Research On The Characteristics Of Oil-gas Two-phase Carbon Fiber Brush Seal

Brush seal has been extensively applied to high-speed rotating machinery,such as aeroengine,on account of its superior performance.At present,the research on brush seal is generally limited to pure gas phase medium,and serious wear and short life are still the important problems of brush seal.In terms of the performance requirements of oil-gas twophase medium,low leakage,low wear,and long life of the high-speed bearing cavity seal,this paper designs the oil-gas two-phase large interference flexible carbon fiber brush seal.The sealing properties such as leakage and heat-transfer characteristics of the brush seal are analyzed combined with numerical calculation and experimental study.Based on the theory of porous media,the porosity and drag coefficient of bristle pack are derived,and the drag coefficients of the two bristle packs are obtained.The numerical model of leakage and heat-transfer characteristics of carbon fiber brush seal are established by using Fluent software,the Mixture oil-gas two-phase flow model was selected for calculation,which laid the foundation for the subsequent numerical analysis.The distribution of pressure,medium,flow velocity and temperature of the oil-gas two-phase carbon fiber brush seal are analyzed.The sealing mechanism,wear reduction characteristics and high heat transfer characteristics of the sealing device are explained.The influences of structure parameters and operation parameters on leakage rate,outlet oil-gas ratio,heat flow rate and heat-leakage ratio of oil-gas two-phase carbon fiber brush seal are analyzed,and the design suggestions for the value range of structural parameters are given.Based on the orthogonal experimental method,the effect of structural parameters on each single performance of oil-gas two-phase carbon fiber brush seal are analyzed,and the combination of structural parameters with the best comprehensive performance is obtained.A structural design optimization method focusing on each single performance and considering the comprehensive performance is obtained,which can directly guide the design of carbon fiber brush seal in practical engineering applications.The oil-gas two-phase carbon fiber brush seal test bed is designed and built,formed the carbon fiber brush seal laboratory processing technology,and processed different structures of the test pieces.Under various working conditions,contrast experiments of static leakage,dynamic leakage and friction heat generation using different structures carbon fiber brush seal are conducted.The influence of bristle and rotor material on the leakage and friction heat generation characteristics are analyzed,and some suggestions on the selection of bristle and rotor material are given.The structural feasibility and performance advantages of the carbon fiber brush seal,such as low leakage,low "hysteresis effect" and high stability,are proved,and the correctness of the numerical simulation is proved.Through the research on the leakage and heat-transfer characteristics of the oil-gas twophase carbon fiber brush seal,this thesis makes up for the lack of research on brush seal in oil-gas two-phase medium,lays a foundation for the theoretical research of non-metallic bristle brush seal and provides design guidance for engineering practice.