Research On Energy Dissipation Characteristics Of Fish Scale Weir And Its Influencing Factors

In order to promote the ecological construction of beautiful rivers and lakes,improve the hydrophilicity of wading buildings,and maintain the original ecological beauty of rivers and lakes,under the promotion of the construction of beautiful rivers and lakes,a number of river remediation projects in Zhejiang Province will be carried out on the existing overflow slopes.Renovation,has built various forms of novel artistic barrage.The fish scale weir studied in this paper is beautiful in shape and novel in structure,which can not only meet the functions of normal flood control and drainage,farmland irrigation,etc.,but also can be integrated into the ecology of rivers and lakes,adding a beautiful scenery to the beautiful rivers and lakes.Due to very little research on the energy dissipation characteristics of fish scale weirs at home and abroad,the geometric parameters of fish scale weirs,the relationship between parameters and energy dissipation effects,and the flow state and flow field distribution characteristics during overcurrent have not been systematically studied.At present,there is no mature theory to support the design and promotion of weirs and dams in practical projects,so it is necessary to conduct in-depth research on the energy dissipation characteristics of fish scale weirs.This paper focuses on the energy dissipation characteristics of fish scale weirs,and uses theoretical analysis,physical experiments,and numerical simulation analysis methods to carry out research.Firstly,the energy dissipation rate ? of stepped weirs at home and abroad is studied through theoretical analysis,the calculation method and formula of energy dissipation rate ? are understood,and the possible influencing factors of energy dissipation rate ? of fish scale weir are analyzed.The characteristics of the weir are observed,the variation law of the starting point of aeration on the weir is summarized,and the energy dissipation characteristics such as water surface line characteristics and flow velocity are studied,and the relationship between the energy dissipation rate and the water head on the weir is analyzed.FLOW-3D software analyzes some energy dissipation characteristics of the weir,expounds the influence of ? value on the aeration effect,summarizes the effect of ? value and h value on flow velocity and pressure,and obtains ?value,h value and the energy dissipation effect of fish scale weir,compare the test results and the relevant data of the simulated calculation values to verify the reliability and rationality of the model establishment;finally,based on the work done in this paper Summarize the shortcomings and give an outlook.Based on the analysis of the energy dissipation characteristics of the fish scale weir in this paper,the following conclusions are drawn:(1)As the water head h on the weir increases,the smooth flow area on the water flow surface expands step by step until the entire water flow surface on the weir forms a smooth curve.(2)In the range of ?=135°?180°,the larger the ? value is,the more obvious the aeration effect is on the steps of the fish scale weirs.Through physical experiments and numerical simulations on the aeration point of the fish scale weirs,it can be seen that the aeration starting point on the fish scale weirs step gradually moves down along the step with the increase of the h value of the water head above the weir,the aeration effect is inversely proportional to the head h above the weir.(3)With the change of the water head h on the weir,a clockwise vortex appears at the concave corner of the step.The vortex itself has frictional force with the upper main body water flow,and then continuously consumes the total kinetic energy of the upper main body water flow.The existence of the vortex is a fish scale weirs.One of the main reasons for energy dissipation.(4)When the head h above the weir increases,the average flow velocity along the section of the fish scale weirs increases accordingly;the value of the arc angle ? increases,and the average flow velocity along the section of the fish scale weirs is small.(5)Based on the numerical analysis results,the influence of the arc angle ? value of the fish scale weirs and the h value of the water head above the weir on the energy dissipation rate is obtained,and the technical support and theoretical basis for the construction of the fish scale weirs in the actual project are provided.,the arc size ? of the fish scale weirs should be selected as 180°,and the energy dissipation effect of the weir is the best at this time,and the energy dissipation effect under low head is better than that under high head.Figure [58] table [21] reference [80]...