Detection of frost plugs in discharge ducts using an acoustic method

The formation of frost plugs inside discharge ducts during winter season is a risk in hydroelectric power plants. These ducts are mechanically designed to transport water in an open channel flow. The presence of a frost plug, if not detected early enough, might force the transition to a closed conduit flow. Regular controls are carried out by operators to detect the existence of frost plugs. In this study, an automatic detection approach based on an acoustic method is investigated for an early frost plug detection. The method is based on the principle of an acoustic wave reflection in presence of an obstacle. The results of an experimental campaign on a discharge duct permitted to validate the technical feasibility of the proposed methodology.