关键词: 动压型机械密封, 汽化特性, 密封性能, 工况参数

Abstract: To study the vaporization characteristics and sealing performance of liquid films for dynamic pressure mechanical seals, a computational model of liquid film vaporization in the sealing gaps was established involving the relationship between saturation temperature of water and pressure, viscotemperature effect and Newtonian fluid internal friction effect. Taking the spiral groove mechanical seal as an example, the influences of working conditions on the liquid film vaporization characteristics and sealing performance were analyzed. The results show that when the temperature of the medium increases, there is a critical temperature value where the average vapor phase volume fraction suddenly increases and the critical temperature value increases as the rotating speed increases. The increase of medium pressure and rotating speed has an inhibiting effect on vaporization. Increasing the rotating speeds tends to reduce the higher degree of vaporization quickly and a sudden change occurs at a certain rotating speed. The abrupt rotating speed may increase with the increasing of medium temperature. The sealing performance is obviously affected by the change of working conditions, especially the rate of change in sealing performance increases rapidly at critical vaporization temperature and abrupt rotating speeds. The liquid film vaporization first occurs in the leeward weir areas of spiral groove and rapidly covers the weir areas and advances to the dam areas with the increasing of medium temperature. With the increasing of rotating speeds, the circumferential distribution of the vapor phase of the lubrication film is more uniform and the high vaporization areas move to the outside diameter side.

Key words: dynamic pressure mechanical seal, vaporization characteristic, sealing performance, operating parameter