Characteristic Analysis Of Inter Flow Field And Structure Design Of Brush Seal

Brush seal is a kind of flexible contact dynamic seal with low leakage rate,little wear and long life.Because of its excellent sealing performance,brush seal is widely applied in turbomachines such as aircraft engines,gas turbines and compressors.Brush seal technology has become the necessary method to improve the performance of turbomachinery.With the increasingly severe requirements on working environment of aero engine,the tightness of brush seal has to be tested.Therefore,it is pretty necessary to establish a numerical model that accords with the actual structure of the brush seal and study the characteristics of its internal media flow field,which has important research significance and engineering value on improving the tightness of brush seal.The tube bundle model consistent with the actual situation of brush seal as well as simplified two-dimensional and three-dimensional staggered tube bundle model should be established according to the characteristics of brush seal structure and working conditions,which is the key to analyze the media flow and study sealing mechanism of brush seal.The author built two-dimensional tube bundle model of the section of the brush,and used a software named Fluent to calculate based on the SIMPLE algorithm.The results of simulation results have been proved consistent with the experimental results of Bayley&Long rotor surface pressure,which proved the accuracy of the calculation model.On the basis of mesh independent judgment method,the author analyzed the grid independence of this model with airflow velocity,pressure drop and gas leakage rate of the relative change rate as reference quantity of grid independence test,and obtained the number of grid independence of computational accuracy,and then analyzed the relationship between the position of row spacing vortex point,pressure and brush distance as well as studied the influence of differential pressure between upstream and downstream and the distance of brush filaments on sealing property.The author also built three-dimensional tube bundle model of the section of brush,and used two software called Workbench and Fluent to calculate.The data obtained by numerical simulation are generally accordance with the pressure of rotor surface measured by Mike et al through which the accuracy of calculation model has been verified.The reliability of two-dimensional and the three-dimensional staggered tube bundle model is verified by comparison.The author studied the influence of pressure difference between upstream and downstream and backplane axial clearance on sealing property.Based on theoretical analysis in the third chapter and simulation conclusion in the fourth chapter,the author put forward four new types of brush seals structure and patented by combining brush seal with other types of seals and improving the structure of brush seal.The first is composite seal of labyrinth seal and shoe lining brush seal;the second one is composite seal of non-contact finger seal and shoe lining brush seal;the third one is combined low hysteresis brush seal with adjustable contact clearance;the last one is stitched brush seal of equal circumference.