Triangular labyrinth side weirs with one and two cycles

Labyrinth side weirs provide a potentially effective way to shorten the length of a channel opening with the desired water height, but the discharge coefficient needs to be found experimentally. Experiments were carried out for triangular labyrinth side weirs with one and two cycles in order to obtain the discharge coefficient. The test variables included channel opening, head angle, number of cycles, weir height, upstream water depth and discharge in a subcritical situation. The results show that the discharge coefficient ratio for a triangular labyrinth to a conventional side weir could rise to more than 2 with the same flow and geometric conditions. Relationships for the De Marchi coefficient for subcritical flow in a rectangular channel for triangular labyrinth side weirs (for the two geometries) are introduced as functions of non-dimensional variables of weir and flow. A sensitivity analysis on the measured data is also included.