Numerical Study On Non-contact Mechanical Seal Used On High Temperature Pumps

Contact type mechanical seals are widely used in high temperature hot oil pump in the petroleum and petrochemical industry, but their lifespan is short and performance is bad, and a series of safety accidents would be caused in the event of leakage, so the non-contact mechanical seal was improved, whether this kind of oil seal oil pump could be used in the high temperature pump and achieve zero leakage, also need theoretical research to carry on.Ring, fluid film and static ring of spiral groove gas film seal and spiral groove liquid film seal are treated as the research objects respectively in this paper, model GAMBIT, and the three-dimensional flow field and temperature field are numerical simulated by means of computational fluid dynamics software FLUENT. The internal flow field and the velocity field of fluid film are got by solving the three-dimensional N-S equations, the fluid film and static ring end face temperature field are got by solving the energy equation and calculating convective heat transfer coefficient of the ring and static ring end face. According to the FLUENT simulation results, the temperature of the sealing rings in the high temperature heat pump are high, and there is a certain temperature difference between ID and OD, especially for the liquid film seal, so assuming the same viscosity distribution of gas film and liquid film are not accurate. Therefore the sealing gas and sealing liquid viscosity-temperature equations at high temperature are calculated in this paper, and imported to the FLUENT software, then the flow fields,temperature fields and related characteristic parameters of the gas film seal and fluid film seal in consideration of viscosity-temperature effect were calculated, the characteristic parameters and the end face temperature changing rules with rotational speed and pi/po were studied, and then the calculation results of considering between the viscosity-temperature effect and without considering the effect of viscosity-temperature were compared and analyzed. Though the accuracy of the calculation results would not be affected seriously when considering nitrogen viscosity-temperature effect for hot oil pump, due to the exact demands of sealing performance, a more accurate evaluation and calculation must be given to the characteristic parameters of gas film seal, so considering the viscosity-temperature effect is necessary. There is a big gap between the calculation results of liquid film seal when considering the viscosity-temperature effect and not considering the effect of viscosity-temperature, as it were, assuming a constant viscosity of liquid film is incorrect, the changing viscosity of lubricating oil with temperature must be considered into the liquid film seal before simulated. Therefore, there is a crucial influent that viscosity-temperature effect on the performance research of the hot oil pump non-contact mechanical seal.