Stability Analysis of Hydrodynamic Mechanical Seals in Multifrequency Excitation

Abstract

The dynamic characteristics of the complex relationship among the sealing system, excitation, and response have a considerable impact on the operational reliability of hydrodynamic mechanical seals, which is a critical issue in the field of sealing theory and technology. Scholars at home and abroad have established dynamic models and calculated the displacement responses of dynamic and static rings in the time domain based on the force on these rings so that the response results can be used for system stability analysis. Neither are the excitation characteristics of cavitation load extracted, nor are the distance response and system leakage rate of the dynamic and static rings analyzed under coupled cavitation and random excitation. In this study, under different operating conditions of the hydrodynamic mechanical seal system, the liquid film evaporation load and seismic load are applied to study the frequency domain response of the distance between the dynamic and static rings and the system leakage rate. The following conclusions have been obtained: Assuming that the chamber pressure is 0.5 MPa and the spring specific pressure is 0.055 MPa, during stable operation, the distance between the moving and stationary rings at 1500 rpm~3000 rpm speeds is 1.12 μm~3.05 μm. For a specific spring pressure of 0.055 MPa, medium pressures of 0.2 MPa~1.0 MPa, and spindle speeds of 1500 rpm~3000 rpm, the excitation force is 30 N, and the frequency is 30 Hz, And the seismic load is assumed to be sinusoidal, the excitation force is 6 N, the fundamental frequency is 120 Hz, and the system leak rate is in 0.1 mL/min~1.3 mL/min. Under multi-frequency excitation coupling, the distance between the dynamic and static rings will decrease as the pressure of the medium in the sealing cavity increases, and this will increase with the increase in the rotating speed. The leakage rate of the system will increase with the increase in the rotating speed and the pressure of the medium, and the test value is largely consistent with the theoretical value.