An Investigation Of Characteristics Of Leakage,Heat Transfer And Hysteresis Of Brush Seal

Since the introduction of the brush seal,because of the superior sealing characteristic,it is an important way to reduce the loss of engine flow and significantly improve the performance of the engine.For the sealing technology,leakage characteristic has been the focus of research,with the further development of brush seal,the friction heating problem between the bristle tips and rotor as well as the hysteresis of bristle is the major limitations of brush seal application.Establishes the numerical model more appropriate to practical applications,investigations on the leakage characteristics,heat transfer characteristics and hysteresis characteristics of brush seal have significance to improve the brush seal performance.In the thesis,an anisotropic porous medium model of flow and heat transfer is established,the factors affecting the leakage and heat transfer characteristics are studied,using the orthogonal test formulate 32 numerical calculation schemes,the results is used to study the effects of outer diameter,inner diameter,bristle diameter,bristle lay angle,bristle back width,fence height and pressure drop,rotor speed,temperature on leakage and heat transfer characteristics of brush seals.Bases on the force analysis of bristles,the equivalent dynamic model of single bristle is established,the parameter average gap that take performance of hysteresis is put forward,the results is used to study the effects of bristle lay angle,bristle diameter,outer diameter,fence height and pressure drop of bristles on hysteresis of brush seal.Finally,the leakage and hysteresis characteristics of basic brush seal and low hysteresis brush seal are compared,the effects of the axial clearance on leakage of the low hysteresis brush seal is studied.The results show that:(1)With all structural parameters studied in the thesis,outer diameter and inner diameter have greatest influence on the leakage,bristle back width and bristle diameter take the second place;inner diameter,bristle diameter and outer diameter have greatest influence on the leakage,bristle lay angle and bristle back width take the second place,the results provides technical references for the geometry design of brush seals.(2)The friction between bristle and the back plate plays a important role in the hysteresis of brush seal,the average gap decreases with the bristle diameter and fence height increase,the hysteresis of brush seal is weakened;the average gap increases with bristle lay angle,outer diameter and pressure drop of bristle increase,the hysteresis of brush seal is enhanced.(3)The low hysteresis brush seal can effectively reduce the friction between bristle and the back plate,the hysteresis is improved obviously.But with the increases of the axial clearance,the leakage of the low hysteresis brush seal is obviously increased.