考虑空化效应的螺旋槽机械密封液膜动力学特性研究

考虑液膜空化效应的影响，研究螺旋槽液体润滑机械密封的动力学特性. 基于液体润滑理论和小扰动法，建立了考虑液膜空化的密封微扰膜压控制方程，采用有限单元法对端面液膜三自由度微扰下的液膜刚度和阻尼系数进行了数值求解，分析了不同参数对液膜密封动力系数的影响. 螺旋槽深度在10 μm左右、槽坝比在0.75左右、槽宽比在0.4左右，螺旋角在9°左右时液膜具有最大的轴向和角向刚度系数. 螺旋槽深度在5 μm左右、槽宽比在0.6左右、螺旋角在20°左右时，两角向交叉阻尼绝对值最大. 初始偏角的存在使密封压力呈现非对称性，从而使两角向动力系数绝对值不再相等. 液膜轴向刚度k_zz在数量级上远大于其余液膜刚度值，液膜轴向阻尼d_zz、角向阻尼d_αα和d_ββ远大于液膜其余阻尼值且随着转速和间隙的增大而减小. 

Fluid Film Dynamic Characteristics of Spiral-Grooved Mechanical Seals with Cavitation Effect

Considering the cavitation effect in the liquid film, the dynamic characteristics of spiral-grooved liquid lubricated mechanical seal were studied. The perturbation film pressure equations of spiral groove fluid film seal with cavitation effect were presented by the perturbation method based on the liquid lubrication theory. The 3D stiffness and damping coefficients of the liquid film were numerically solved by the finite element method, and the influence of different parameters on the dynamic coefficients of the liquid film was analyzed. When the groove depth was about 10 μm, the groove dam ratio was about 0.75, groove width ratio was about 0.4 and the spiral angle was about 9°, the film gave the maximum axial and angular stiffness coefficients. When the groove depth was about 5 μm, groove width ratio was about 0.6 and the spiral angle was about 20°, the film gave the maximum absolute value of the angular cross damping coefficients. The film pressure was unsymmetrical when the seal rings were misaligned and the cross-angular dynamic coefficients were not equal to each other in the absolute value. The magnitude of the axial stiffness k_zz were far greater than the other stiffness values. The axial damping d_zz and angular damping d_αα and d_ββ was far greater than the other damping values and decreased with the increase of the rotational speed and clearance.