Research On Numerical Analysis And Optimization Of Mechanical Sealing Performance

Under heavy load, the local high temperature and high stress was produced on mechanical seal face, influenced the whole sealing performance seriously. Because the parameter on sealing performance was difficult to calculate accurately by traditional theory, so the system model of calculating mechanical sealing performance was needed urgently. Based on ANSYS software and combined with the theory trends on mechanical sealing performance, the systematic finite element model of analyzing sealing performance from three respects— static, stable and transient state had been set up in this paper, and the optimize studying was done further.In analyzing static structural mechanics, the deformation analysis was selected as initial object, the deficiency of calculating separately and analyzing wholly by gluing the mechanical seal face was analyzed. Based on contact theory, the method of integral analysis by using contact elements were put forward, guaranteeing the harmony of pressure and deformation, realizing the automatic solution of contact pressure on face and the balance of seal ring. The mechanics analysis result indicated that the taper-deformation was originated on the surface of seal rings under pressure and moment, formed the contact area and taper-opening area, and the pressure and stress is centralized in contact area.In analyzing stable state, the direct-coupling method was used, and the frictional heat was calculated by contact pressure, loaded by the function of APDL, distributed by two basically equivalent method—coupling node temperature degree of freedom and set great thermal contact conductance, the load precision of frictional heat was enhanced by iterative calculation. The result of stable state analysis indicated that as for soft mate hard, frictional heat caused greater taper-deformation, smaller contact area on seal face and local high temperature, high contact pressure, high von—stress in contact area. Because the elastic mould of motor was great, the von—stress on motor face was very high, among them the stress of z-direction was main factor.In analyzing transient state, the solution of set small time increment was putforward to avoid initial time too big caused by repetitiveness of frictional heat loading, and the loading of dynamic frictional heat was realized by the method of calculating the frictional heat in current moment by contact pressure in previous moment and table array. The result of transient state analysis indicated the thermal-mechanical effect on seal face during loading, the seal surface parameter dropped steadily during unloading. Considering wear and state of friction,etc. the sealing performance of unloading depended on stability of liquid film on seal face, fast unloading would cause unstable of liquid film and worse of sealing performance.Optimize respect in sealing property, the optimization on the length of stator face along axis direction was done through the optimization module of ANSYS and from contact pressure and contact type. The optimization result can reduce the maximal contact pressure under the condition of contacting in the internal diameter of seal face. As for the local temperature rising, the influence of washing properly and washing limit on sealing performance was analyzed, the result indicated that washing properly can improve the sealing performance notably, washing limit can also improve the sealing performance by a large margin, but washing limit was widely out of reach .