偏心密封动力特性分析与新型自同心密封研究

Dynamical Characteristics of Eccentric Seal and Novel Floating Self-Adapt Concentric Seal Concepts

关键词:  密封  动力特性  多频椭圆涡动  偏心率  浮动式自同心密封

Key words:  Seal  Dynamical characteristics  Multiple frequencies elliptical whirling  Eccentricity ratio  Floating self-adapt concentric seal

摘要:

密封气流激振引起的转子失稳已成为发展高性能透平机械的瓶颈问题。为了研究偏心率对密封动力特性及转子稳定性的影响规律，揭示转子偏心诱发密封气流激振的机理，采用非定常动网格技术方法，建立了多频椭圆涡动轨迹的密封动力特性求解模型。在此基础上，提出了新型浮动式自同心密封结构，包含密封环浮动式和密封环自适应同心两大理念，分析了新型密封的工作原理以及力学特性。结果表明:密封的等效刚度和等效阻尼随着偏心率的增大而减小。不同涡动频率下，当偏心率增加到0.7时，等效阻尼相比于同心密封下降幅度达到33%～76%。随着偏心率的增大，密封气流力对转子做功增加，降低了转子系统稳定性；随着偏心率的增加，密封流体动压效应增强，密封气流激振力增大，转子系统稳定性降低，偏心转子密封流体动压效应是产生密封气流激振的主要原因；新型浮动式自同心密封的工作原理及动力学特性分析结果表明，新型密封具有自适应同心功能。

Abstract:

The instability of rotor caused by the aerodynamic loading has become the bottleneck problem for the high performance turbomachines. In order to study the effects of the eccentricity ratio on dynamics characteristics and rotor stability of the labyrinth seal， and reveal the mechanism of aerodynamic loading in rotor eccentric， multiple frequencies elliptical whirling solution model was established by using unsteady transient solution combined with mesh deformation of dynamical characteristics for seal. On this basis， a new type of floating self-adaption concentric seal structure was proposed， which included two concepts of floating seal ring and self-adaption concentric seal ring， the working principle and dynamic characteristics of novel seal are analyzed. Study results show that equivalent stiffness and equivalent damping decrease with the increase of the eccentricity. When the eccentricity increases to 0.7， the equivalent damping decreases by 33% ～ 76% compared to concentric seal at different whirling frequencies. The aerodynamic work is related to the eccentricity increase and increase， which reduce the stability of the rotor system. The hydrodynamic action enhances with the increase of eccentricity， the stability of the rotor system decreases due to the air induced vibration force increasing for seal， the main reason of the aerodynamic loading is the hydrodynamic action in eccentric rotor. The working principle and dynamic characteristics of novel floating self-adaption concentric seal also show that novel floating self-adaption concentric seal has certain feasibility.