prediction method for aerodynamic excitation inducing blade-coupling vibration.The results show that the first-order coupled vibration of blades induced by unsteady aerodynamic excitation and the high-order resonance induced by multi-order high-frequency doubling near stall lead to the high-order resonance of the blades within the operating speed margin.The stress at near-stall conditions increases by 2.3%compared with that at the maximum efficiency point,and the fatigue life decreases by 11.1%,which easily causes fatigue fracture of the leadingedge blade root.The study demonstrated that the bidirectional fluid-structure coupling method should be used for blade strength assessment in engineering design to improve the safety and reliability of compressors.