碰摩双转子系统弯扭耦合振动分析与实验

针对航空发动机双转子系统,利用拉格朗日方程建立了含碰摩力的弯扭耦合动力学方程,采用龙格-库塔法进行数值计算,结合瀑布图、频谱图、分岔图、庞加莱截面图、幅频曲线分析了弯曲振动和扭转振动的频谱特征和分岔特性;利用增量式编码器对转子实验台进行了扭转振动测量,验证了数值计算得到的频率特征。研究结果表明:弯扭振动具有相似的特征频率,包括倍频、分数倍频、工作频率与倍频/分数倍频的组合频率,但扭转振动的特征频率更加明显;两者还具有相似的分岔过程和相同的分岔点,在每个分岔点处都存在幅值跳跃现象。 

Analysis and experiment of coupled bending and torsional vibration of a rub-impact dual-rotor system

For a dual-rotor system of aero-engine, the coupled bending and torsional dynamic equations with rub-impact force were first established using the Lagrange equation. The Runge-Kutta method was used for numerical calculation. Combined with waterfall map, spectrum diagram, bifurcation diagram, Poincaré map and amplitude-frequency curve, the spectral characteristics and bifurcation characteristics of the bending vibration and torsional vibration were analyzed. The torsional vibration of the rotor experimental platform was measured by incremental encoders to verify the spectral characteristics obtained from the simulation analysis. The research results show that the torsional vibration exhibits characteristic frequencies similar to bending vibration, including multiple frequency, fractional frequency, and the combined frequency of working frequency and multiple/fractional frequency, but these are more obvious in the torsional vibrations; bending and torsional vibrations have similar bifurcation process and same bifurcation point, and there are jump phenomena of amplitude at each bifurcation point.