| Dry gas seal is a new type of non-contact gas seal.It has been widely used in various industrial and agricultural rotating equipments because of its advantages of less leakage,good applicability,long life,low power consumption and low failure rate.With the development of dry gas seals maturing,there are also some problems,such as there will be friction and wear during unsteady operation,the gas film is instabe due to external conditions,and the effect of improving the dry gas seals performance by merely changing groove structure parameters under the existing conventional model is becoming weaker and weaker.Studies have shown that the micro-structures of the surface-interface between the relative sliding friction pairs can reduce friction and wear,improve lubricity and sealing performance.In this topic,the idea of setting up micro-structures on the end face of sealing ring is adopted,and micro-holes are formed on the surface of the static ring,and spiral grooves are formed on the surface of the moving ring.According to the dry gas seal moving and static rings motion law,the gas film in the clearance of the end seal ring is extracted as the research object.The calculation domain model of the micro-texture composite lubricating film and only spiral groove lubrication film is established by SolidWorks software.The structured grid of the lubrication film is meshed by ICEM software with unique block mashing technology,and the CFD flow field analogue simulation software Fluent is used to analogue simulation the flow field.By comparing and analyzing the lubricating film pressure,velocity and wall shear force nephogram,which obtained from the analogue simulation of the micro-texture composite lubricating film and the single spiral groove lubricating film,it can be concluded that the micro-texture composite sealing end face can play a positive role in improving the performance of dry gas seal.Based on the dry gas seal working conditions,the medium pressure and the rotational speed are taken as the starting point,the coverage ratio of the micro-holes and the micro-holes structure parameters,density,depth and diameter are changed at the same time.Then,the four aspects of the opening force,leakage,friction coefficient and wall shear force of the film are discussed.The results show that when the micro-holes coverage ratio is the same,with the increase of medium pressure and rotational speed the four parameters,which affect the performance of dry gas seal also increase;when the pressure and the rotation speed are the same,the coverage ratio of micro-holes have a greater impact on the performance of gas seal,the increase is 5% to 8%,and when the coverage ratio is 50% the performance of gas seal can reach the best level.Under the condition of keeping the best micro-holes coverage ratio unchanged at 50%,the density,depth and diameter of the structure parameters of the micro-holes in the calculation domain model are changed.By studying the four parameters affecting the performance of dry gas seal,it is find that the density and diameter of the micro-holes have a greater effect on the performance of dry gas seal than the depth of the micro-holes,the increase is 7%-8%.And the gas seal performance can reach the best level when the micro-hole density is 12.5%,the depth is 10 ?m and the diameter is 400 ?m.Under the condition of keeping the micro-holes coverage ratio is 50%,the micro-holes density is 12.5%,the depth is 10 ?m and the diameter is 400 ?m,the film thickness,groove depth,groove number and spiral groove angle are changed.The calculation data of the analogue simulation is carried out by fitting the gas film stiffness equation,and through comparing the change rule of the film stiffness,it is find that the structural parameters of the spiral groove increase the stiffness of the film by 1.2% to 2%,And the gas seal performance can reach the best level when the spiral groove depth is 16 ?m,the number is 12,and the angle is 60°. |
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