波纹填料表面薄膜流体的数值及实验研究

发布时间：2018-07-02 15:00

本文选题：填料塔 + 波纹结构　；参考：《浙江大学》2015年硕士论文

【摘要】：在化工生产过程中,气液两相间接触面积的大小和液相湍动程度是影响传热传质效率的重要因素因素。薄膜流体因其高传热传质系数及动力消耗小等特点而备受青睐。填料表面波纹结构能引起薄膜流动特性的改变,从而提高薄膜流体的传热传质效率。本文简化填料结构,以不同形状的波纹板为研究对象,探究波纹板表面薄膜流体流动特征,结合数值计算和实验方法,开展了如下工作：(1)探究了重力驱动下薄膜流体沿倾斜波纹壁面下落的流动现象。使用开源计算流体力学软件OpenFOAM进行薄膜流动模拟,选择基于VOF法的interFoam求解器进行计算。将得到的模拟结果与文献中的实验结果进行对比,验证模型的正确性和可靠性。(2)探究了三种常见波纹板结构—三角形、正弦形和矩形波纹板表面薄膜流动,进行数值模拟分析。对流动过程中薄膜波动振幅、表面轮廓、法向速度分布等重要参数进行对比,得出如下结论：三种波纹结构在相同条件情况下,三角形的波纹结构更有利于传热传质。(3)设计并搭建了用于薄膜流体流动显示的试验系统,实验以甘油和水的混合溶液为研究对象,测量了不同雷诺数时三种波纹结构表面薄膜流体流动状态。薄膜流体自由表面轮廓和流线图与仿真结果进行了对比,进一步验证了模型的正确性和实验装置的合理性。(4)研究了液体表面张力、液相粘度和波纹板倾斜角度对三角形波纹板表面薄膜流动的影响。发现表面张力存在与否可以引起整个流场的改变,所以在仿真计算过程中不能忽略表面张力动量源项,但在一定范围内表面张力大小对流场的影响不明显。液相粘度较小时薄膜厚度较薄,波动较为剧烈；液相粘度较大时薄膜厚度较厚,波动比较平缓。波纹板倾斜角度对薄膜流动有一定的影响,在不同的倾斜角度范围内,将改变薄膜流动发生共振时自由表面长度。(5)研究了三角形、矩形波纹板几何结构尺寸改变和矩形波纹板倒角形状存在与否对薄膜流动的影响。雷诺数相同时,三角形波纹板和矩形波纹板的ζ值(高度与波长之比)越小薄膜波动越明显。对于矩形波纹板结构来说,有倒角存在的情况下矩形波纹板薄膜波动更明显。(6)基于以上结果,进一步探讨了新型结构—梯形波纹板和锯齿形波纹板表面薄膜流体流动现象。发现梯形波纹板表面薄膜流体流动特性介于矩形板和三角形板之间。对于锯齿形波纹板这种新型波纹结构来说,薄膜波动情况明显比三角形和矩形波纹板薄膜波动情况好,具有良好的薄膜波动特性,是一种值得考虑的新型填料结构。
[Abstract]:In the process of chemical production, the contact area between gas and liquid phase and the degree of liquid phase turbulence are important factors affecting the efficiency of heat and mass transfer. Thin film fluid is favored for its high heat and mass transfer coefficient and low power consumption. The corrugated structure of the filler surface can change the flow characteristics of the film and improve the heat and mass transfer efficiency of the film fluid. In this paper, the packing structure is simplified, and different shapes of corrugated plates are taken as the research objects. The characteristics of fluid flow on the surface of the corrugated plates are investigated, combined with numerical calculation and experimental methods. The main works are as follows: (1) the flow phenomenon of thin film fluid falling along the inclined corrugated wall driven by gravity is investigated. The open source computational fluid dynamics software OpenFOAM is used to simulate the thin film flow, and the interFoam solver based on VOF method is selected for the calculation. The simulation results are compared with the experimental results in the literature to verify the correctness and reliability of the model. (2) three kinds of common corrugated plate structures-triangular, sinusoidal and rectangular corrugated plate surface film flow are investigated, and numerical simulation analysis is carried out. By comparing the film wave amplitude, surface profile, normal velocity distribution and other important parameters during the flow process, it is concluded that the three corrugated structures are under the same conditions. The triangular corrugated structure is more favorable for heat and mass transfer. (3) an experimental system for the display of fluid flow in thin film is designed and built. The mixed solution of glycerol and water is used as the object of the experiment. The flow state of thin film on the surface of three corrugated structures was measured with different Reynolds numbers. The free surface profile and streamline diagram of thin film fluid are compared with the simulation results, which further verify the correctness of the model and the reasonableness of the experimental device. (4) the surface tension of liquid is studied. The effect of liquid viscosity and inclined angle of corrugated plate on the flow of thin film on the surface of triangular corrugated plate. It is found that the existence of surface tension can cause the change of the whole flow field, so the momentum source term of surface tension can not be neglected in the course of simulation, but the effect of surface tension on the flow field is not obvious in a certain range. When the liquid viscosity is small, the film thickness is thinner and the fluctuation is more intense, while the film thickness is thicker and the fluctuation is more gentle when the liquid viscosity is larger. The inclined angle of the corrugated plate has a certain influence on the film flow. In the range of different inclined angles, the free surface length when the film flow resonates will be changed. (5) the triangle is studied. The influence of the geometric structure and the chamfering shape of rectangular corrugated plate on the thin film flow. At the same Reynolds number, the smaller the Zeta value (ratio of height to wavelength) of triangular and rectangular corrugated plates is, the more obvious the fluctuation is. For rectangular corrugated plate structure, the undulation of rectangular corrugated plate film is more obvious in the presence of chamfer angle. (6) based on the above results, the flow phenomenon of thin film on the surface of trapezoidal corrugated plate and sawtooth corrugated plate is further discussed. It is found that the flow characteristics of thin film on the surface of trapezoidal corrugated plate are between rectangular plate and triangular plate. For the new corrugated structure of zigzag corrugated plate, the undulation of thin film is obviously better than that of triangular and rectangular corrugated plates, and it is a new packing structure worthy of consideration.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.2;TQ053.5

【参考文献】