Oil Droplet Size Distribution In Underwaterpipeline Leakage

In the past decade,the exploration and production of offshore petroleum and gas have been increased significantly with the increase of the laid oil and gas pipelines in the sea.However,the leakage rate of oil and gas is also rising,which can cause the serious harm of deep sea oil and gas pipeline leakage.This great disservice is far greater than that of the sea oil spill.The seabed oil spill has had a serious impact and harm on marine life and coastal cities.Most of existing studies on oil spill are limited to sea oil spill,the study of seabed oil spill which is paid more attention to the oil spill with a large flow rate,and the leakage from a small hole is rarely involved.In this paper,the oil droplet size distribution of micro-hole leakage in underwater pipeline is studied experimentally and theoretically,and the plume morphology in different leakage conditions is also compared and analyzed.The concrete work is as follows:1.The experiment on leakage from a small hole on the underwater pipe was carried out.The oil droplet sizes as well as their distributions were measured at different leakage flow rates and leaking gap sizes.The experimental results show that the leakage amount has a great influence on the size of the oil droplets.The oil droplets are mainly affected by the surface tension,and the oil droplets that rely on buoyancy to counteract their surface tension.With the increase of the leakage,the oil spill in the flow of the initial kinetic energy and oil droplets under the action of the surface can be broken into a large number of small oil droplets,and the oil droplets in the water to overcome their own surface tension to transfer kinetic energy into surface energy.The size of the drops gradually decreases,and the surface area of the oil droplets is increasing to obtain more surface energy.With the increase of the leakage amount,the oil droplet obtains a larger outflow velocity and formers a strong turbulence at the leak hole,which leads to the oil droplets are broken down into smaller oil droplets under turbulence.When the turbulence intensity increases to a certain extent,the oil droplets tend to become atomized.2.The influence of leakage and leakage aperture on outflow is studied.The stress condition of underwater oil droplets is analyzed,and it is verified that the oil droplet size estimation formula can be used in the case of the low Reynolds number,but this formula is not applicable in the case of a larger Reynolds number.In this paper,the overflow shape of the oil spill in the underwater level is studied and compared with the vertical release.When the oil is released vertically,the buoyancy has the same direction as plume movement,and this will make the plume move more quickly.When the oil was released horizontally,the buoyancy is perpendicular to the initial momentum.Under this condition,the plume will gradually bend upward.When the horizontal initial momentum is consumed,the plume is completely transformed into a vertical ascending motion.Therefore,the vertical movement of the plume will be slower and the width of the plume will be faster and wider.3.The theoretical model of oil droplet size distribution is established by using the maximum entropy method,and the constraint equations were obtained from the mass and the energy conservations of oil.The theoretical model is solved by the numerical technique,and the comparison between theoretical and experimental results shows that the prediction results are in good agreement with the experimental data,which shows that the present model can roughly demonstrate the evolution of the drop size.the present work provides important data on droplet size for accurate prediction on oil droplet movement by the reach of underwater pore oil spill.