Simulation Of Horizontal Plate's Water Film Flowing And Breaking Up

The problem of water films flowing fluctuating and breaking up widely exists in many types of industrial equipment such as thermal engineering and energy sources. The key to discover the character of water films flow wave and break up depends on developing and perfecting methods on it. Based on the basic principles of fluid mechanics, and through reasonable assumptions and simplification, mathematical models of films flow fluctuate and break up have been set up respectively, and then simulated by computer programs.For water films' flow model with no wave, the thesis uses Finite Volume Method to disperse the governing equations, uses upwind scheme for convective term, and central difference scheme for diffuse term. The discrete equation is solved by under-relaxation iterative method. The numerical simulation results show that the key factor affecting the water film velocity distribution is the vapor velocity. For water film fluctuate, after dimensional analysis and get the simplified governing equations, the thesis uses difference scheme controlled by the weight factor to disperse the governing equations and Donor-Acceptor Method to disperse the fluid volume equations, then tracks the free interfaces by VOF method, and gets the wave curve of the film. It is found that the increase of the entrance's film vibration frequency would conduce the decrease of the film fluctuation amplitude, and this amplitude would be smooth follow the direction of film flow.Based on the surface tension model, the guideline for judging the film breakup is given. The water film would break up when the shear exerted by vapor flow is bigger than the horizontal component of film surface tension. This guideline is added on the program of wave, then the theoretical velocity of the film breakup is calculated. The rule of water film broken velocity with the steam wet is also obtained. The steam critical velocity at which the water film breaks would decrease linearly with the increase of the steam wet. The research would be helpful for research on broken velocity of corrugated-plate moisture separator.