Abstract:
Under extreme working conditions such as fluctuating media pressure, high temperature, and high speed, the liquid film seal is disturbed, and its stability is extremely prone to deterioration, which seriously affects its sealing performance. Therefore, in order to find effective methods to suppress disturbances, this study used numerical methods to comparatively investigate the effects of the boundary pressure fluctuations, as well as the effects of media temperature, pressure and rotational speed with considering the viscosity-temperature effect, on liquid film cavitation, load-bearing capacity, leakage characteristics, and end face temperature under groove bottom super-slip design and traditional no-slip conditions. The research results showed that under fluctuating media pressure, there was no phase difference between the fluctuation curves of liquid film cavitation volume fraction, opening force, and leakage rate over time and the pressure fluctuation curve under the super-slip condition. That was, after the disturbance stopped, the liquid film seal could immediately resume stable operation. However, under the no-slip condition, there was a significant lag phenomenon in the fluctuation curves of the above three performance parameters compared to the pressure fluctuation curve. When considering the viscosity-temperature effect, on the one hand, for both slip conditions, the time for the opening force and leakage rate to reach stability was independent of the initial media temperature, initial media pressure and rotational speed. However, the time for the cavitation volume fraction to reach stability decreased with increasing initial media temperature, while the average temperature in the end face groove area increased accordingly. Additionally, the cavitation volume fraction and the average temperature in the groove area were also independent of the initial media pressure and rotational speed. On the other hand, compared to the no-slip condition, the groove bottom super-slip design could significantly reduce the time for the cavitation volume fraction, opening force, leakage rate and average temperature in the groove area to reach stability. It could also significantly increase the opening force, reduce the cavitation volume fraction, and lower the average temperature in the groove area (and could significantly reduce the leakage rate at high rotational speeds). At the same time, the leakage rate was far less than the standard allowable value. Lower initial media temperatures or higher rotational speeds could further enhance the improvement in sealing performance, while the initial media pressure had minimal impact. This study demonstrated that the groove bottom super-slip design could effectively enable the liquid film seal to cope with the adverse effects of complex environmental disturbances on sealing performance. The results provided valuable insights for the design and optimization of liquid film seals in extreme working conditions, and contributed to improve the reliability and durability of sealing systems in various industrial applications.