高压工况上游泵送机械密封热力变形与密封性能分析

Thermal mechanical deformation and sealing performance analysis of upstreampumping mechanical seals under high-pressure conditions

为研究高压工况下上游泵送机械密封的性能,考虑密封环与润滑液膜间的流固热力耦合作用,建立了其热弹流润滑模型,基于有限单元方法求解液膜润滑方程、密封环热传导方程和热力变形方程,采用三重迭代算法实现膜压、膜厚、温度和变形之间的耦合求解,研究了转速、密封压力和介质温度对上游泵送机械密封端面变形的影响规律,分析了热力变形作用下密封的上游泵送能力。研究结果表明,高压工况下密封端面产生了沿上游泵送方向收敛的液膜间隙,高密封压力下的力变形是主要原因,热变形部分抵消了压力变形带来的影响;随转速的增大,液膜沿上游泵送方向的收敛程度减小,上游泵送率增大,摩擦因数增大;随着密封介质压力的增大,液膜收敛程度增大,摩擦因数减小,上游泵送率大幅减小;随密封介质温度的升高,液膜收敛程度减小,摩擦因数减小,上游泵送率有所增加。研究结果可为高压上游泵送机械密封环的结构优化和设计提供理论参考。

In order to study the performance of upstream pumping mechanical seal under high-pressure conditions,a thermal elasto-hydrodynamic lubrication model(TEHD)was established considering the fluid-solid thermal coupling between the sealing ring and the lubricating film.Based on the finite element method,the liquid film lubrication equation,the heat conduction equation of the sealing ring and the thermal deformation equation were solved.The triple iteration algorithm was used to obtain the coupling solution between film pressure,film thickness,temperature and deformation of the seal rings.The influence of rotational speed,sealing pressure and medium temperature on the deformation of the end face of the upstream pumping mechanical seal were investigated.And the upstream pumping capacity of the seal under mechanical and thermal deformation were analyzed.The research results indicate that under high pressure conditions,a liquid film gap converges along the upstream pumping direction at the sealing end face,and force deformation under high sealing pressure is the main reason,while thermal deformation partially offsets the impact of pressure deformation.With the increase of rotational speed,the convergence degree of liquid film along the upstream pumping direction decreases,the upstream pumping rate and the friction coefficient increases.With the increase of sealing medium pressure,the convergence degree of liquid film increases,the friction coefficient and the upstream pumping rate decreases greatly.With the increase of the temperature of the sealing medium,the convergence degree of the liquid film and the friction coefficient decreases,and the upstream pumping rate increases.The results can provide a theoretical reference for the structural optimization and design of the upstream pumping mechanical seals for high-pressure conditions.