凹槽射流对袋型阻尼密封泄漏特性与动力特性影响机理

采用非定常动网格技术建立了袋型阻尼密封泄漏特性和动力特性多频椭圆涡动求解模型，在验证求解模型准确性的基础上，研究了压比、转速和凹槽位置不同时凹槽射流对袋型阻尼密封泄漏特性与动力特性的影响，分析了袋型阻尼密封轴向与周向的流速和压力分布特性，揭示了凹槽射流对袋型阻尼密封泄漏特性和动力特性的影响机理。研究表明:凹槽射流增强了袋型阻尼密封直通效应，削弱了基本腔室内气流动能的耗散作用，增大了泄漏量，当压比由2增至6.9时，相比无凹槽袋型阻尼密封，有凹槽袋型阻尼密封泄漏量增大11.75%~12.67%。凹槽射流可减小袋型阻尼密封交叉刚度，增大直接阻尼和有效阻尼，且转子低频（频率小于120 Hz）涡动时效果更显著；凹槽射流可抑制下游腔室内气流的周向流动，降低周向压差，使周向压力分布更均匀，提高转子稳定性；凹槽结构参数相同时，基本腔室出口密封齿周向二等分点为最佳凹槽位置，此时袋型阻尼密封具有最小交叉刚度、最大直接阻尼和有效阻尼。 

Mechanism of influence of notch jet-flow on leakage and rotordynamic characteristics of pocket damper seals

The unsteady dynamic mesh method was used to establish a multi-frequency elliptical whirl solving model to obtain the leakage and dynamic characteristics of pocket damper seals；based on the accuracy of the numerical model，the influences of different pressure ratio，rotor speed and notch position on leakage characteristics and the dynamic characteristics were studied，the speed and pressure distribution characteristics of different conditions and the notch position were analyzed，so the influence mechanism of notch jet-flow on leakage and dynamic characteristics of the pocket damper seals was revealed.The results showed that: notch jet-flow enhanced the straight-through effect of pocket damper seals，weakened the dissipation of air kinetic energy in the basic chamber，and increased the leakage.When the pressure ratio increased from 2 to 6.9，the leakage increased by 11.75%-12.67%.The notch jet-flow can reduce the cross stiffness of pocket damper seals，increase the direct damping and effective damping，and the effect was more significant when the rotor swirled at low frequency （frequency was less than 120 Hz）; the notch jet-flow can restrain the circumferential flow of the airflow in the downstream chamber，reduce the circumferential pressure difference，reduce the exciting force and improve the stability of the rotor.When the structural parameters of the notch were same，the circumferential second-order dividing point of the seal tooth at the outlet of the basic chamber was the best notch position.At this time，pocket damper seals had the minimum cross stiffness and the largest direct damping and effective damping.