Study On Numerical Simulation Of Air-water Two-phase Flow In Open Channel

Aerated water flow is a very important flow phenomena in hydraulic engineering, and is also one of the emphases of study on high-speed hydraulics.Air entrainment changes the flow characteristic largely,which,subsequently,have varies advantaged or unadvantaged effects on hydraulic structures.However,most of studies on aerated water flows,a typical air-water two-phase flows,were carried out by experiments and only a little has been achieved in theory and numerical simulation because of its complexity.Air entrained flows have been studied mainly in numerical simulation field by using of two-fluid model in this dissertation.First,a brief description of aerification mechanisms on air-water two phase current is given,as well the research to aerification characteristic of natural aerified water current is done,additional the aerification conditions are discussed and the formula of aerification quantity is obtained,and the formula shows that the aerification quantity is connected with velocity and critical velocity of flow.Afterward,the anther analyses the main features of air-water two-phase current,obtains a set of equations of natural aerification current of water in open channel.In the numerical calculated method,the way of finite volume method is applied to disperse equations,and discrete form of every equation is inferred.Thereinto,the convection proliferation item applies the QUICK form to carry on the discretization,the pressure-velocity coupling question employs SIMPLER algorithm solution,moreover,the basic solution steps of two phase currents discrete equations are given,then given the suitable boundary conditions,the water's aerification density,the velocity of flow and other parameters of movement for open channel aerification current of water are calculated.From the comparison with the actual material,we can conclude that the model is right and all datas are in reason.The air concentration is larger at the water surface and smaller at the bottom.The vertical distribution of velocity is growing from the bottom to water surface,and then gradually reduced.Finally in a addition a further analysis and discussion of computed results and influencing factors are made,from which we can conclude that the major factors are mathematical model,discrete method,calculated regional,boundary conditions,relaxation factors and so on.The study in this dissertation has provided a good basis for numerical simulation of air-water two-phase flow in future.