Finite Element Numerical Simulation On The Wave-tilt-dam Mechanical Seals

The Wavy-Tilt-Dam(WTD) non-contact mechanical face seal with taper face is widely applied in the submarine stern shaft sealing at high pressure and high speed as a result of circumferential waves developing hydrodynamic effect and hydrostatic effect. Due to the failure induced by the evaporation of lubricant film on extreme conditions during the operation, such as the influence of temperature rise on seal surfaces by viscous shearing action, so it is important engineering significance to the theory of WTD seal design.Firstly, based on the fluid lubrication theory with concerning JFO cavitation phenomenon existing in lubrication film, a two-dimensional mathematical model of WTD was built to analyze the sealing performance, such as opening force, leakage rate, friction and film stiffness, with the SUPG finite element method for solving Reynolds equation, and a comparison was with the literature by Lebeck to vertify the accuracy of this theory. On the basis of the film pressure distribution, the influence of operating and geometric parameters on sealing performance has been presented. The results showed a hydrostatic effect is primary for the WTD seal while the rotor is at a low speed, and a dynamic effect is primary so as to the occurrence of cavitation while the rotor is at a high speed.Secondly, considering the viscous heat generation of fluid film and the heat transfer between fluid film and seal rings, a coupled heat transfer model was proposed on a wave-tilt-dam mechanical seal. The Reynolds equation and heat transfer equation with the energy equations have been solved to investigate the temperature distribution of seal rings and lubricating film with varied parameters, such as the film thickness, wave number, wave amplitude, ratio of seal dam to seal breadth, rotation speed and seal pressure. The results showed that the waves can greatly cool the seal faces, and the temperature of seal rings and fluid film decreases with the increasing film thickness and the wave amplitude, but increases with the increasing rotation velocity and the ratio of seal dam to seal breadth. The wave number and the seal pressure have not significant influence on temperature distribution.Thirdly, based on the pressure and temperature distribution of the lubricating film, a comparison of sealing performance with thermo-hydrodynamic lubrication is carried out with one without that. The results showed that: When the rotation speed is high, the influence of the thermal effect on the sealing performance is significant, and it can not change the pressure distribution of lubricating film, but reduced the maximum pressure of the film, weakened the cavitation zone.