Steady Flow Field Of Tree-like Microgroove Mechanical Seal Performance Research

In the end face micro-groove mechanical seal,the spiral groove sealing device is favored by researchers because of its long service life and strong anti-interference ability.However,in actual production,the classical spiral groove mechanical seal is limited by one-way rotation,which can not provide good dynamic pressure effect when the equipment rotates backwards.Production accidents caused by seal failure are common.In order to solve this problem,scholars put forward the bidirectional rotary groove seal type.Based on the principle of mechanical sealing,this paper proposes a new bidirectional rotary imitation tree groove sealing groove,and studies and discusses its sealing performance.The main research work is as follows:Imitation tree under the working condition of the same parameter slot and spiral groove seal device respectively through numerical simulation,flow field of gas film under different parameters of two kind of groove type sealing device sealing performance,the results showed that the film thickness and groove depth on sealing performance,dynamic pressure effect produced by imitation tree slot is better,higher opening force,at the same time,the leakage rate is bigger also.When the thickness of gas film is 2μm and the groove depth is 5μm～7μm,the sealing performance is better.The opening force of the two types of groove sealing devices increases with the increase of inlet pressure and rotational speed.For the leakage rate,the increase of pressure tends to linearly increase the leakage rate of the two types of groove sealing devices,but the speed has little influence on the leakage rate of tree-like groove sealing.In comparison,the tree-like groove has better sealing effect under the same working parameters.Considering the influence of temperature on gas physical property parameters,the thermal conductivity of gas under specific working conditions was calculated and simulated,so as to analyze the influence of actual gas effect on the sealing performance of imitation tree groove.The results show that compared with the calculation model without considering the actual gas effect,the actual gas effect has a greater effect on the leakage rate of dry gas seal,but a smaller effect on the opening force of gas film.When considering the actual gas effect,the sealing performance of air,nitrogen and carbon dioxide is greater than the ideal value,and the influence on sealing performance is in the order of carbon dioxide>air>nitrogen.For hydrogen,the sealing performance of ideal gas is lower than that of actual gas.It is found that the actual gas effect has little influence on the gas film temperature.By adding oil droplets into gas and using Mixture two-phase flow model,the effects of different parameters on sealing performance of tree-shaped groove in gas-liquid two-phase state were studied.The results show that the gas-liquid phase is obviously stronger than the pure gas phase in terms of the dynamic pressure effect of tree-like groove,but the leakage rate also increases.As for the opening force,it increases with the increase of pressure and speed in both medium states,and the opening force of oil-gas phase is obviously greater than that of pure gas phase.As for the leakage rate,it increases with the increase of pressure and decreases with the increase of rotational speed in gas-liquid two-phase state.In pure gas phase,both pressure and rotational speed increase.The leakage rate of gas-liquid phase is much higher than that of pure gas phase.In gas-liquid two-phase state,the opening force and leakage rate increase with the increase of liquid-gas ratio and oil droplet diameter,and the oil droplet diameter has little influence on sealing performance.In this paper,the static characteristics of the new tree-shaped groove mechanical seal are systematically studied,the actual gas effect is considered,and the sealing performance of the sealing device in gas-liquid two-phase state is studied.For the mechanical seal of the end face micro-groove in service,the sealing performance of the tree-like groove is better than that of the two-way rotation.The research results of this paper lay a solid foundation for the new tree-like groove mechanical seal in groove design,lubrication performance analysis,engineering application and promotion.