矩形结构壁面上液膜流动特性的数值研究

Numerical study on flow characteristics of liquid film on rectangular structure wall

壁面结构是影响液膜传热传质特性的重要因素之一。采用数值模拟技术研究矩形结构壁面上的液膜流动特性,得到了液膜的自由液面分布及涡结构特性。结果表明:矩形结构宽度w=3.0mm时,液膜下自由液面位置最低。调整矩形结构宽度,液膜上、下自由液面位置呈现相反的变化趋势,但总体效果变化不明显。在改变矩形结构宽度的基础上,随着液相入口流速的增大,液膜上自由液面位置均急速上升,而且w=1.0mm与w=1.5mm时,液膜流动稳定性良好,而液膜下自由液面位置的变化无明显规律;此外,不同结构尺寸的矩形结构内均有近似对称的旋涡存在。不同的矩形结构宽度下,旋涡的大小和产生的位置不同,w=1.5mm时,矩形结构前端处出现小旋涡。

Wall structure is one of the important factors affecting the heat and mass transfer characteristics of liquid film. The flow characteristics of the liquid film on the wall of the rectangular structure were studied by numerical simulation technique, and the free liquid surface distribution and vortex structure characteristics of the liquid film were obtained. The results show that the free liquid surface position under the liquid film is the lowest when the width of the rectangular structure is set as w =3.0 mm. Adjusting the width of the rectangular structure, the position of the free liquid surface above and below the liquid film showed an opposite trend, but the overall effect did not change significantly. On the basis of changing the width of the rectangular structure, as the flow velocity of the liquid phase increases, the free liquid surface position on the liquid film rises sharply. When w =1.0 mm and w =1.5 mm, the flow stability of liquid film is good, and there is no obvious change in the position of the free liquid surface under the liquid film. In addition, there are approximately symmetrical vortices in the rectangular structure of different structural sizes. The size and position of the vortex are different under different width of rectangular structures. When w =1.5 mm, small vortices appear at the front end of the rectangular structure.