Abstract:

Cavitation occurred at mechanical seal faces is an important factor affecting lubrication properties of the mechanical seal. A computational fluid dynamics model was established from Antoine equation with a consideration of cavitation thermal effect. The cavitation thermal effect on the sealing performance was analyzed and compared to results of commonly used model of viscosity-temperature effect of liquid film on seal faces. The results indicated that the influence of cavitation thermal effect was negligible at low rotating speed whereas weakened the capacity of forming high-pressure region in mechanical seal at high rotating speed, which reduced pumping rate and opening force. Both viscosity-temperature effect and cavitation thermal effect were needed to analyze seal failure mechanism at high rotating speed. The local temperature at the spiral groove was slightly higher from cavitation thermal effect than that from viscosity-temperature effect. With the cavitation thermal effect, degree of cavitation occurred most seriously in the rotating ring face and cavitation space became smaller with the smallest one in groove bottom from the rotating ring face to the stationary ring groove bottom, which was contrary to those by considering viscosity-temperature effect.

Key words: mechanical seal, hydrodynamic lubrication, cavitation, thermodynamic properties, computational fluid dynamics, model, stability

摘要：

机械密封端面空化现象是影响机械密封润滑性能的重要因素。采用计算流体动力学方法，基于Antoine公式，建立了考虑空化热效应的计算流体动力学模型，并与常用的仅考虑端面液膜粘温效应的模型进行对比，分析了空化热效应对密封性能的影响。结果表明：在低转速下，空化热效应的影响可以忽略，但在高转速下空化热效应使上游泵送机械密封的高压区形成能力减弱，泵送量降低，开启力降低；在高转速工作条件下分析密封失效机理时，除了考虑黏温效应之外，还要考虑空化热效应的影响；空化热效应使螺旋槽槽区局部温度比仅考虑黏温特性时稍高；考虑空化热效应时，动环端面空化发生程度最严重，由动环端面沿膜厚方向至静环槽底，空化区域越来越小，槽底空化区域最小，此规律与仅考虑黏温关系时相反。

关键词: 机械密封, 动压润滑, 空化, 热力学性质, 计算流体动力学, 模型, 稳定性