Research On U-type Anti-rolling Tank Damping Structure Based On CFD

The structure of the anti-rolling tank is simple and can work at all speeds.As the most widely used anti-rolling device,it is especially suitable for ships such as ro-ro ships,fishing boats,inspection patrol boats,drilling vessels and scientific vessels.The rolling motion is affected by stickiness,the flow in the anti-rolling tank is complex and has strong nonlinearity and randomness.The current theoretical calculation for anti-rolling tanks cannot be used for actual engineering.The numerical simulation method based on computational fluid dynamics(CFD)provides a new means of realization for solving the design problem of anti-rolling tank.In this paper,a ro-ro ship is used as the object,and based on the CFD method,the effects of stickiness and free surface are taken into account.Through numerical simulation,a series of work has been carried out on the anti-rolling effect.The main contents are:(1)Based on Krynov-Blagovicinski's general method for passive U-type anti-rolling tank scale design,the basic dimensions of the tank and some related parameters are designed.(2)According to the design concept of "double resonance",make the natural cycle of the tank equal to the inherent cycle of the ship,then set a specific roll amplitude.Design 7 types of damper baffles with different openings for U-type passive anti-rolling tank.Establish a three-dimensional U-type anti-rolling tank model with different opening damping dampers by the Ansys ICEM CFD15.0 software.Import the model into Ansys Fluent 15.0,and simulate the roll moment of the anti-rolling tank.Select the best damping plate structure according to Ikeda's data processing method for measuring roll damping in his experiments.(3)Continue to discuss the influence of different liquid depths,different number and position of different baffles,different rolling cycles and different amplitudes on the roll of the tank.After the analysis,some conclusions and recommendations for the use of tanks were obtained.At the end of the paper,the numerical simulation results of the U-type anti-rolling tank based on CFD are given.It can be used to guide the design work of damping structure.The results show that the designed passive U-type anti-rolling tank has a certain anti-rolling effect.Numerical simulations of the forced roll of the water tank with different damper baffle opening,different side tank liquid depth,different baffle number and position,different rolling cycles and different roll amplitude values show that,when the opening degree of the damping baffle is between 40% and 60%,the water tank has the best anti-rolling effect.The change in the level of the side tank has little effect on the anti-rolling effect of the tank.The closer the rolling period is to the natural period of the tank,the greater the moment of damping provided by the resonance of the tank.The roll damping is proportional to the roll amplitude.For a given frequency of forced roll motion,the larger the roll amplitude,the greater the roll damping.