Simulation Analysis Of Canted Coil Spring For Sealing Structure And Air Tightness Test

With the research and development of aircraft,high-speed aircraft and space shuttle aircraft had been developed rapidly.In the process of high-speed flight or re-entry,the air around these aircrafts will have severe aerodynamic load on the fuselage,forming high-temperature and high-pressure hot air flow around the fuselage.Once the hot air flow enters into some low-temperature parts through the gap,it will cause serious security risks to the safety of the aircrafts.Therefore,the sealing of these gaps is particularly critical,It has become one of the bottlenecks restricting the development of aircraft.In this thesis,the basic structure of the baseline sealing structure is as follows:1:The outer layer of quartz fiber braided sheath,which is mainly affected by its thermal resistance and flow resistance;2:The canted coil spring in the middle layer mainly provides rebound performance for the structure to meet the requirements of dynamic seal;3:The inner layer is filled with quartz fiber cotton,which mainly plays the role of thermal resistance and heat insulation.The main content of the research is the simulation analysis of the deformation behavior and resilience of the slant coil spring for the baseline sealing structure,which provides the design idea and theoretical basis for the preparation of the slant coil spring that meets the conditions;The baseline sealing structure was prepared,and the effects of different pressure difference,compression ratio and braiding form on its air tightness were discussed through experimental tests.As the resilient component of the baseline sealing structure,the canted coil spring is made of Inconel X-750 age strengthened Ni based alloy,which provides the resilience for the baseline sealing structure to compensate for the gap change,which is an important factor affecting the dynamic sealing performance.In this thesis,the parametric modeling of the canted coil spring is carried out through the parametric equation,and then the structural static simulation of the inclined coil spring is carried out based on the ANSYS finite element analysis software.The deformation behavior and resilience of the canted coil spring are studied,and the influence of the structural parameters of the canted coil spring on the resilience of the canted coil spring is discussed.Through the comparison between the results of finite element simulation analysis and the results of room temperature test,the curve of resilience compression is basically the same,which proves that the finite element simulation analysis is reliable.The simulation results show that when the height h,width W and inclination C of the canted coil spring are increased,the resilience of the inclined coil spring decreases;With the increase of pitch P and diameter D,the rebound force increases,and the relationship between diameter D and rebound force is high-order nonlinear;The temperature affects the young’s modulus of Inconel X-750 and the spring return force.When studying the air tightness model of the baseline sealing structure,it is found that there are two main ways for the gas leakage of the baseline sealing structure in service,one is to pass through the thickness direction of the sealing part to produce leakage,the other is that the high-temperature hot gas flows around the sealing part to produce leakage at the position where the high-temperature sealing part contacts with the sealing surface,which provides an idea for studying the air tightness of the sealing part.The experimental results show that the leakage of baseline sealing structure increases with the increase of pressure difference;it decreases with the increase of compression;The different braided form of the sheath is also an important factor affecting the air tightness of the baseline sealing structure.Through the experimental test,the 2.5D braided form of the sheath has better air tightness than the 2D braided form.