袋型阻尼密封动力特性分析及对转子稳定性的影响

Analysis of the Rotordynamic Characteristics of Pocket Damper Seals and Impact on Rotor Stability

密封动力特性对透平机械转子系统稳定性影响较大。文中应用非定常动网格技术建立了考虑转子涡动的袋型阻尼密封动力特性求解模型,在验证求解模型准确性的基础上,比较分析了转子涡动频率、涡动振幅对传统迷宫密封和袋型阻尼密封动力特性的影响,基于密封气动功方法定量分析了袋型阻尼密封的抑振机理。研究结果表明：与传统迷宫密封相比,袋型阻尼密封的周向隔板降低了密封腔内气流的周向速度,其泄漏特性与传统迷宫密封相当;在所研究的工况下,袋型阻尼密封指向转子涡动中心的径向气流力以及与转子涡动速度方向相反的切向气流力均大于传统迷宫密封,有效地降低了转子涡动振幅和涡动速度;与传统迷宫密封相比,转子涡动频率和涡动振幅越大,袋型阻尼密封气动功的绝对值越大,抑振效果越好。

The rotordynamic coefficients of seals are important parameters to evaluate the stability of rotor system in turbomachinery. A rotordynamic characteristics solution model of pocket damper seals considering whirl motion of the rotor using unsteady solution combined with mesh deformation technique was established. On the basis of verifying the accuracy of the solution model, comparative analysis of the whirl frequency and whirl amplitudes of the rotor influence on the rotordynamic characteristics of traditional labyrinth seals and pocket damper seals, and study the suppression vibration mechanism of pocket damper seals based on aerodynamic work. Study results show that： compared with traditional labyrinth seals, pocket damper seals reduce circumferential airflow velocity in seal cavity, and the leakage characteristic of pocket damper seals with almost equal to that of traditional labyrinth seals. In the present operating conditions range, pocket damper seals have a large radial airflow force pointing to the rotor whirl orbit center and a large tangential airflow force opposite to the rotor whirl velocity, so pocket damper seals effectively reduce rotor whirl amplitudes and whirl velocity. The larger whirl frequency and whirl amplitudes of the rotor, the greater the absolute value of aerodynamic work, and good suppression vibration effect of pocket damper seals.