Gate failure, numerical and physical modelling at Gouin dam

Gouin dam is the main structure on the Saint Maurice river. A gate failure in 2002 prompted this study. Over the years, many modifications and attempts to correct the problems and obtain smooth operation of the bottom outlets were carried out, but with limited success. The numerical results gave a good representation of the flow conditions in the zone of pressure flow before the separation and free surface flow zone but in this latter regime the results were less satisfactory. As a result, a new physical hydraulic model was requested and built. The solution retained has significant advantages when compared to the previous one. In summary, the numerical simulation, due to the power of a strong graphics display, allowed a good preliminary evaluation of the problems. However, a physical model was an essential tool in studying aspects such as air-water mixture and the free surface instability as well as giving information on the vibration and cavitation problems associated with the interaction of high velocity flow and the gate structure. A final solution was found.