丝网分离器水滴撞击水膜的机理研究

运用VOF多相流模型，对丝网分离器内水滴撞击网丝表面沉积水膜的过程进行数值模拟，研究和预测大水滴在较高汽速条件下撞壁产生二次携带的机理。深入研究水滴因素，如水滴大小、初始速度和水膜厚度对丝网的二次携带现象的影响，为丝网分离器设计提供参考。数值结果分析表明，水滴的大小和撞击速度是影响撞击飞溅发生的主要原因，飞溅生成的二次小水滴是造水装置丝网分离器二次携带的重要组成。丝网分离器内水滴撞击网丝水膜能否发生二次携带取决于阈值K_cr＝Oh•Re^a，当K大于K_cr时必然产生二次携带。

Study on Mechanism of Water Droplet Impinging on Water Film in Wire Mesh Demister

Numerical study on the process of water droplet impinging initially on water film deposited on wire mesh surface in wire mesh demister was carried out through the VOF multiphase flow model to predict the mechanism of re entrainment caused by big droplets under rather high steam velocity. In this paper, an intensive numerical simulation to study and evaluate the influencing factors of droplets, such as droplet size, initial velocity and water film thickness on re-entrainment phenomenon, was presented to support the design of wire mesh demister. Numerical results show that water droplet size and impacting velocity are the two main factors to influence the occurrence of splash, and the resulting secondary small droplets are the important proportion of the re-entrainment in a wire mesh demister of freshwater generator. Whether or not splash occurs when a big droplet impinging onto the wire mesh depends on the threshold K_cr＝Oh•Re^a. And when the value of K is greater than K_cr, the re-entrainment will appear definitely.