Research Of Dynamic Pressure In Mechanical Seal Under Variable Condition

Variable condition always leads to mechanical seal failure of hot oil pump in practical production, which has a big influence on the safety of production. Therefore, it’s necessary to study the principle of mechanical seal and grasp its law in order to design reasonable structure and maintain the stability of the seal. Most studies at home and abroad of dynamic pressure in mechanical seal were for mechanical seal with grooved faces. Research of dynamic pressure about contacting mechanical seal under variable condition was studied by theoretical analysis, numerical simulation and experiment in this paper, through which effects on sealing performance by different parameters can be obtained.By developing computer program, dynamic pressure of mechanical seal in hot oil pump under variable condition was studied theoretically and its influencing factors was analyzed in this paper. Conclusions were drawn that dynamic pressure value reach to the maximum near the middle of the sealing face and its distribution curve is roughly sinusoid with angular displacement of rotating ring. Dynamic pressure value is different by the tilt angle and its effect is more obvious near the middle of the sealing face than at the external or inner diameter.Numerical simulation of pressure and temperature field in mechanical seal was done using FLUENT and ANSYS in this paper and the distribution of pressure and temperature were obtained, which provide a theoretical basis for the analysis of experimental data.Conclusions were drawn by the experiment that film pressure increases with the increase of rotational speed and pressure of medium. However, the latter has a greater impact on film pressure compared with rotational speed, which is consistent with the result of numerical simulation. Changes of rotational speed, pressure and temperature of medium can lead to different value of the ending face temperature. Vacuation leads to the inclined opening of end face. Therefore, motion of end face is periodic in the process of continuous evacuation under the influence of dynamic pressure effect. The appearance of dynamic pressure increases opening force of the end face which makes it open and oscillate periodically and unsteadily and this is in accordance with the result of theoretical analysis. Dynamic pressure effect is more obvious and the proportion of dynamic pressure is greater with the increase of rotating speed and temperature of the medium, which result in unsteady motion state of the face and the increase of pressure fluctuation leading to the seal failure.Solutions were put forward at the end of the paper in order to avoid the seal failure caused by dynamic pressure in mechanical seal under variable condition, which provide theoretical guidance to the continuous and safety production of hot oil pump.