火箭发动机液氢涡轮泵转子-密封系统的非线性动力稳定性

研究了不平衡激励下密封对火箭发动机液氢涡轮泵转子系统非线性动力稳定性的影响；采用Muszynska模型描述密封流体激振力，根据Timoshenko梁-轴有限元模型离散化转轴，建立了实际液氢涡轮泵转子-密封系统的非线性有限元模型；结合Floquet理论和打靶法，分析了该不平衡系统的动力稳定性和非线性行为。研究表明：密封诱发的次同步进动造成的系统失稳破坏首先发生在涡轮端轴承；轴承阻尼、密封轴向雷诺数和密封长度对系统临界失稳转速有显著影响，随着轴承阻尼和密封轴向雷诺数的增大，系统临界失稳转速增加，随着密封长度的增加，临界失稳转速逐渐变小。

Nonlinear Dynamic Stability of Liquid Hydrogen Turbopump Rotor-Seal System in Rocket Engine

The effect of seal on the nonlinear dynamic stability of liquid hydrogen turbopump rotor system in rocket engine was investigated. The liquid dynamic forces due to seals were described by Muszynska model, and then the nonlinear finite element model of an actual liquid hydrogen turbopump rotor-seal system was established. Associated with the shooting method and Floquet theory, the dynamic stability and nonlinear phenomena of this unbalanced rotor-seal system were analyzed. The results indicate that the system damage caused by the subsynchronous whirl motion due to seal liquid forces first occurs at the turbine end bearing. The bearing damping, axial Reynolds number and seal length exert significant effects on the stabilization of the turbopump rotor-seal system. The onset speed of instability decreases with seal length and increases as the bearing damping and axial Reynolds numbers rise.