Influence of boundary pressure fluctuation on cavitation and performance of liquid film end face mechanical seal

Under the working conditions of flow regulation and fluid excitation, the pump will have a wide range of pressure fluctuation, which is easy to lead to the "instability" of the mechanical seal and affect the safe operation of the pump. By establishing the spiral groove three-dimensional liquid film model, using the Mixture multiphase flow model and the Zwart-Gerber-Belamri cavitation model, the evolution law of boundary pressure fluctuation on the end face cavitation and sealing performance of sealing liquid film is explored. The results showed that there was a phase difference between gas volume fraction fluctuation and pressure fluctuation under the condition of boundary pressure fluctuation. Compared with the pressure fluctuation on the outside diameter side, the pressure fluctuation on the inside diameter side had a greater impact on the end face cavitation. The pressure fluctuation on the outer diameter side had little effect on the sealing performance and had good follow-up, while the pressure fluctuation on the inner diameter side was the opposite. In addition, under the condition of inner diameter side pressure fluctuation, there was a critical pressure that mad the gas phase volume fraction 0, and the critical pressure was related to the fluctuation period. The end face cavitation disappeared, resulting in a sharp change in the sealing performance curve. Based on the research on the influence of boundary pressure fluctuation on liquid film seal, the pump mechanical seal should adopt the form of rotary seal (pressure fluctuation acts on the outer diameter side) to reduce the influence of pressure fluctuation in the pump on the mechanical seal. © 2022 Chemical Industry Press. All rights reserved.