Dynamic characteristics evaluation of balance valve for seawater hydraulic variable ballast system considering the depth variation

A seawater hydraulic variable ballast system (SHVBS) is used to dynamically adjust the weight of the submersible. The balance valve is a crucial component of SHVBS which has two working conditions called charging and discharging process. In this paper, an experiment simulating the ocean is built to obtain the dynamic characteristics of the balance valve, including the starting pressure and the pressure difference. Then there are analyzed by a kinematic model. The results show that as the depth increases, the pressure difference increases during charging process, while it remains unchanged during discharging process. Charging process is much worse than discharging process for balance valve. When the depth is 600 metres, the pressure difference during charging process is 45 times higher than during discharging process. Furthermore, friction force is the main factor that affects the starting pressure, while the hydraulic force mainly affects the pressure difference.