Improving the performance of the compound labyrinth weirs using an artificial ventilation approach

Abstract Compound labyrinth weirs are a new shape that is used to increase discharge. The air pockets behind the nappe flow are a big problem for the hydraulic performance of the labyrinth weirs. The study aims to use the artificial ventilation approach to improve the performance of the compound labyrinth weirs. The current study proposes artificial ventilation techniques to mitigate the pressure behind nappe flow and to improve the coefficient of discharge. The data have been collected for three cases (without vented (WV), with vented (V), and with suction (S)). The results indicated that the pressure distribution behind nappe flow was not similar for all tested points. Also, a slight negative pressure was observed when H′t/P′ was measured between 0.1 and 0.2. Artificial ventilation with a suction pump was the best technique to reduce pressure behind the nappe flow when compared with a vent pipe device. Furthermore, the compound coefficient of discharge (Cdc) using the suction and vent devices was greater than the compound coefficient of discharge (Cdc) without the vent devices by 10% and 4.5%, respectively. The empirical equations were provided to predict the compound coefficient of discharge when pressure data behind nappe flow is available.