Heat generated by friction between faces of mechanica l seals is a major factor that causes deterioration of the seals and shortens th eir service life. Excessive temperature rise can greatly alter the seal geometry a...Heat generated by friction between faces of mechanica l seals is a major factor that causes deterioration of the seals and shortens th eir service life. Excessive temperature rise can greatly alter the seal geometry and vaporize the sealing fluid, resulting in friction of boundary lubrication. These effects on face seals usually lead to excessive leakage and ultimately ren der the seal inoperable. In order to maintain the reliability of seals, high fri ction and unwanted wear must be avoided. Using the laser-texturing process to produce regular micro-surface structures is a fast and convenient technique compared to some more conventional etching or erosion technique currently used by the seal industry for various grooved face seals. Indeed, by using a pulse laser, better control is obtained on the geometr y, size and pore ratio of seal rings made of metallic or ceramic materials. In t his study, seal rings are made of silicon carbide and carbon. Mating faces of th e rings are polished and only silicon carbide rings are laser-textured. The las er texturing can be controlled to produce spherical pores at selected diameters, depths and pore ratio. The textured rings are then super-polished to remove th e bulges formed on the pores rims. After this process the average pore diameter, pore depth and pore ratio reach the predetermined parameter. Some untextured ri ngs are also treated to the same surface roughness and served as a reference for comparison of the textured rings. A special test rig is used to simulate a mech anical seal system and to measure the effect of the laser texturing on friction and seal performance. Tests are performed at various rotational speeds and vario us axial loads. Compared with the conventional mechanical seals, temperature rise, friction torq ue and friction coefficient of mechanical seals with laser-textured seal faces are much lower. These preliminary results show the potential of improving fricti on performance and increasing seal life with laser-textured seal faces.展开更多
Considering the effect of viscosity-temperature relationship and cavitation of micro-scale film,the influencing factors on hydrodynamic lubrication performance of upstream pumping mechanical seal were investigated bas...Considering the effect of viscosity-temperature relationship and cavitation of micro-scale film,the influencing factors on hydrodynamic lubrication performance of upstream pumping mechanical seal were investigated based on the theory of hydrodynamic lubrication.N-S equation,energy equation,viscosity-temperature equation and vapor transport equation were solved with the finite volume method by using Fluent software,which was performed to analyze the influence of the viscosity-temperature and cavitation effect on hydrodynamic lubrication failure of the film.The research demonstrates that it will lead to the significant difference of the temperature field by considering the coupling of temperature and viscosity.When the film thickness decreases and the rotating speed rises,cavitation regions and viscous friction heat increases,the opening force of the film is also enhanced.However,the growth rate is restricted to the cavitation regions and viscous friction heat,and the opening force begins to decline to a certain extent,and thereby being insufficient to open the surfaces of the seals and leading to the failure of automatic adjustment function and severe wear,lubrication failure occurrs.Through comprehensive research on the influences of viscosity-temperature and cavitation effect on hydrodynamic lubrication performance,the theories of failure and design of upstream pumping mechanical seal are further developed.展开更多
文摘Heat generated by friction between faces of mechanica l seals is a major factor that causes deterioration of the seals and shortens th eir service life. Excessive temperature rise can greatly alter the seal geometry and vaporize the sealing fluid, resulting in friction of boundary lubrication. These effects on face seals usually lead to excessive leakage and ultimately ren der the seal inoperable. In order to maintain the reliability of seals, high fri ction and unwanted wear must be avoided. Using the laser-texturing process to produce regular micro-surface structures is a fast and convenient technique compared to some more conventional etching or erosion technique currently used by the seal industry for various grooved face seals. Indeed, by using a pulse laser, better control is obtained on the geometr y, size and pore ratio of seal rings made of metallic or ceramic materials. In t his study, seal rings are made of silicon carbide and carbon. Mating faces of th e rings are polished and only silicon carbide rings are laser-textured. The las er texturing can be controlled to produce spherical pores at selected diameters, depths and pore ratio. The textured rings are then super-polished to remove th e bulges formed on the pores rims. After this process the average pore diameter, pore depth and pore ratio reach the predetermined parameter. Some untextured ri ngs are also treated to the same surface roughness and served as a reference for comparison of the textured rings. A special test rig is used to simulate a mech anical seal system and to measure the effect of the laser texturing on friction and seal performance. Tests are performed at various rotational speeds and vario us axial loads. Compared with the conventional mechanical seals, temperature rise, friction torq ue and friction coefficient of mechanical seals with laser-textured seal faces are much lower. These preliminary results show the potential of improving fricti on performance and increasing seal life with laser-textured seal faces.
基金National Natural Science Foundation of China(Grant No.51279067)
文摘Considering the effect of viscosity-temperature relationship and cavitation of micro-scale film,the influencing factors on hydrodynamic lubrication performance of upstream pumping mechanical seal were investigated based on the theory of hydrodynamic lubrication.N-S equation,energy equation,viscosity-temperature equation and vapor transport equation were solved with the finite volume method by using Fluent software,which was performed to analyze the influence of the viscosity-temperature and cavitation effect on hydrodynamic lubrication failure of the film.The research demonstrates that it will lead to the significant difference of the temperature field by considering the coupling of temperature and viscosity.When the film thickness decreases and the rotating speed rises,cavitation regions and viscous friction heat increases,the opening force of the film is also enhanced.However,the growth rate is restricted to the cavitation regions and viscous friction heat,and the opening force begins to decline to a certain extent,and thereby being insufficient to open the surfaces of the seals and leading to the failure of automatic adjustment function and severe wear,lubrication failure occurrs.Through comprehensive research on the influences of viscosity-temperature and cavitation effect on hydrodynamic lubrication performance,the theories of failure and design of upstream pumping mechanical seal are further developed.
