| In many water conservancy and hydropower projects,the position and shape of the transitional transition are important issues related to the safe operation of the project and socio-economic development.But,due to the limitation of over current width,geological conditions,space layout and other reasons,many projects at home and abroad have to shorten the length of the diffusion section and choose a transition form of large diffusion angle.In this paper,a three-dimensional flow field numerical simulation method is used to study the flow characteristics of the transition section of a plane large diffusion angle open channel and the control effect and optimal design of the delta wing control.(1)Based on the CFD commercial software FLUENT,the mathematical model of open channel in the transition section of large diffusion angle open channel is established.The numerical simulation results are compared with the physical model test results.The results show that the coupling algorithm of the Realizable k-?turbulence model and the velocity pressure of SIMPLEC is more suitable for the study conditions in this paper,and the results are further completed.The parameter rate is determined.(2)The flow of the flow in the diffusion section under the condition of uncontrolled conduction is numerically simulated.Through the analysis of the flow characteristics of the flow in the diffusion section under different flow conditions,including the characteristics of the flow separation,the reflux intensity and the development and change of the reflux area along with the flow development,the influence of the flow rate on the main stream migration and the uncontrolled guide are preliminarily analyzed.The formation mechanism of the mainstream migration in the diffusion section shows that the new reflux region formed during the development of the mainstream migration plays a negative feedback effect on the migration of the mainstream,and prolongs the time required for the migration to be stable.(3)The effect of delta wing control on the improvement of the flow state of the diffusion section is studied through numerical simulation of different flow conditions in the diffusion section.The results show that the delta wing has a distributary function to the mainstream,the extrusion damage to the two sides of the reflux region,the redistribution of the momentum in the diffusion section and the redistribution of the momentum in the diffusion section.The adjustment of flow structure(velocity in the plane and vertical distribution of diffusion section).(4)On the basis of previous research,the optimization control indexes of delta wing shape and position are put forward,such as diverting degree?,latent degree h,control degreeη,attack degree?,fullness b,reflux degree?and position degree?_L,and some of them are studied in the follow-up numerical simulation.The initial optimization value of the attack rate of the 30 degree plane large diffusion angle open channel is 0.75,the initial optimization of the control degree is 0.4,the initial optimization value of the position degree is 0.1.The preliminary optimization design proposal of the triangle wing provides a certain theoretical reference for the follow-up research and application of the delta wing. |
