Dynamic Characteristic Analysis of Mechanical Seals With Leakage Rate as Response

Abstract Good dynamic characteristics are essential for the safe operation of noncontact mechanical seals. This article investigates a diffuser-type self-pumping hydrodynamic mechanical seal (DSPHMS) by integrating the classical spring-mass oscillator dynamics in the axial direction with fluid lubrication theory. A transient dynamic model with the leakage rate as the response was established in the axial direction. Using the perturbation method, the analytical expression for the leakage rate was derived from the liquid film pressure distribution. The dynamic equations were then solved numerically via the Runge–Kutta method. The effects of rotor mass, bellows stiffness, and periodic excitation (amplitude and frequency) on the dynamic characteristics of the seal were systematically examined. Experimental validation was conducted on a custom-built test rig, confirming the model's accuracy. Results indicate that the rotor mass and bellows stiffness have limited effects on the seal system, whereas the liquid film between sealing faces is the critical factor governing system stability. The leakage rate response amplitude increases with excitation amplitude but decreases with excitation frequency. These findings contribute to enhancing the operational stability of noncontact mechanical seals.