Investigation On Formation And Elimination Measures Of Horizontal Vortex In Side-flow Energy Dissipation Well

Horizontal vortex has a strong entrainment effect,which entrains a large amount of gas into the downstream pipeline,resulting in severe oscillation of the flow and pressure of the downstream water pipeline,which seriously endangers the safe operation of the water delivery system.This paper proposed a method to show the formation and dissipation mechanism of horizontal vortex.The experimental study is about the hydraulic characteristics and the influence factors of the formation and dissipation of horizontal vortex,and put forward measurements to eliminate vortex.The main research contents of this paper are as follows:According to the influence of the bending deformation of the vortex tube on the vorticity,the motion characteristics of turbulence and energy dissipation,a method of formation and dissipation mechanism of horizontal vortex was put forward.The initial circulation over the intake is the cause of the formation and development of the horizontal vortex.By hydraulic model test,the reason of forming horizontal vortex is discussed.The horizontal vortex have the characteristics of "coherent structure" similar to turbulence.The vortex is formed by the entrainment of bubbles into the center of the flow.The vortex is formed by the entrainment of bubbles into the flow center.Bubble separate from vortices mostly occurs at the high point of the cross-axis vortices.The position of the high point always moves with the movement of the abrupt section.The results show that aeration and circulation are the basic reasons for the occurrence of horizontal vortex in side-flow energy dissipation wells.The duration probabilities were obtained for different discharges,submerged depths and overflow widths.The non-dimensional method was used to analyze the formation and dissipation mechanism of the horizontal vortex.Results showed that the duration probability of the vortex increased with the supply discharge when the supply discharge was less than the stable discharge;the duration probability of the vortex decreased with the discharge when the supply discharge was more than the stable discharge.The duration probability of the vortex increased with the water depth when the submerged water depth was lower than the steady water depth;the duration probability of the vortex decreased with the water depth when the submerged water depth was higher than the stable water depth.Moreover,the duration probability of the vortex increased with the overflow width.Based on theoretical analysis and experimental research,the theoretical basis of eliminating horizontal vortex is discussed.According to the relevant theories,the measures of control vortex are summarized,and the relevant engineering measures are provided from aeration,submerged depth,overflow width.These research results can be applied to related works,and three-dimensional nu merical simulation method can be a powerful supplement to model tests,which can pr ovide reference for studying the hydraulic characteristics of water intake,engineering practice and application and have someguidance on similar projects.The conclusions obtained in this study can provide reference for reducing or eliminating horizontal vortex,and the data derived from this experimental can be used for the validation of numerical models and help to establish the transport model of sewer sediment.