Analysis of instabilities in the change of regime in morning-glory spillways

The purpose of this paper is to make an analysis of the instabilities of the flow, whose apparition result commonly associated in the transition from a spillway regime to an orifice regime, in the special case of a Morning-Glory spillway. Even though these structures are usually designed to function at free surface, the analysis of the mentioned transition is important in order to quantify the loss of performance in the discharge and analyze the flow-induced solicitations regarding the pressure and frequency fields. The condition given by the beginning of the submergence is particularly analyzed, being this situation related to a condition where strong flow instabilities appear on the spillway profile.