3-D Numerical Simulation Of Scouring Topography In Downstream Of Sluice Gate

Low-head hydropower station with a low head,big flow,small Froude number and insufficient energy dissipation,are built in thick layer with gravel covered.So dam downstream erosion damage occurs very common and some apron is also damage.It even leads to damage to the building and directly affect the safe operation of the sluice.Therefore,it is very important to correctly predict the flow field information,topography and maximum depth of the scouring pit in the downstream of the sluice.This paper conducts a 3D numerical simulation of the local scouring in the downstream of Juting hydropower station,based on the Fluent dynamic mesh technology.The main conclusions are as follows:(1)Based on the SIMPLEC algorithm,the VOF multiphase flow model was used to track the complex free water surface downstream of the sluice gate,and the 3D flow of the scouring pit in the downstream of the sluice gate is simulated by using the RNG k-? turbulence model.The accuracy and reliability of the mathematical model were verified by comparing the discharge flow rate,the distribution of the water surface line,and the velocity distribution on the vertical line of the model.(2)Based on the Fluent dynamic mesh technique,the VOF model was used to track the free surface.In the secondary development of the Fluent software,the bed shear stress was larger than the incipient shear stress as the criterion of mesh movement.Based on the smoothing and remeshing methods,the 3D numerical simulation of the local erosion of single pier was carried out.The numerical results showed that the topography and maximum depth of the 3D scouring pit around pier were in good agreement with the physical experiment results,and the realibility of the development simulation method was verified by the numerical simulation.(3)The 3D evolutionary process of the local scour in the downstream of the sluice gate was achieved.And the topography and maximum depth of local scour obtained by the numerical simulation were in good agreement with the one obtained by the physical model experiments.(4)In the evolutionary process of the scouring pit,the bed shear stress was gradually reduced with the erosion.The variation characteristics of the turbulent kinetic energy on the central plane was similar to that of the turbulent energy dissipation rate.At the initial stage of scouring,the turbulent kinetic energy and turbulent kinetic energy dissipation rate,which were near the bed at the end of slit-type buckets,were large.With the scouring,the turbulent kinetic energy and turbulent kinetic energy dissipation rate were obviously reduced.Finally,when the scouring pit reached the equilibrium state,the turbulent kinetic energy and turbulent kinetic energy dissipation rate in the scouring area were small.