考虑热效应影响的指尖密封接触强度分析

指尖密封作为柔性高速动态密封装置,其在航空发动机、燃气轮机等重大设备的高速密封部位具有良好的应用前景。但高速高温条件下,摩擦生热和环境温度对指尖密封配副接触强度具有重要影响,进而影响其密封性能,探索其影响机理成为指尖密封性能设计中的关键。为此,研究针对指尖密封实际工况条件,将摩擦生热转化为热流密度边界条件,同时计入密封介质温度的影响,构建了指尖密封系统的热结构耦合分析模型,研究了热效应对指尖密封/转子配副接触强度的影响规律,并进行了物理试验验证。研究结果表明,高速条件下摩擦生热对密封配副接触强度具有重要影响,转速为15 000 r/min时,室温条件下,摩擦效应导致指尖密封局部温度升高超过370℃,指尖靴/转子摩擦配副间接触压力增大近10%;高温条件下,考虑热效应影响后,导致局部接触压力相对于不考虑热效应影响时减小了90%;性能试验结果表明考虑热效应后,密封上下游压力差为0.4 MPa时,指尖密封泄漏试验结果的最大误差仅为16.5%,而不考虑热效应影响时,最大误差达到了72.8%,验证了考虑热效应的必要性和热分析方法的合理性,为高温、高速条件下的指尖密封性能设计提供了重要参考。

CONTACT STRENGTH ANALYSIS OF FINGER SEAL CONSIDERING THERMAL EFFECT

As a flexible high-speed dynamic sealing device,the finger seal has a good application prospect in high-speed sealing parts of aircraft engines and gas turbines. However,Under high-speed and high temperature conditions, friction heat and ambient temperature have a significant impact on contact strength and sealing performance of the finger seal. So exploring its influence mechanism becomes the key problem of finger seal design. Therefore,based on the actual working conditions,converting the friction heat to the heat flux density boundary condition,considering working temperature,a coupled thermal structural analysis model of the finger seal system is built,and the influence of thermal effect on the contact strength of the finger seal/rotor pair is studied,then it verified by tests. The results show that friction heat has an important influence on the contact strength of the sealing pair at high speed. Under normal temperature conditions,the local temperature of the finger seal rises above 370℃ because of friction effect,and the contact pressure at finger foot/rotor friction pair increases by nearly 10%. Under high temperature conditions,when the thermal effects are considered,local contact pressure is reduced by 90%. The performance test results show that,the maximum error between theoretical and test result is only 16.5% under pressure of 0.4 MPa,while the maximum error reaches 72.8% when thermal effect is not considered,which verified the necessity of thermal effect and the rationality of thermal analysis method. So the study provides an important reference for the design of finger seal under high temperature and high speed conditions.