Investigating the effect of stepped duct and its number on the hydraulic performance of the flow passing through the glory spillway

Spillways are designed in different methods according to the operating conditions, type of structure, site conditions of the dam, and hydraulic characteristics. One of them is the Glory spillway, which consists of a circular opening, a vertical circular opening, and a horizontal pressurized tunnel. The present study investigates the effect of stairs and their numbers as well as the effect of the presence of a vortex breaker on the hydraulic performance of the Glory spillway. This is due to the simplification of the geometric shape during construction and increasing the efficiency of the flow. Based on the results, it was observed with the coefficients of low immersion ratio,4 floors have the highest performance in discharge transfer. Also, increasing the immersion ratio coefficient of stairs will reduce the hydraulic performance of the spillway. On the other hand, in all cases (except in the case of spillway with 12 floors), the presence of a vortex breaker with a triple arrangement can affect the separation of vortex breakers, which ameliorates the flow transfer efficiency from the spillway and separation of flow lines.