Numerical Simulation And Groove Optimization Design For A Laserface Liquid Lubricated End Face Seal

A LaserFace mechanical face seal (LF-MS) was invented by John Crane, one of the most famours seal-manufacturing companies in the world, which was regarded as an advanced sealing technology in the late of20th century. The technique greatly improves the lubrication effect between the two faces and effectively controlls the leakage rate. Therefore, it doesn’t require additional cooling system and is specially suitable for sealing easily volatile medium such as hot water, liquid ammonia, liquid hydrocarbon. But so far, John Crane Company has only introduced the advantages of LF-MS products. The theory and method of a LF-MS design has not yet presented. Thus it is necessary to carry out the related investigations.Firstly, based on fluid lubrication theory and taking cavitation phenomenon existing in the lubrication film into consideration, a two-dimensional mathematical model of a LF-MS was set up with mass conservation. To resolve the numerical oscillation problem in calculation process, the SUPG finite element method was adopted to solve Reynolds equation. The maximum fluid film pressure, opening force and leakage rate were calculated. In order to ensure the feasibility of the calculation method, numerical results of these sealing parameters were compared with the correspongding sealing parameters published in the relevant literatures, by which foundation was laid for the further study. Secondly, studies of sealing behavior were completed for a mechanical face seal only with inlet grooves or return grooves onto its surface. Influences on sealing behavior were studied of operating parameters and geometric parameters. Liquid film pressure distribution and density ratio distribution were obtained for the two types of mechanical face seals. The results showed that the inlet grooves introduce the sealed liquid into the faces from the seal chamber and the return grooves return it back. The corresponding seal performance curves were obtained. Thirdly, the seal performance of a LF-MS, which consists of both the inlet grooves and the return grooves onto its surfaces, was analyzed. The optimized geometric parameters of the grooved faces were given. Finally, five nonequal depth groove forms of LF-MSs were presented and the corresponding seal performance was compared. The results showed that a nonequal depth groove LF-MS has little varied liquid film pressure distribution except an enlarged cavitation zone. The nonequal depth structure of a LF-MS can improve the seal performance, especially when a LF-MS consists of the combined grooves, in whcich the intlet groove is convergent and return groove depth is variable.The research achievement will provide theoretical basis for the further study and references for the design of groove structure of LF-MS. So it is of great significance in theory and in engineering.