Analysis On Inner Flow Field And Performance Of Mechanical Seals With Spiral Groove And Micro-cavities For Liquid

Mechanical seal is used widely in equipments and systems such as fluid machinery and power machinery. The contacting faces of sealing rings are the dominant faces in the mechanical seals which are keys to determine sealing performance, as well as friction and working life. In order to improve the lubrication of mechanical seal friction pairs, and to achieve no leakage, non-contacting, people process a variety of geometric shapes morphology to produce dynamic pressure effect and pumping effect. The research on inner flow of tip-to-face modeling mechanical seal and lubricant mechanism for liquid has currently become hot spot.In this paper, the internal flow, the sealing performance and lubrication performance of mechanical seals are analyzed based on friction and lubrication theories and viscous hydrodynamic. The geometry model of laser surface textured mechanical seal with spiral grooves and micro-cavities was established by Pro/E and Gambit software. Three kinds of different coupling model were put forward based on different positions of micro-cavity which is on the end face. The inner flow between the faces was calculated applied CFD software, then the results of them were compared to obtain a better position about spiral groove and micro-cavity. Research shows that pumping effect produced by spiral groove can effectively resist the differential pressure produced by the sealing medium on mechanical seal faces with spiral groove and micro-cavities, thus eliminating medium leaking. And micro-cavities can produce a high dynamic pressure, also spiral groove can produce the dynamic pressure too. Under both of them, there will be a dynamic fluid membrane in circumferential direction, realizing non-contacting operation, reducing friction. Comprehensive analyzing pumping effect, dynamic pressure effect and the friction and wear of the tip-to-face, it shows that mechanical seals with spiral groove and micro-cavities which the micro-cavity distribution in the inner side weir area performance best.On the basis of the numerical simulation, three schemes on combination of spiral groove and micro-cavities and laser surface textured mechanical seals with micro-cavities are tested for performance. The results show that the lubrication of laser surface textured mechanical seals with micro-cavities is superior, but the leakage is large. Compared with other schemes, laser surface textured mechanical seals with spiral groove and micro-cavities where micro concave cavity located in the inner diameter of seal ring perform with a good seal, can effectively reduce the friction face wear, and better adaptabilities for high parameters working conditions. Test results consistent with the numerical simulation results.Combination of numerical simulation and experimental results, matching relation between the spiral groove and micro-cavities geometric parameters where micro-cavities located in the inner diameter of seal ring are initially explored. Through the research on the end face of micro-cavities and geometric parameters how to impact performance, on the research conditions in this paper, the recommended geometric parameters of the spiral groove and micro-cavities are presented (16°≤α≤18°,0.6≤β≤0.8,0.5≤σ≤0.8,0.5≤δ≤0.7), providing a useful reference on the design of modeling mechanical seal faces with spiral groove and micro-cavities.