Research On The Sloshing In Tank And Its Effects On The Global Motions Of Ship

Liquid sloshing in tank is excited by the global motions of ship, meanwhile the loads induced by sloshing act on the ship reversely, and affect the global motions of ship. The coupled problems between tank sloshing and ship motion are attracting more attentions with the increase of ship size and the improvement of operation efficiency and security of ship. To solve them, it need to pay attention to three aspects:ship motion prediction, tank sloshing simulation, coupling motion of sloshing and ship.In this paper, the ship motion and tank sloshing are solved separately, after some intense research on both of them, the equation of ship motion considering the effects of tank sloshing is established in frequency domain. Based on3d potential flow theory and radiation/diffraction theory, the theories of using ANSYS AQWA software to calculate hydrodynamics of ship are derivate, which is the theoretical basis of ship motion prediction, it also applies theoretical basis of tank harmonic oscillation displacements’choosing. Based on VOF method, using the ANSYS FLUENT software to simulate tank sloshing is executed; by contrasting the sloshing load results of theoretical calculation, numerical simulation and model test, the reliability of numerical simulation method is demonstrated. Then the sloshing force(moment) of a2d-tank is studied by the numerical simulation method:proposing the data processing method of sloshing force(moment) basing on first-order Fourier fitting and demonstrating it; the intense research about the rules of variation of sloshing force(moment) and the phase difference between sloshing force(moment) and tank oscillation displacement with the change of some relevant parameters is carried on. Furthermore, the research of sloshing force(moment) illustrates the functional relationship of one-to-one correspondence between the sloshing force(moment) amplitude and phase difference and the oscillation frequency, which provide a basis for the hydrodynamic calculation of tank sloshing. Combining the method of the hydrodynamic calculation of tank sloshing to the method of ship motion’s calculation in frequency domain, the equation of ship motion considering the effects of tank sloshing is established; then demonstrating it by calculating the motion of a ship with single tank. The contrasting results of ship motions with different tank filling levels indicate:the ship resonance frequency is to be shifted because of the existing of tank sloshing; and the effects are different with different tank filling levels.