Numerical simulation study on turbulence of hydraulic jump with low Froude number

【Objective】The research studied the hydraulic jump characteristic of low Froude number.【Method】By using VOF method in water surface upstream and downstram of the gate and 2-d k-e RNG turbulence model,hydraulic jump with low Froude number(Fr1=2.0-4.5) was simulated numerically.Water depth after hydraulic jump,length of hydraulic jump and distribution of flow velocity of hydraulic jump with low Froude number were analyzed.Furthermore,pressure,turbulent kinetic energy,turbulent dissipation and coefficient of energy dissipation in the hydraulic jump region and the open cannel flow region were studied.【Result】The length of hydraulic jump whose degree of submergence is more than 1.2 is longer than that of calculated by empirical formula,and increases along with the increase of Froude number.The maximum velocity reduces along the flowing of the main flow in the hydraulic jump region,and the reduction of the average velocity in section is small in open channel flow region after hydraulic jump.The pressure distribution of hydraulic jump is closely related to flow aeration.Turbulent kinetic energy and coefficient of energy dissipation are the maximum near the boundary of the main flow and ground droller in the hydraulic jump.The higher the Froude number is,the higher the theoretical and practical coefficient of energy dissipation is.The theory coefficient of energy dissipation is higher than actual coefficient considering the turbulent kinetic energy after hydraulic jump.【Conclusion】Because low-head key water control project has larger flood discharge power,less energy dissipation hydraulic characteristic of hydraulic jump with low Froude number should be seriously considered,and reasonable energy dissipation instrument should be designed to solve its problems of energy dissipation and erosion-control.