Research And Optimization Design Of Floating Ring Sealing Performance In Aeroengine Bearing Cavity

The excellent sealing performance of aero-engine bearing cavity is very important to the working efficiency,reliability,energy consumption and operating cost of aero-engine.In the rotary mechanical seal,the radial non-connection seal has good sealing performance and can reduce wear.With the development of rotating machinery in the direction of high speed,high efficiency and high power,and under high temperature and high pressure environment,the floating ring seal has smaller clearance,self-allocating function and better comprehensive performance compared with other traditional sealing structures,and has been widely used.The object studied in this paper is the floating ring mounted in the bearing cavity of the aero-engine.The seal form belongs to the floating non-contact seal.The inner diameter of the floating ring and the outer diameter of the rotating shaft form the dynamic pressure main sealing surface.Firstly,the inner diameter deformation and seal clearance variation of the inset floating ring under steady condition were analyzed under the action of thermal structure coupling.Then,the seal performance of the inset floating ring was analyzed by theoretical numerical calculation and simulation calculation.Finally,the seal test was carried out on the aero-engine seal bench.Finally,a circumferential groove was set on the inner diameter surface of the inlaid floating ring and the groove shape was optimized by using the optimization algorithm to obtain better performance of the floating ring.The main work of this paper is as follows:(1)According to the set of floating ring structure characteristics,to establish the two-dimensional axisymmetric finite element simulation model of research and analysis in the actual working conditions of convection heat transfer coefficient and heat flux density,the force applied load,boundary conditions were determined,and then analysis in Abaqus software set with floating ring in direct coupling thermal structure under the action of the distribution of temperature and thermal deformation,emphatically analyzes the deformation on the surface of the floating ring diameter,the changing rule of the seal clearance is obtained indirectly,prevent set with floating ring and the axis of rotation friction and make the seal system failure.(2)Based on the lubrication theory of sliding bearings,the mathematical model of the clearance flow field of the seal with inlaid floating ring was established.The dimensionless Reynolds equation of the seal flow field in turbulent state was converted into a difference equation by using the difference method,and the pressure distribution of the hydraulic oil film was obtained by using the over-relaxation iterative method.Through force analysis and oil film pressure distribution,the sealing performance parameters of the inlaid floating ring under steady condition are obtained,which provides a theoretical basis for the study of the sealing performance of the inlaid floating ring.(3)The three-dimensional model of the hydraulic oil film at the sealing gap of the inset floating ring was built by the Fluent simulation software.The appropriate fluid model and solution method were selected to simulate and calculate the leakage amount of the inset floating ring under the unbiased mental state.The leakage of floating rings with different eccentricity rates was calculated by numerical and simulation methods,and the results were compared and analyzed.Finally,bench test is carried out to verify the accuracy of numerical and simulation calculation of floating ring leakage.(4)Through set up floating ring diameter to the rectangular groove surface opening week,floating ring performance before and after study slot,the rectangular groove the influence of various parameters on the floating ring,through multi-objective genetic algorithm for rectangular groove parameter for structural optimization design,in guarantee under the premise of floating ring seal performance meet the requirements,reduce the inner diameter surface temperature and deformation of the floating ring,improve the stability of the sealing system.