油位高度变化对发电机推力轴承油槽甩油雾问题的影响

针对江西洪屏抽蓄电站推力轴承油雾泄露问题,建立推力轴承三维模型,使用VOF多相流模型、Lee蒸发冷凝模型和RNG k-ε湍流模型,对油槽内的润滑油-空气-油雾三相流热耦合问题进行求解.分析了从低报警油位到高报警油位之间的油位高度变化对油槽内流场分布特性的影响,并探究了不同油位下的润滑油分布规律以及油雾聚集情况,定位了油雾的产生、聚集位置.研究发现:油槽内的流速和温度分布主要由机组转速以及外循环泵的性能决定.油雾在产生之后主要向着2个区域聚集,其一为挡油板与推力头之间的区域,其二为挡油管处的区域,这2个区域具有低压、高温、高流速的特点,最易发生外甩油和内甩油事件.此外,随着油位高速增加,压油叶栅逐渐丧失其阻油雾作用,为了运行安全和环境安全,不建议推力轴承油槽运行在较高油位下.研究可为合理设置推力油槽运行工况参数提供一定的理论基础.

Study on the influence of oil level change on oil mist leakage problem of generator thrust bearing oil tank

A three-dimensional thrust bearing model was established to solve the oil mist leakage problem of thrust bearing in Jiangxi Hongping Pumping and Storage power Station. The VOF multiphase flow model, Lee evaporative condensation model, and RNG k-ε turbulence model were used to solve the lubricating oil-air-oil mist three-phase fluid-thermal coupling problem in the oil tank. The influence of the change of oil level height from low alarm level to high alarm level on the distribution characteristics of the flow field in the oil groove was analyzed, and the distribution of lubricating oil and the accumulation of oil mist under different oil levels were explored. Also, the generation and accumulation positions of oil mist were located. It is found that the unit speed and the external circulation pump performance mainly determine the oil tank velocity and temperature distribution. The oil mist mainly gathers in two areas after it is generated. One is the area between the oil baffle and the thrust head, and the other is the area at the oil pipe. These two regions are characterized by low pressure, high temperature, and high velocity and are most prone to external and internal oil dumping. In addition, with the high-speed increase in oil level, the oil pressure cascade gradually loses its oil mist suppression effect. The thrust bearing oil groove is not recommended to operate at a higher oil level for operation safety and environmental safety. This paper can provide a theoretical basis for reasonably setting the operating parameters of a thrust oil tank.