小积液情况下卧式转子的稳定性实验研究

Experiment on Instability of Horizontal Rotor System Partially Filled with Small Amounts of Fluid

关键词:  燃机转子系统  失稳振动  小积液量  失稳边界转速  失稳边界积液量

Key words:  Gas turbine rotor system  Unstable vibrations  Small amounts of fluid-filled  Threshold speed of instability  Threshold amount of liquid for the unstable vibrations

摘要:

盘腔积液现象在舰用燃气轮机工作过程中时有发生，汽化的滑油和水蒸汽凝结形成积液。转子带动腔内的积液旋转，引发振动失稳，严重时会对发动机结构造成致命性破坏。为此，开展燃气轮机压气机盘腔积液的模拟实验研究，以双盘双支承的卧式柔性转子系统作为研究对象，重点关注小积液量的特点，对积液转子的动力学稳定性进行了研究。观测到转子的失稳现象，开展了不同积液体积、不同积液类型（水、植物油和滑油）等因素的影响规律研究，揭示了小积液的卧式转子动力学特征。研究结果表明：（1）对于积液失稳振动，存在失稳边界积液量，当积液量大于该边界值时，失稳将会发生。（2）失稳边界转速及恢复转速均高于临界转速。当转速高于失稳边界转速时，失稳将会发生。转速进一步增加，高于恢复转速时，失稳现象可能消失。（3）失稳时的振动特征为：出现幅值突增，次谐波成分也随之增加；基频和次谐波发生调制，表现出拍振特征。（4）随着积液体积的增加，失稳边界转速先减小后增加。（5）随着积液粘度系数增大，失稳边界转速和边界积液量均增大。

Abstract:

The rotor disk cavities of Marine gas turbine often cause self-excited vibrations due to fluid accumulation. The accumulated fluid forms by condensation of vaporized lubricating oil or water vapor. The rotor drives the liquid in the cavity to rotate， causing vibration instabilities. In this study， a horizontal flexible rotor system with two disks and two supports was examined experimentally. The rotor instability and stability restoration were observed， and the effects of the liquid volume and viscosity were studied to reveal the dynamic behaviors of small amounts of liquid in horizontal rotors. There was a threshold amount of liquid for the unstable vibrations， and instability occurred when the amount of fluid exceeded the threshold. A threshold speed of instability and recovery speed were found， both of which were higher than the critical speed. When the speed was higher than the threshold speed of instability， instability occurred. When the speed increased further， for speeds faster than the recovery speed， the instability disappeared. The amplitude of the total vibration increased suddenly， as did the sub-harmonic frequency. The fundamental and sub-harmonic frequencies were modulated and showed beat vibration characteristics. The threshold speed of instability decreased first and subsequently increased with the increase in fluid volume. With the increase in the viscosity coefficient of the fluid， the threshold speed of the fluid-filled rotor and amount of fluid increased. For unstable vibrations， the rate of amplitude growth increased rapidly.