| The problems of friction heat of sealing contact interface and vaporization of liquid film induced by deep-sea underwater vehicle in complex service environment will directly affect the reliable operation of the underwater vehicle.Therefore,this paper establishes a double rough surface contact model to explore the contact state of the real interface of the contact mechanical seal under the thermo-mechanical coupling effect,and considers the simultaneous relationship between the micro friction mechanism and the seal macro-structure.At the same time,the performance of the contact mechanical seal is tested and verified,the specific work is as follows:Firstly,the three-dimensional solid model of double rough surface of contact mechanical seal is reconstructed by reverse technology,and the surface contact characteristics,stress distribution and temperature distribution trend of seal rough interface under different parameter loads and velocities are studied.The results show that the contact pressure of the rough surface is 55 MPa during the initial sliding,and the maximum increase of 48.57%during the sliding stage is 48.57%.The maximum fluctuation amplitude of the VonMiscs equivalent stress is 26 MPa;and the maximum temperature of the rough surface is 70.65 ℃ when the load is 0.82 MPa and the speed is 2.51mpm/s.Due to the migration and accumulation effect of the micro-convex body on the double rough surface,the contact temperature rise at the interface of the friction pair changes significantly,and the greater the load,the greater the temperature rise on the rough surface.Secondly,based on the competition mechanism of liquid film vaporization and friction heat at the interface of contact mechanical seal,it is expanded from microscopic to macroscopic liquid film model with rough interface,and the viscositytemperature effect and fluid physical property parameters are simultaneous.The velocity,end pressure,temperature and phase behavior of smooth model and rough model are compared.The results show that the rough model is more affected by temperature,from 478 K to 493 K,and the phase distribution increases with the increase of temperature,in which the vapor distribution of rough model is more at the same temperature.And after 493 K,the degree of phase transition at the exit reached 100%,and the maximum phase volume fraction increased by 11.73%.It is inferred that the vapor phase ratio of the end face decreases gradually with the increase of pressure,while the increase of rotational speed promotes the occurrence of vaporization.Then,the friction performance is tested and analyzed,and the test results show that the friction coefficient of silicon carbide(SSiC)-graphite(M106K)is kept at 0.123 under fixed working conditions,but under periodic fluctuation conditions,the friction coefficient fluctuates,and the effect of load on the friction coefficient is greater than that of rotational speed.Then,in the sealing performance bench test,it is found that there is obvious water vapor in the end cover area of the seal leakage collection port,and the atomization phenomenon is more serious at high temperature,which proves that the temperature rise of the friction pair will lead to the vaporization of the liquid film.Further comparative analysis shows that the test value of 70℃ is highly consistent with the theoretical value,and when the pressure increases to 1.96 MPa,the test leakage rate reaches 2.32 X 1 0-3 mL/s,and the leakage rate decreases slowly with the increase of rotational speed.The leakage rate of 20℃ is significantly higher than that of 70 ℃.This paper mainly studies the face friction state and sealing performance of contact mechanical seal for deep-sea underwater vehicle.The research results of this paper lay a solid theoretical foundation for the future development of mechanical seal for deep-sea underwater vehicle in the direction of high reliability,long life and low leakage. |
