三维倾斜平板液氧降膜润湿数值模拟研究

建立三维倾斜平板降膜模型,利用VOF两相流模型计算了液氧降膜的润湿情况,研究了工质物性、倾斜角、液膜入口高度对润湿面积的影响。结果表明:Weber数(We)相同时,液氧和水的润湿比均随Kapitza数(Ka)增大而减小;相同Ka下,液氧和水的润湿比均随We增大而增大,而液氧润湿比一直小于水润湿比,两者的差值也随We增大而增大。拟合得到液氧在液膜入口高度0.4 mm、接触角70°时的界面润湿比经验关联式,拟合值和模拟值相对误差≤±20%;在We=0.76时,液氧的润湿比随倾斜角增大而减小,但降低速率随Ka增大而减小;在倾斜角为90°时,易出现液膜脱离壁面的现象;当We固定时,液氧的润湿比随液膜入口高度增大而增大。

3D numerical simulation study on liqiud oxygen film flowing on inclined plate

A numerical model of three-dimensional inclined plate was established, and the VOF model to capture gas-liquid interface was applied to calculate the spreading progress of liquid film on the wall. The effects of the physical properties of studying fluids, inclination angle and film inlet height on the wetted area of liquid oxygen falling film were explored. The results show that both wetting ratios of liquid oxygen and water decrease with the increase of Kapitza number(Ka) at the same Weber number(We). At the same Ka, both wetting ratios of liquid oxygen and water increase as We increases. However, the former results are always smaller than the latter in the study range, and the difference values between two fluids exhibit an increasing trend when We increases. The interfacial wetting ratio for the liquid oxygen under film entrance height 0.4 mm and contact angle 70° is fitted by the nonlinear fitting method, and the relative errors between the calculation formula and the simulation data are controlled within ±20%. The wetting ratios decrease with the increase of inclination angle at We=0.76. However, the decreasing rates of wetting ratios decrease as Ka increase. At inclination angle 90°, the phenomenon that liquid film separates from the wall tends to appear easily. When We is fixed, the wetting ratios of liquid oxygen tend to increase with the increase of the film inlet height.