| This project is supported by the National Natural Science Foundation of China,"dynamic study of cylinder Spiral Groove dry Gas Seal Lubrication Film" :(51565029).With the rapid development of the machinery industry and the demand of the manufacturing market,the axis End-sealing rotary machinery continues to break through the design conditions and gradually develops into extreme working conditions,which is a huge challenge for sealing.In the traditional labyrinth seal,Various factors lead to increased seal leakage,poor stability,and short life,such as the excitation of the airflow and dry grinding of rotor system,.The cylindrical spiral groove dry gas seal can be applied to extreme working conditions with the advantages of less leakage,less wear,long life and compact structure.,this paper researched the cylindrical gas film sealing based on the theory of thermal fluid-solid coupling.The overall model of the floating ring-sleeve-cylinder spiral groove gas film was established by Solid Works.Based on the computational fluid dynamics theory,the three-dimensional flow field and temperature change of the cylindrical spiral groove gas film were solved by Fluent software,discussed the effects of speed and differential pressure on micro-gap film pressure,temperature,leakage and opening force.It is concluded that the pressure and temperature is relatively high in the region where the dynamic pressure effect is most obvious.As the pressure difference increases,the pressure of the film,the amount of leakage and the opening force also increase,but the effect on the temperature field is not large.With the increase of the rotational speed,the pressure,temperature and opening force of the film are continuously increasing,and the leakage amount is increased slightly.On this basis,obtained the optimal selection range by changing the parameters of the micro-gap gas film flow field,such as opening force,leakage amount and stiffness and comprehensively comparing the effects of sealing performance parameters,the average micro-gap thickness is15?m and below,the axis optimum choice for the length of the film is 28-52 mm,the optimum eccentricity of the film is 0.55-0.75,the number of grooves is 16-22,the groove length is26-30 mm,and the optimum spiral angle is 28-42.Divided the floating ring and the bushing into different global Mesh size by the Mesh meshing method,and performed three-dimensional force strain,thermal strain and thermal coupling on the floating ring by coupled Fluent and Mechanical APDL together,discussed the influence of different pressure difference and rotational speed on the sealing ring under the force,thermal coupling strain,as well as on the seal ring force stress,thermal stress and coupling stress.The results show that thermal coupling plays a dominant role in thermalcoupling strain,and the strain scale of thermal coupling in seal ring is much larger than that of mechanical coupling strain.The floating ring and sleeve are mainly affected by thermal stress,the maximum stress appears in the constrained position,is the secondary stress,and is far less than the allowable stress of the material,so it has little effect on the strain,the material of the floating ring should choose the graphite with self-lubricity,the friction can be reduced effectively,which is beneficial to the stability of the sealing system.The moving ring bushing should selected for silicon carbide material with high elastic modulus and low coefficient of thermal expansion.The main factor affecting the thermal strain is thermal expansion coefficient of the material,The lower the thermal expansion coefficient,the smaller the strain.The thermo-mechanical coupling strain is mainly affected by the rotational speed,but the pressure difference is not significant. |
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