Characteristics Research And Experimental Verification Of Controlled Passive Tank

When ship sailing in the marine environment, seakeeping and seaworthiness are effected due to ship motion because of the impact of the external environment. The speed and acceleration produced by the motion caused the uncomfortable sense of the crew, even make equipment on board failure and personnel or goods loss. The roll direction has the greatest impact for mono-hull displacement ship, it is of crucial importance to improve the ship rolling, fin stabilizer, anti rolling tank (ART) and weight stabilizer etc are considered as effective anti-rolling equipments with the development of ship control technology. The ART has the stabilization effect under any speed, although need to occupy hull space, the ideal effect, easy maintenance and simple control make the ART widely use. The ART type in this thesis is primarily a u-shaped structure. The characteristics of the water tank are studied through researching passive tank, and on this basis, valve control and damper control methods are considered. At last, bench test combined with hardware-in-the-loop simulation is used to verify the characteristics and control method.In order to study ship motion coupled the movement of fluid, the "Ship-ART-Waves" mathematical model is developed based on the Hamilton mechanics. The model takes into account multiple degrees of freedom and non-linear factors in the ship motion. For different contents, By simplifying,1DoF roll model and3DoF of roll, pitch and heave model could be obtained on the basis of the6DoF ship motion model. Meanwhile, the solving of the key parameters is analyzed in detail. The ART structure optimization and control methods could be studied on the basis of these models.First, the external form of the tank structure and internal damping structure determines the main characteristics of ART. The external form and structural boundaries of ART depend on the parameters of the ship hull. The ARTs are designed through four different hull parameters. Suitability of ship hull with ART is discussed. For the internal structure of ART, due to the randomness of the state change, and large margin nonlinear movement of fluid, The scholars usually carry on assistant analysis using CFD computational fluid dynamic,such as volume of fluid(VOF), smoothed particle hydrodynamics method(SPH) and moving particle semi-implicit method (MPS), In view of the algorithm’s accuracy and reliability considerations, here with the VOF method to establish the2d and3d CFD model of ART. And free oscillation, sinusoidal and random signal are used as excitation signal to study the flow state variation, including the variation of the flow velocity,the torque, the period of fluid flow and the damping characteristics and so on.Based on theoretical analysis and computational fluid dynamics analysis, the ship hull shape and layout constraints are comprehensive considered. The method of structural design is studied. The methods contain major dimensions, the damping structure and the location. The structural design software for ART is finished. Multi-objective optimization technology is applied for structure design, different ship space layout and constraint conditions are considered, MOO of ART structure design is completed to obtain the optimal parameters.The "Ship-ART-Waves" simulation system is established for researching. Firstly, stabilization effect under different significant wave height, speed and encounter angle is simulated according to ship sailing state. The influence of ART on ship heeling and rolling during constant turning of a ship is analyzed, meanwhile, preventing parametric rolling of ART is compared. The control methods of the controlled passive tank (CP-ART) are researched, including variable period wide band and air valve control. Here, in order to reduce the error caused by the ship rolling period statistical calculations, proposed half period estimation based on WNN predictive control method, the simulation indicated the stabilization effect is better than traditional control.Finally, the qualification of bench test is improved, the bench system could finish high-frequency response motion.The ART test system is established, including controller prototype, semi-physical simulation and experimental system software. The programs of free-delay test, forced-roll oscillation and random signal input test are proposed. Through these test items, the characters of ART including period, damping and frequency response are obtained. The experimental result and CFD results are compared. Under the support of the semi-physical simulation system, simulate the ship rolling motion, the fluid level and ship rolling signal return to the system, the effectiveness of ART controller is verified.