| The oil leakage and environmental pollution caused by the grounding or collision of the ship in the course of navigation will have a great impact on the economy,environment and people’s lives.It is of great significance to master the leakage characteristics of the damaged oil tanker for the design of liquid carrier ships,maritime shipping safety and marine environmental protection.In this thesis,based on the theory of viscous fluid dynamics,a RANS equation based on the SST k-ω turbulence model is established to simulate oil-water flow.The flow field is discretized by finite volume method,oil-water interface is captured by VOF method,and oil tank motion is captured by overlapping grid method.With the help of STAR-CCM+ software platform,the leakage/water inflow process of the moving oil tank was numerically simulated.The main research contents and conclusions are as follows:(1)A numerical model for the leakage / water inflow and sloshing of two-dimensional oil tank in calm water under forced swaying motion or rolling motion was established.The influence of the size and location of the damaged hole on the leakage characteristics was studied and the relationship between the oil tank motion and the mass flow at the damaged hole was analyzed.The results show that:(1)the leakage time of the damaged hole in the side is longer than that of the damaged hole in the bottom;(2)the mass flow fluctuation at the damaged hole is mainly affected by gravity,oil tank motion and natural frequency of liquid sloshing in oil tank;(3)the larger the damaged hole size is,the earlier the leakage and water inflow are stable;(4)the greater the linear velocity of the damaged hole in the oil tank is,the greater the leakage and inflow are.(2)The leakage / inflow model of damaged oil tank in calm water is established when it is in free roll attenuation motion.The effects of liquid loading rate,hole position,hole size and initial inclination angle on leakage characteristics were studied.The conclusion shows that:(1)the smaller the gravity is,the more the leakage characteristics of the oil tank will be affected by the movement of the oil tank;(2)the damaged hole in the side is more susceptible to rolling motion than the damaged hole in the bottom;(3)The increase in the size of the oil tank perforation leads to an increase in the mass loss of the oil tank,and the change in the inertia moment is more obvious,which affects the movement of the oil tank jointly with the oil-water flow at the perforation;(4)The leakage and water inflow at the danaged hole increase the rolling damping and reduce the rolling motion of the oil tank.(3)A three-dimensional numerical model for the leakage / inflow of damaged oil tanks in waves is established.The effects of wave height,wavelength and wave direction on the motion characteristics and leakage characteristics of oil tanks are studied.The difference between the damaged hole in the side and the damaged hole in the bottom under the influence of waves is analyzed.The results show that:(1)under the action of gravity,due to the loss of oil leakage power caused by the movement of oil tank,the greater the movement amplitude of oil tank is,the slower the leakage rate is;under wave action,the leakage velocity,inlet velocity and leakage rate increase with the increase of wave height;(2)the change of wavelength leads to the difference of the movement amplitude of the oil tank;the coupling of the damaged hole position and the movement direction can significantly affect the leakage.When the damaged hole in the bottom,the fluctuation of mass flow at the damaged hole is related to the heave motion,and the greater the heave amplitude,the faster the leakage speed and the inflow speed,and the greater the leakage volume;(3)when the incident wave is the same,the mass flow at the side hole is related to rolling motion,and the leakage and inflow of the damaged hole in the side are larger,and the rolling motion amplitude is larger,among which the rolling amplitude is the largest under the wave-front condition;because the wave-front condition is affected by wave propagation,and the water inflow occurs earlier than the other conditions,and the leakage and water inflow are the largest. |
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