A 1-D Mathematical Model and 3-D Numerical Simulation of High-Pressure Ballast Tank Blowing and Venting Operations

• Main Authors: Wang, Wei-Yi, 王威譯
• Other Authors: Tsai, Shun-Feng
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/5zqxn3

碩士 === 國立臺灣海洋大學 === 輪機工程學系 === 107 === The submersible float control system is an important safety device for water downloading, in which the ballast water tank plays an important role in emergency floating or dive. When the main water tank is full of water, the weight of the vehicle increases and dive; in the event of an emergency, compressed air is blown into the ballast tank from the high pressure gas cylinder, forcing the water to drain and reducing the weight. In this paper, the theoretical model derivation and calculation of one-dimensional gas drainage and drainage for the main water tank drainage system is carried out. The one-dimensional mathematical system is solved by Matlab® Simulink to quickly estimate and confirm the emergency flushing drainage time. In order to verify the correctness of the one-dimensional mathematical model, Ansys® Fluent was used to simulate the three-dimensional real ballast water flushing and drainage, and the one-dimensional mathematical system and three-dimensional numerical simulation data were compared to confirm the practicality of one-dimensional numerical simulation. The ballast tank flushing and drainage system consists of a ballast tank, a high pressure gas cylinder, an intake valve, a nozzle and a pipeline. When the high pressure cylinder inlet valve is opened, the high pressure air is injected into the ballast tank through the nozzle and the high pressure pipeline, so that the gas pressure in the cabinet is increased to force the water to pass through the bottom through the sea valve. The research results show that the nonlinear differential equation system of the main water tank is solved by Matlab® Simulink, and the emergency gas drainage process of the ballast water tank at the depth of 100m (10bar) underwater is compared with the literature. Observing the comparison chart, we can find both The trend of export quality flow rate is the same. Finally, the completion time of the gas is very similar. The horizontal cross-sectional area of the three-dimensional actual complex external system is slightly different with different heights. The difference in water level after the gas injection causes the internal and external pressure changes to be different. Drainage flow. The one-dimensional flushing drainage model of the ballast tank in this study can be used as an auxiliary model for water downloading with a six-degree-of-freedom control system to improve its handling.