Analysis Of Response Characteristics For Circumferential Seal Structure Of Main Bearing Cavity

With the development of aero-engine technology,the performance requirements for the circumferential seal of the main bearing cavity are becoming higher and higher.To meet the requirements of sealing performance,it is necessary to have the ability to adapt to the large radial runout,angular deflection and axial traverse caused by the sealed runway.This paper takes a certain type of aerospace engine circumferential seal device as the research object,and uses the finite element analysis method to develop a circle that considers the radial runout,angular deflection,axial traverse and mutual interaction under single and multiple excitations.Analysis of vibration response characteristics of sealed systems.According to the analysis results,for the constrained springs that affect the response characteristics,the response characteristics of the sealing system under different spring stiffness under different excitations are considered and optimized.At the same time,the programming of analyzing the response of the sealing structure under different excitations is completed.The main research contents are:(1)Based on the position distribution of the aero-engine seal system,the main bearing cavity seal system model was extracted,the load analysis of the seal system was completed,and the corresponding load calculation formula was given.It mainly includes:establishment and analysis of mechanical analysis model of seal system,solution of radial load and axial load of seal system,and simplified model processing according to requirements.Through the simulation calculation of the model around the axis(rotation centerline or geometric axis),the unbalanced inertial forces under radial runout and angular deflection are obtained,and formulas for fitting calculations under different inertial forces are given.(2)A three-dimensional analysis model of the circumferential seal structure is established.The finite element analysis method is used to establish the finite element model required for dynamic analysis.The vibration response characteristics of the circumferential seal under single radial runout,single angular deflection and axial traverse are obtained.The results show that the maximum vibration peak value of the seal ring gradually increases with the increase of runout or deflection angle.The most likely failure position of the seal ring is located at the pin slot.The equivalent stress change trend and vibration at the pin slot The response curve is similar,and the seal ring may cause local damage under a large amount of runout.By comparing the vibration response under single and multiple vibration excitations,it is obtained that the maximum displacement of the seal ring is reduced under multiple excitations,but more wave peaks appear,and there is a large gap at the joint,so the main seal and joint become major leaks.Position,angular deflection will also produce axial displacement,resulting in leakage at the auxiliary seal.In the axial traverse vibration excitation,the relative angular deflection excitation is obtained.The axial traverse vibration has a small effect on the axial vibration displacement of the seal ring and a small effect on the sealing performance.The results show that radial runout and angular deflection are the main forms of excitation that affect the response of a sealed structure.(3)Based on the simulation analysis of radial runout,angular deflection and axial traverse,the response characteristics of the circumferential seal structure were determined.The results show that in the coupling of radial runout and angular deflection,the radial runout has a greater impact on the vibration of the seal structure.In the radial plane,the maximum displacement of the seal ring is reduced under multiple excitations,and the number of peaks increases.The clearance increases,and the main seals and joints become the main leaks.In the axial plane,odd number of excitation displacements show a decreasing trend,and even number of excitation displacements show an increasing trend.In the coupling of radial runout and axial traverse,angular deflection and axial traverse coupling,the axial direction of the seal ring changes greatly,and the radial vibration effect is not obvious.It is concluded that only single radial runout or single angular deflection is considered in the radial direction,ignoring the effects of axial traverse.In the three coupling effects of radial runout,angular deflection and axial traverse,the increase in the time and size of the gap at the main seal and the auxiliary seal is more obvious.The response process of the three coupled excitations has more changes,more peaks,and larger gaps.Compared with other forms of coupled excitation,it takes longer to restore stability and has a greater impact on the sealing performance of the sealing system.(4)Combined with the analysis of the response characteristics of the circumferential seal structure under different excitations,the seal structure is improved.By changing the stiffness of the radial spring or the axial spring,the vibration response of the sealing ring is analyzed,and it is obtained that changing the spring stiffness can reduce the leakage of the sealing system to a certain extent,and the stiffness is 2 to 3 times suitable.The second development of ANSYS is carried out by VC++ to realize the software of analysis.The research results of this paper provide a good foundation for the improvement of circumferential seal performance and design.