失调叶片盘的振动机理

VIBRATION CHRACTERISTICS OF MISTUNED DISK-BLADED

本文对于失调叶片盘的耦合振动问题 ,采用子结构模态综合法建立系统的振动微分方程 ,利用试验模态分析及模态修正计算求得调谐叶片和外缘带锥壳轮盘的若干低阶模态。通过对叶片模态刚度的微量摄动 ,构造真实的失调叶片盘和各种理论分析失调模型。对某个实际的失调叶片盘的非旋转强迫振动试验验证了系统的力学模型和计算公式。计算结果分析表明 ,失调叶片盘强迫振动响应中个别叶片振动过甚乃为叶片失调所致。对各种失调模型的振动计算表明 ,小频差的随机失调优于其他失调分布形式。并就算例给出了最佳频差幅值和恰当的发动机工作频率范围。

A mathematical model by Substruture Mode Synthesis Methed is provided for coupling vibration of a mistuned disk bladed.Several low order modes of each substructure are obtained by means of Experimental Modal Analysis and modifying calculation of the modes.Relying on the small perturbation of blade modal stiffiness,real mistuned disk bladed and several kinds of theoretical mistuned models are set up.Model parameters and mathematical formalas are checked by use of forced vibration experiment of a real mistuned disk bladed on vibrostand.Analytical results well reveal that the mistuning of blades is the reason why resonant response of some blade on the same stage disk is much greater than other blades.The results also show that smaller frequency difference and random mistuning distribution of blades are eligible,and also give the rational range of rotating frequencies of an engine.