Numerical Calculation And Structural Optimization Method For Leakage And Heat Transfer Characteristics Of Brush Seal

Brush seal is a new type seal structure which is used to overcome the lack of labyrinth seal.It is composed of brush bundle,front cover plate,aft cover plate and rotating shaft.The brush bundle contains metal material with high flexibility and ductility,which allows deformation and runout of the rotating shaft in the radial direction.Compared with the labyrinth seal,it has a certain research value with less wear and lower leakage.At present,there are still many problems in the study of leakage and heat transfer of brush seal,especially in the numerical calculation of leakage and heat transfer under the condition of brush wear,and in the optimization of structural parameters.In view of the shortcomings of leakage,heat transfer and optimization of brush seal,the porous media model and optimization model were established in this paper to carry out the research of brush seal.First of all,according to the flow state of the fluid in the brush bundle,a porous media model of leakage and heat transfer considering wear was established.Combined with the structural characteristics of the brush seal and the change of the brush wire in the wear process,the interference amount considering wear was determined,and the key parameters in the model were determined one by one.Secondly,the numerical simulation calculation of leakage and heat transfer of brush seal is carried out,and the flow distribution of leakage gas in the calculation domain under different working conditions is analyzed,as well as the change rule of gas leakage and maximum temperature with time under different structure and working parameters.Finally,considering that the seal quality of brush seal is restricted by leakage and heat transfer,this paper proposes a structure optimization method of brush seal based on approximate model.In the process of optimization,the optimization objective,optimization variables and constraint conditions were determined according to the design requirements of the brush seal,and the optimization model of the brush seal was established based on the selection of the optimization objective,optimization variables and constraint conditions.Secondly,based on the orthogonal experiment method in the experimental design method,the orthogonal table was designed to determine the initial sample points,and the approximate model was constructed to establish the relationship between the optimization variables and the optimization target,and the accuracy of the approximate model was verified.If the accuracy of the approximate model met the requirements,the appropriate optimization algorithm was selected to optimize the approximate model.Thus,a set of structural parameters of brush seal satisfying the optimization objective are obtained.On the contrary,the approximate model needs to be reconstructed.The results show that the dramatic change of leakage pressure mainly occurs in the part of the brush bundle.The closer the distance to the surface of the rotating shaft,the more obvious the change of radial and axial pressure in the part of the brush bundle is.At the initial stage of wear,the leakage increases gradually with time,and changes slowly with time increasing,and finally tends to be stable.The maximum temperature at the initial stage of wear decreases gradually with time,and eventually tends to be stable with the increase of time.