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.