Construction And Experimental Research On Hydrodynamic Model Of Oil Boom In Mountainous Rivers

In recent years,with the rapid development of the inland shipping industry,frequent oil spill accidents have brought major safety hazards.To reduce the losses caused by oil spill accidents,the use of oil booms to intercept oil slicks on the water surface has become an important method of the emergency response to oil spill accidents.Most of the research on oil booms focuses on the flow conditions of the interaction of waves and currents in the marine environment,while the rivers in mountainous areas are dominated by directional jets.To improve the oil spill interception effect of oil booms in mountainous rivers,by use of numerical simulation and physical model experiments,according to the flow conditions of mountainous rivers,the influence of oil boom design parameters on its performance under the action of different water flows were discussed to guide the development of oil booms suitable for mountainous rivers.(1)Based on the Ansys-Fluent numerical simulation software,a two-dimensional numerical model of the oil boom conforming to the flow conditions of mountainous rivers was constructed.Through independent verification,the grid size of the numerical model in this paper was determined to be 0.005 m,and the time step was 0.005 s;the parameters such as the center of gravity position and the moment of inertia of the oil boom were determined by use of the numerical simulation hydrodynamic experiment;through the validity verification,the motion state of the oil boom under the condition of steady flow was successfully simulated,and the numerical value compared with the physical model experiment The relative error of the simulation is 5%.(2)Aiming at the motion response characteristics of the oil boom,using the numerical simulation method,the water flow velocity and the parameters of the oil boom in the section from Jinghong to Boundary 243 of the Lancang-Mekong River are set according to the "Oil Boom" GBJT/T565-2017 specification.The parameters of the numerical model are numerically simulated.Results show that the pitch response range of the oil boom is affected more by the water flow with increase of its buoyant weight ratio in mountainous river conditions.The draft of the long skirt oil boom decreases more obviously when the buoyancy-to-weight ratio of the oil boom is smaller and the draft is larger with increase of the water velocity.For the effective freeboard height,the larger the buoyant weight ratio of the oil boom,the less affected by the impact of the freeboard height by the water flow;The decrease in shipboard height is also smaller.It can be seen that in order to make the oil boom have better performance under the conditions of mountainous rivers,it needs to have the characteristics of a small buoyancy-to-weight ratio,moderate skirt length,and large enough float diameter.(3)Based on numerical simulation experiments,physical model experiments are conducted to study the effects of buoyant weight ratio,skirt length,and float diameter on the response range of boom pitch,effective draft,and effective freeboard height under various water velocity conditions.Furthermore,the influence of boom stiffness on the motion response and motion response state of the boom at high flow rates is further investigated.Results show that : The greater the buoyant weight ratio of the oil boom,the more significant the pitch response range is affected by the flow velocity;The larger the skirt length of the oil boom,the larger the pitch response range,and the large buoyant weight ratio(B/W=4)of the oil boom,its pitch response increases more than that of the oil boom with small buoyant weight ratio(B/W=2);The oil boom with larger float diameter has a relatively smaller pitch response range.The smaller the buoyant weight ratio of the oil boom,the greater its effective draft;The larger the length of the oil boom skirt,the greater the effective draft;When the diameter of the float is small(D=0.05m),the draft decreases substantially as the water velocity increases.The greater the buoyant weight ratio of the oil boom,the greater the effective freeboard height;The larger the skirt length of the oil boom,the smaller the decrease in the effective freeboard height with the increase of water velocity;The effective freeboard height of the long skirt oil boom with large buoyant weight ratio(B/W=4,L=0.20m)increases when the flow velocity V≥0.20m/s.When the buoyant weight ratio B/W=4,the difference between the rigid oil boom and the flexible oil boom is small;When the buoyant weight ratio B/W=2,under the same flow rate,the rigid oil boom The pitch response range of the rigid oil boom is smaller than that of the flexible oil boom,and the draft of the rigid oil boom is relatively less affected by the water velocity.Under the condition of high flow velocity(V=0.54m/s),the oil boom with buoyant weight ratio B/W=2 is almost submerged,while the oil boom with buoyant weight ratio B/W=4shows a significant uplift posture.The results obtained from physical model experiments and numerical simulations corroborate each other,and the motion response performance of rigid oil boom is better under the condition of high flow velocity.