Numerical Simulation Study On Hydraulic Parameters Of V-Shaped Submerged Dam Energy Dissipation And Structural Optimization Of Energy Dissipation Facilities

The energy dissipation and anti-scour problem of drainage structures is a very important work in hydraulic structures.The energy dissipation facilities with good effect can reduce the kinetic energy of flow over the dam to the greatest extent,which can not only avoid the scour of buildings on the downstream river,but also play a protective role in hydraulic structures.As a water retaining structure,V-shaped submerged dam is often used in river regulation engineering.It has strong applicability in river management.It not only has the functions of storing and retaining water,but also occupies obvious advantages in drainage.Because of its unique and beautiful appearance,it can create a landscape effect,so it is often used as landscape architecture.At present,there is relatively little research data on flow energy dissipation and impact prevention of V-type submerged dam.According to the model experiment data and the knowledge of hydraulics,the energy dissipation facilities of the submerged dam are designed,and the deep digging-type silencer and silencer type silencer are studied by numerical simulation method.Taking a V-shaped submerged dam as the prototype,a total of 9 groups of combined models under 3 different working conditions were calculated,and the 9 groups of models were divided into unstructured grids by ICEM CFD software.The RNG k-ε turbulence model in Fluent software was used to study and process the free water surface combined with the VOF method,and the three-dimensional numerical simulation calculation under the same flow rate was performed.Through the analysis of the calculation results,the hydraulic characteristics such as flow pattern,surface line,pressure distribution,turbulent kinetic energy and velocity distribution were studied,and the optimization design of the selected pool was carried out.The main research results of this paper are as follows:(1)A study was conducted on the hydraulic jump form of the water flow passing through the V-shaped submerged dam,and it was found that the hydraulic jump form is a far drive hydraulic jump.Based on the characteristics of the water flow behind the V-shaped submerged dam,the energy dissipation method was analyzed,and excavation deep stilling pool and stilling bucket stilling pool were selected as the energy dissipation and erosion prevention measures behind the V-shaped submerged dam.(2)Using Fluent to design a three-dimensional turbulent numerical model,numerical simulation calculations were conducted on 9 combinations,and the distribution maps of water flow patterns under different operating conditions were obtained.Under the same working conditions,the length of the downstream rapid flow section of the stilling bucket type stilling pool is significantly smaller than that of the deep excavation type stilling pool.Both energy dissipation methods can advance the occurrence of hydraulic jump and reduce the hydraulic jump drop.The hydraulic jump drop of the stilling bucket type stilling pool is reduced by 37%to 50% compared to the deep excavation type stilling pool.(3)Using CFD-Post,Tecplot,and Origin software to post-process the calculation results,the energy dissipation effects of the stilling bucket type stilling pool and the excavation type stilling pool were analyzed from five perspectives: water flow pattern,length of the reflux zone,water surface profile,profile velocity,and pressure distribution.The calculation results showed that the stilling bucket type stilling pool can better reduce the length of the reflux zone compared to the excavation type stilling pool.he calculation results showed that the stilling bucket type stilling pool can better reduce the length of the reflux zone compared to the excavation type stilling pool,with a reduction range of 21.3% to 25.7%.For V-shaped submerged dams,the pressure on the lower section of the stilling basin is significantly reduced.The maximum pressure inside the stilling basin is reduced by 21.7%,and the maximum reductions in surface and bottom flow velocities are 24.1% and 22.2%,respectively.This is more beneficial for preventing erosion on both banks and the riverbed.(4)By selecting characteristic sections and drawing cloud maps of turbulent kinetic energy distribution under different operating conditions,it was found that the main channel water flow of the V-shaped submerged dam remained stable under all operating conditions.The downstream river channel was divided into three parts,and the water flow on both sides deflected and diffused inward,causing strong dissipation.When there are dissipation facilities,the turbulent dissipation of water flow energy is more sufficient,and the horizontal distribution of downstream outlet water flow is more uniform.Compared to the deep excavation type stilling pool.When there are dissipation facilities,the turbulent dissipation of water flow energy is more sufficient,the stilling bucket type stilling pool can make the lateral diffusion of water flow more obvious,forming a three-dimensional hydraulic jump,enhancing the dissipation of shear turbulence in the stilling pool,and regulating the flow pattern of the outlet water flow.(5)The orthogonal experimental method was adopted to optimize the design of the stilling basin with a stilling bucket.The optimized model outperformed the pre optimized model in terms of energy dissipation rate,flow velocity of the water passing section,and section pressure.The optimized water passing section reduced the flow velocity by 0.7m/s and 12.1% compared to the pre optimized model;The maximum pressure inside the stilling pool decreased from 33200 pa to 29000 pa,and the maximum pressure decreased by 12.7%.