蜂窝密封泄漏特性理论与实验

蜂窝密封的泄漏特性直接影响航空发动机的工作效率。本文采用理论分析与实验研究相结合的方法系统研究蜂窝密封的泄漏特性。建立了蜂窝密封流场特性CFD求解模型,数值分析了转速、进出口压比、蜂窝孔对边距、蜂窝孔深、蜂窝壁厚等因素对密封泄漏量的影响,揭示了蜂窝密封的封严机理。设计搭建了蜂窝密封泄漏特性实验台,实验研究了进出口压比、转速等因素对蜂窝密封泄漏特性的影响。数值分析与实验测试相互验证,在此基础上,考虑蜂窝密封泄漏特性影响因素,结合传统经典迷宫密封泄漏量Egli公式,构造了蜂窝密封泄漏量计算公式。研究结果表明,蜂窝密封的孔深、对边距和壁厚是通过影响蜂窝孔中涡系的发展和蜂窝孔的密度来影响泄漏量的。涡系发展的越充分,蜂窝孔的密度越大,蜂窝密封的泄漏量就越小;转速对蜂窝密封泄漏量影响较小;蜂窝密封的泄漏量随进出口压比的增加而增大,两者近似呈线性关系;随着蜂窝孔深度增加,蜂窝密封泄漏量先逐渐减小后逐渐趋于平稳;随着蜂窝孔对边距增加,密封泄漏量先减小,后出现了小幅度的增加;随着蜂窝壁厚的增加,蜂窝密封泄漏量先近似线性增大后缓慢增大。本文研究为蜂窝密封结构设计提供理论依据。

Theoretical and experimental study of leakage characteristics of honeycomb seal

The leakage characteristics of the honeycomb seal directly influence the working efficiency of the aero-engine.The leakage characteristics of honeycomb seal are analyzed using theoretical and experimental methods.The CFD model for the flow characteristic of honeycomb seal is developed to analyze the influence of rotational speed,inlet/outlet pressure ratio,subtense distance,cell depth,and wall thickness on seal leakage and to reveal the densification mechanism of honeycomb seal.The seal leakage test rig is designed and built to analyze the influence of the inlet/outlet pressure ratio and the rotational speed on leakage of honeycomb seal.Numerical analysis and experimental tests are conducted to verify each other.Based on the Egli formula for leakage quantity of the traditional classic labyrinth seal,the calculation formula for the leakage quantity of honeycomb seal is constructed,considering the factors influencing the leakage characteristics of honeycomb seal.The results show that the cell depth,subtense distance and wall thickness can influence the development of the vortex system and the density of honeycomb holes,and thereby influence the leakage.The more fully the vortex system develops and the greater the density of honeycomb hole is,the less honeycomb seal leakage will be.The results show that the rotational speed has little influence on the honeycomb seal leakage.The leakage linearly increase with the increasing inlet/outlet pressure ratio.With the increase of the honeycomb cell depth,the honeycomb seal leakage is firstly reduced and is then stabilized.With the increase of the subtense distance,the honeycomb seal leakage decreases initially,and then increases in small particle size range.With the increase of the wall thickness,the honeycomb seal leakage increases linearly initially,and then slowly increases.The results of this study can assist in improving the design of annular seal.