Numerical Study On Hydrodynamic Characteristics Of The Water-air Two-phase Flow Model Test Based On OpenFOAM

In the actual operation of water conservancy projects,the flip-flop energy dissipation is widely used.Among the various research directions of the flip-flop,the hydrodynamic characteristics of the water-air two-phase flow are still the focus of research.Among them,the hydrodynamic characteristics of the jet range,turbulent kinetic energy,etc.The calculation of the elements is of great significance to the layout of water conservancy projects and the study of the characteristics of scouring pits in the scouring range.This paper is based on the numerical simulation software OpenFOAM to numerically simulate the hydrodynamic characteristics of the flip-flop two-phase flow.The basic idea is:first do a physical experiment to measure the parameter of the flip-flop range;then construct a mathematical model of the channel flip-flop and a detection model Meshing quality and optimizing the meshing plan;after that,the range simulation results of the three commonly used turbulence models(standard k-? model,k-? model and k-? SST model)are compared with the measured data of physical experiments.This not only verifies the accuracy of the numerical simulation,but also optimizes the simulation of the turbulence model.Selection scheme;Finally,based on reasonable grid division and turbulence model selection scheme,the numerical simulation results of the two-phase flow of the flip-flop are in terms of the cross-sectional velocity of the water tongue,the energy loss rate,the pressure field of the flow velocity field at the bottom of the canal,and the value of turbulent kinetic energy,etc.A quantitative analysis of hydrodynamic characteristics was carried out.In addition,in Chapter4,the influence of mesh refinement and boundary layer refinement on the numerical simulation results is analyzed.In Chapter 5,Section 1 also compares the measured tipping range data with the tipping range data calculated by two different empirical formulas,and analyzes the difference between the two empirical formulas and their respective advantages and disadvantages.It can be seen from the model test that the water flowed through the sill and then fell,forming a violent water vapor mixing phenomenon where it fell into the downstream water body.In the analysis and comparison of the numerical simulation results,this paper draws the following conclusions: in the aspect of meshing,setting the boundary layer refinement reasonably can significantly improve the accuracy of the numerical simulation results,so it can get a better meshing plan;in terms of turbulence model selection,compared with the standard k-? model and k-? model,the k-? SST model is proved to be more suitable for the numerical simulation of the two-phase jet flow in this article;in the empirical formula to calculate the jet range of the water tongue,if air resistance,side wall friction and water particles are not considered For factors such as movement,the idealized range calculation value will be about 31% larger than the actual value measured in the physical test,which illustrates the importance of considering various resistance factors when predicting the movement of the water body;in the analysis of the hydrodynamic characteristics of the water tongue and the channel water body On the one hand,this article divides the water tongue of the air section into initial section,transition section,split section and broken section according to the shape,and describes them accordingly.When the water tongue moves in the air,with the gradual increase in the pitch of the water tongue,the gap between the center velocity and the velocity at the boundary gradually increases,and the section velocity gradually shows a symmetrical distribution pattern,and the average velocity of the water tongue section reaches behind the highest point.The flow rate is the smallest;the research results of the energy loss rate ? in the mid-air section of the water tongue show that the energy loss rate ? is not a constant constant,and it will continue to increase with the increase of the water tongue range;in addition,the flow rate stagnation point at the bottom of the channel is about It is 20.52 cm from the downstream side of the canal.After that,the flow velocity curve of the downstream channel section gradually transitions from an irregular curve to a logarithmic curve.By drawing the pressure curve along the bottom of the canal,this paper finds the position of the maximum pressure point at the bottom of the downstream canal.Located on the downstream side 21 cm from the canal,the value is 538.7pa.The fluctuating pressure at the bottom of the canal at this position gradually decreases with time.The analysis reason is that the water cushion weakens the change of the canal bottom pressure to a certain extent.Finally,this paper studies the change of turbulent kinetic energy at the bottom of the downstream channel along the course.The change curve shows that the turbulent kinetic energy at the bottom of the channel increases first,then stabilizes and then decreases along the course.This change rule reflects the area where the scour at the bottom of the channel is the most serious,and this is the key part that needs to be protected in engineering practice.This paper combines physical model tests with numerical simulations.Through the research of this paper,it can be seen that the two-phase flow model can accurately simulate the canal flooding problem numerically.This has certain guiding significance for such projects.