Effect of using guide walls and piers with different geometries on the flow at entrance of a spillway

Abstract

In the present paper, the effect of guide wall and pier geometry on the flow pattern of a dam spillway was studied. Different scenarios were numerically simulated to optimize the geometry of the guide walls and piers of the spillway in different hydraulic conditions. The RNG and VOF models were used for turbulence and free surface simulations, respectively. Numerical results were validated with experimental data and good agreement was found with an average relative deviation of less than 10%. Results showed that the vertical inclination of the guide wall and pier was the main affecting factor in the approach flow condition through the spillway. A 44% increase in the vertical inclination of the guide wall resulted in a 43% reduction of the turbulence factor and in a 13% increment of the discharge coefficient of the spillway. By increasing the vertical inclination of the piers of the spillway by 28%, the flow behaviour becomes more uniform and the discharge coefficient increases by as much as 11%. Moreover, the results indicate that increasing the straight length of the guide wall leads to a reduction of the depth-averaged velocity and of the turbulence energy in the approach channel.