Experimental investigation of the effect of number of anti-vortex piers on submergence threshold in morning glory spillway with square inlet

Morning glory spillway, is one of the spillways and used when it is not possible to use any other spillways. With the onset of Submergence and flow Loss, and circulation and vortexes intensify, Spillway performance decrease severely. With discharge coefficient decreasing, the height of water in the reservoir increases and Risk of dam damage, caused by the lack of spillway ability of great flow discharge, rises. Anti-vortex piers are used to solving this problem. The increase of the Submergence threshold can provide ability of greater flow discharging, without Spillway submergence and its negative consequences. Anti-vortex piers, in addition to correcting circulation and vortexes, may also be effective in increasing the Submergence threshold. To investigate this possibility, 110 experiments were performed with the physical model on spillways with square and circular inlet section in different modes of number of anti-vortex piers. Results show that increasing the number of Anti-vortex piers increases the Submergence threshold and spillway can discharge greater inflow and height of water without being submerged.