Research On Sealing Performance Of Mechanical Seal With Multi-scale Composite Texture

Mechanical seal is a dynamic sealing device which is widely used in production.The traditional seal face will produce significant friction and leakage under high-speed,highpressure and start-stop phase.By processing the regular distribution of textures on the sealing face,the sealing performance of mechanical seal can be improved effectively and the service life can be extended.At present,the research on the textured mechanical seal is mainly focused on the single texture morphology,and the research on composite texture is mainly based on experiments.In this paper,the effects of multi-scale composite texture and geometric parameters on sealing performance were analyzed systematically by combining theory with experiment.And the mechanism of lubrication,friction reduction and sealing of the mechanical seal were further revealed.Firstly,based on the mass conservation cavitation boundary condition,the mathematical model of multi-scale composite textured end face was established.And the flow field pressure distributions of multi-scale composite textured end face,dimple textured end face,and spiral groove textured end face were obtained by the multi-grid method,respectively.The influence of the multi-scale composite texture and its geometric parameters on seal performance were analyzed.The conclusions are as follows: the dimple and the spiral groove textures on the sealing end face will form convergence zones and divergence zones.The dynamic pressure from the coupling of dimple and groove effectively enhances the loading capacity of the liquid film.Hence,Non-contact face sealing is achieved.The geometric parameters of the multi-scale composite texture have a regular effect on the mechanical seal performance,and there are optimal texture parameters under simulated conditions to make sealing performance optimal.Secondly,By using FM-UVPM-3A processing system,the multi-scale composite texture on end surface of mechanical seal ring was fabricated.Geometric parameters of the dimples and spiral grooves were accurately measured and by laser confocal microscope.The quality of multi-scale composite texture was analyzed.The results show that multi-scale composite texture morphology with high quality can be obtained by determining reasonable parameters of picosecond laser processing,based on multi-pulse scanning method.And the section of the dimple is approximately parabolic and the spiral groove is rectangular,which is consistent with the theoretical hypothesis.Finally,the performance tests of multi-scale composite textured mechanical seal and untextured mechanical seal were carried out in NHMSTS-5 mechanical seal test bench to investigate the effect of pressure of sealing medium and speed on sealing performance.The results are as follows: during static pressure test and operation test,there was no obvious leakage in the textured end face.The friction torque of the multi-scale composite textured end face increases as the pressure of the sealing medium increases,and decreases as the rotational speed increases.In addition,the instantaneous friction torque fluctuation of the multi-scale composite textured end face is small under various working conditions,and the stability of the sealing system is high.The multi-scale composite textured mechanical seal has wide adaptability,and the friction performance under the conditions of high-speed and low-pressure,high-speed and high-pressure,low-speed and low-pressure can be significantly better than that without texture,and the maximum friction torque can be reduced by 55%.