The Investigation Of Anti-Rolling Tank Structure Design And Control Method For A Semi-Submersible

Due to the influence of the external environment such as wind and waves from the sea,the ship will produce six degrees of freedom of rocking motion when sailing,which will affect the comfort of the people on the ship and the safety of the cargo.But different from other ships,semi-submersible vessel need to sail on the sea level,and sometimes carry out submersible operations in semi-submerged state,or load other ships or perform submarine rescue operations in full-submerged state.The different working conditions of the semi-submersible ship during navigation will lead to a large range of changes in its roll cycle.At the same time,it has the characteristics of high center of gravity,poor stability,and small restoring torque of the ship,which makes the semi-submersible vessel encounter in long-distance sea voyages.When strong winds and waves strike,they will be more prone to large-angle rolling motions than other ships.Therefore,these ships are usually equipped with anti-rolling equipment when sailing and operating at sea.The most commonly used anti-rolling equipment mainly includes anti-rolling fin and anti-rolling tank,etc.Compared with conventional anti-rolling fin,anti-rolling tank can achieve anti-rolling effect at any speed.In this paper,according to different working condition of the second half of the submersible ship rolling period of the characteristics of big changes of U-shaped anti-rolling tank internal baffle structure design and selection of the corresponding control method to reduce in different working condition of the second half of the rolling motion of the ship.First of all,this paper semi-submersible ship and anti-rolling tank research purpose and meaning,and the current research status at home and abroad are introduced,and presents the paper’s main research content and structure arrangement By analyzing the pose of the ship and anti-rolling tank system to build the ship-rolling motion model of the controlled passive tank,and combining with the waves of ship roll motion,the influence of different working conditions,analysis of the same sea condition the semi-submersible ship itself characteristic and the main factors influencing the anti-rolling tank features,and presents a formula for calculation of damping effect for the subsequent simulation basis for structure design and control of water tank.Secondly,this paper studies the internal baffle structure and baffle control method of the variable period U-shaped anti-rolling tank.Two types of conventional rectangular and T-shaped baffle structures are designed for the interior of the U-shaped anti-rolling tank.The FLUENT software is used to simulate the free attenuation of the tank to obtain the influence of different baffle structures and quantities on the tank cycle.According to the simulation results The structure of the T-shaped baffle inside the water tank is optimized to match the roll period of the semi-submersible vessel under different working conditions.The height of the T-shaped baffle inside the water tank is adjusted to change the water flow block in the water tank.The board control method,combined with the autoregressive model,predicts the roll period of the semi-submersible vessel,and simulates it in MATLAB software to obtain the anti-roll effect of the variable period anti-roll tank.Then,this paper studies the control method of the valve on/off of the U-shaped anti-rolling tank with controllable valve.In order to make the RBF neural network applicable to the rolling motion of the semi-submersible vessel under three working conditions,the smoothness and ergonomics of the semi-submersible ship rolling under the three working conditions are analyzed separately.By combining the prediction method of semi-submersible ship roll half period with the optimal phase control method of tank air valve switch and RBF neural network,the anti-rolling effect of valve-controlled tank is obtained through simulation in MATLAB.Finally,this article carried out a model experiment of a semi-submersible vessel and a valve-controllable water tank,and verified the consistency of the conclusions obtained by the numerical simulation by analyzing the results of the experimental data.