泵出型螺旋槽机械密封端面间隙气液两相流动数值分析

针对泵出型螺旋槽气膜密封由于阻塞气压力降低,被密封液相介质进入密封间隙的情况,以密封端面间隙流体膜为研究对象,利用Fluent软件VOF模型模拟阻塞气压力恢复到正常值时端面间隙的流动状况。此时流体膜处于气液两相非稳定流动状态,研究密封端面间气液两相介质分布、压力分布及密封性能随时间的变化规律。结果表明:在假设条件下,内径处阻塞气压力恢复到正常值,流体膜能够恢复成纯气相流体膜;液相介质能增强流体动压效应,增大气相介质流动阻力,降低泵送量;气液两相掺混,改变了气液两相分布、压力分布、泵送量等密封性能,增大了流体膜恢复成纯气相的难度,且在液相介质进入螺旋槽状况下,流动过程中少量液相介质在内径处发生泄漏。

Numerical analysis on gas-liquid two-phase flow of outward pumping spiral-grooved mechanical seal clearance

As the blocking gas pressure of the outward pumping spiral-grooved gas film seal decreases, the sealed liquid enters into the sealing clearance. In this paper, the fluid film between the seal interface was studied by using the VOF model of the Fluent software. The unsteady gas-liquid two-phase flow process of the fluid film between the seal clearance was simulated as the blocking gas pressure was back to normal. The phase distribution of the gas-liquid two-phase, pressure distribution in the seal interface and sealing performance changing with the time were studied. The calculated results show that under the postulated conditions, as the blocking gas pressure in the inner diameter returns to normal, the fluid film could restore to a pure gas phase film. The hydrodynamic effect could be enhanced by the sealed liquid medium. The pumping rate was reduced as the flow resistance of gas medium increased. The mixing of the gas-liquid changed the sealing performances of pressure distribution, pumping rate, phase distribution of the gas-liquid, and increased the difficulty of the fluid film to restore the pure gas phase. When the sealed liquid medium entered into the spiral groove, a small amount of the sealed liquid leaked in the inner diameter during the flow process.