| As the main sealing element of shaft end rotating machinery,mechanical seals are widely used in compressors,engines,pumps and other rotating fluid machinery due to their good bearing performance,high reliability and long service life.However,with the development of China’s modern industry towards integration,lightweight,zero pollution and high speed,the requirements are becoming more and more stringent in the mechanical seals.With the substantial increase of the utilization rate of the mechanical seals,the liquid film cavitation phenomenons and fluid turbulence effects of sealing have a serious of affects on the steady-state performance of the seals.Therefore,the research on cavitation phenomenons and turbulence effects of shaft end face spiral-grooves liquid film seal could not only provide some theoretical basis for the future research,but also conformity with the requirements of energy utilization and industrial development in China.Firstly,aiming at the cavitation effects of the liquid film seals,based on SchnerrSauer’s cavitation model,the commercial software Fluent is used to simulate calculation the flow field of the liquid film seals,and explore the change rule of the cavitation effects under different rotating speed,inlet pressure,groove depth,liquid film thickness and different helix angle.The findings show that results of the sealing performance of the liquid film seals under considering the cavitation effects are less than take no account of it,and the law of influence in working condition parameters and structural parameters are roughly similar.Considering the sealing performance and reliability of the liquid film seals,it is suggested that the grooves depth is 8μm～12μm,the liquid film thickness is 3μm～4μm,and the helix angles is 15°～20°,the sealing device’s performance reaches the best.Secondly,for the liquid film seals under high-speed condition,based on k-ωturbulence model and Schnerr-Sauer’s cavitation model are used to simulate calculation the flow field.The effects of different the flow states,geometric parameters and operating parameters of spiral-grooves on the steady-state sealing performance and the region of cavitation under cavitation effect are analyzed.The results show that the opening force,leakage rate and cavitation region ratio of the liquid film seals considering turbulence are bigger than laminar,and the influence laws are roughly similar of laminar effect and turbulence effect on sealing performance and cavitation region ratio under difference parameters.Under different conditions,the cavitation effects are more likely to produce the outer side of the spiral-grooves,and the cavitation region under the turbulence effect is great significantly larger than laminar.Therefore,the influence of turbulence effect and cavitation effect shouldn’t be ignored in the liquid film seals.Finally,based on the cavitation effect and turbulence effect,the thermal-fluidstructure coupling analysis of the liquid film seals is carried out in the Workbench software,and the influence laws of the cavitation effect on the stress-strain of the sealing ring is explored by the loading pressure field and temperature field.The results show that the stress-strain of the sealing ring decreases striking when the influence of the cavitation effect is considered;With the increase of working parameters,the stressstrain of the sealing ring increase whether consider cavitation effect,but the stressstrain of the sealing ring are less than that ignore cavitation effect,major as a result of the cavitation effect decreases the opening force of the sealing,resulting in the decrease of stress-strain.The deformation of the stationary ring is greater than the rotating ring.The main cause for the material of the stationary ring is soft and easily cause deform,so the deformation of the stationary ring is greater than the roating ring.In this paper,the whole sealing performance of the liquid film seals is calculated and analyzed the macro and micro’s point of view.The research results not only enrich and expand the lubrication theory of the sealing in cavitation effect and turbulence effect,but also provide some technical supports for the future research and application of cavitation effect in high-speed mechanical seal field. |
