Research On The Characteristics Of The Labyrinth Seal With Nonuniform Distribution Cavity Length Uesed In The Liquid Oxygen Turbopump

The labyrinth seal is widely uesd in turbomachinery. Its excellent performance has been proven as an important part in increasing the rotational speed of the rotor. Current research on characteristics of the labyrinth seal has made abundant achievements in building leakage computational models and liquid exciting vibration models. However, current research is not enough because the exisitng leakage computational models and liquid exciting vibration models only can be used in specific conditions。As the rapid development of the computer technology, the Computational Fluid Dynamics(CFD) has been gradually developed to solve some kind sophisticated fluid problems occurs in the labyrinth seals. CFD-based methods have received increased attention because the use of CFD-based methods for seal analyses allows for a more general applicability in terms of both geometry and operating conditions and CFD-based methods use much fewer assumptions in the description of the seal flow physics, resulting in good precision. A popular CFD software FLUENT is used in this dissertation to analyze the flow field in the labyrinth seal to study the leakage characteristics and rotordynamic characteristics, The time-dependent methods with dynamic mesh is used to solve dynamic coefficients and a structure of labyrinth seal with nonuniform distribution cavit y length is proposed.The dissertation primarily builds the 3D flow field model of the labyrinth seal and gives detailed analysis on setting boundary conditions and mesh dividing. Secondly, the leakage characteristics of the labyrinth seal have been studied, and the influences of clearance, eccentricity, rorating speed and inlet pressure on the veloctity distribution, pressure distribution, force situation of the rotor and t he leakage have been discussed to for further understanding the mechanism of flow induced vibration., laying the foundation for the research of rotordynamic characteristics. Then the time-dependent methods with dynamic mesh is used to solve dynamic coefficients to obtain results about how clearance, eccentricity, rorating speed and inlet pressure influence the rotordynamic characteristics of the labyrinth seal. Finally, on the basis of previous studies, the influence of nonuniform distribution cavity length on the leakage characterisitcs and rotordynamic characteristics has been discussed and a structure of labyrinth seal with nonuniform distribution cavity length is proposed.