转子叶片气弹稳定性与强迫响应分析

Analysis of Aeroelastic Stability and Forced Response of Rotor Blades

针对由叶轮机械转子叶片流致振动引起的叶片高循环疲劳失效的突出问题,采用数值模拟方法对叶片流致振动特性进行预测分析。常见的流致振动问题包括气弹稳定性和强迫响应,分别以压气机和高压涡轮转子叶片为例给出了气弹稳定性和强迫振动响应的分析方法及其流程。对于压气机叶片,采用能量法和特征值法进行了气弹稳定性计算。结果表明:气弹稳定性结果相互吻合,在高阶模态下的气动阻尼比在低阶模态下的更小,根据振型特征确定危险点位于叶尖近前缘和近尾缘部位,在该部位可能导致叶片掉角, 对于高压涡轮叶片,分析了其强迫振动响应特征。结果表明:叶片非定常气动激励主要来源于上游导叶,在设计状态下其频率距离转子叶片第5阶模态频率较近,并对危险模态阶次的共振应力进行分析,在0.14%阻尼下振动应力最大可达134 MPa。

Aiming at the prominent problem of high cycle fatigue failure of blade caused by flow-induced vibration of turbomachinery blade,numerical simulation method was used to predict and analyze the flow-induced vibration characteristics of blade.The common flowinduced vibration problems include aeroelastic stability and forced vibration response.Taking compressor and high-pressure turbine blades as examples,the analysis methods and processes of aeroelastic stability and forced vibration response were given.For the compressor blade,the energy method and the Eigenvalue method were used to calculate the aeroelastic stability.The results show that the aeroelastic stability results are consistent with each other,and the aerodynamic damping in the high-order mode is smaller than that in the low-order mode.According to the characteristics of the vibration mode,the dangerous point is located near the leading edge and trailing edge of the blade tip,which may cause the blade to crack at tip corners.For the high pressure turbine blade,the forced vibration response characteristics were analyzed.The results show that the unsteady aerodynamic excitation of blades is mainly from the upstream guide vane.The frequency is close to the fifth mode frequency of the rotor blade in the design state.The resonance stress of dangerous modal order is analyzed,and the maximum vibration stress can reach 134 MPa under 0.14%damping.