Investigation into the Water Exit Behavior of a Cavity

Launching-type ship lifts are commonly used in navigational mountain rivers to realize river channelization and communicate different water systems. However, the complicated water-gas-solid coupling process incurred during the water exit of cavities beneath a ship chamber can strongly affect the stability of the chamber and even affect the ship lift operation. In this study, the water exit behavior of a generalized cavity model was investigated using an experimental-numerical approach. Both the air pressure and flow patterns during the water exit process were analyzed. The results demonstrate three different types of air pressure process in cavity exits. Based on the results, a series of relationships are proposed to predict the maximum negative pressure incurred in the water exit process. Moreover, a method was developed to determine the optimum ported area of the cavity regarding the absence of additional hydrodynamic loads. Furthermore, a classification system to typify the flow patterns manifesting in the cavity is proposed. It was found that the transition from a slug flow to a drop flow could be determined as a transition coefficient K equal to 1.