Analysis Of Flow Field And Ship Collision Of Bridge Piers With Collision Avoidance Floating Boxes

The regulation of inland waterways has improved the navigation level of the Yangtze River section,and the navigation tonnage continues to increase,increasing the probability of ship collision with bridges.The problem of ship collision with bridge is a typical fluid structure coupling problem.When a ship sails in a river basin,it will have an impact on the surrounding flow field.When a ship collides with structures such as bridge piers,the ship will have a strong motion response in an instant.In addition,during the collision process,the flow field affected by the ship will in turn affect the process of ship collision with bridge,affecting both the movement and deformation of the ship.The interaction between the two forms a fluid solid interaction between the ship bridge structure and the surrounding flow field.In previous studies,due to limitations in computational power and software platforms,the added mass coefficient method is commonly used to express the impact of fluid in ship bridge collision problems,which is helpful for calculating the maximum impact force generated during the collision process and can quickly solve the impact force.However,the added mass method does not take into account the specific impact of the flow field on the ship,and has limitations for fully reflecting the entire collision process,Therefore,the fluid-structure coupling method has more advantages in the study of ship bridge collision problems.Based on ABAQUS and STAR-CCM+,a joint simulation fluid-structure coupling method is used to study the ship bridge collision problem.ABAQUS is used to solve the solid domain,and STAR-CCM+ is used to solve the fluid domain.The impact of the ship pier structure and the fluid domain on the collision process can be considered simultaneously.Based on the navigation conditions and relevant data of the Yangtze River Basin(Chongqing section),this thesis selects airworthiness as the collision vessel,establishes a ship collision bridge pier model based on the added mass method in ABAQUS,and establishes a joint simulation ship collision bridge pier model based on the fluid structure coupling method in ABAQUS and STAR-CCM+.This thesis studies the dynamic response and hydrodynamic characteristics of the ship bridge during ship collision with bridge piers from different angles and speeds,and then adds an anti-collision buoyancy tank to explore the impact of the buoyancy tank on the impact results.The main research contents of this article are as follows:(1)The Niujiaotuo Jialing River Bridge in Chongqing was selected for the study of ship bridge collision,and the ship bridge collision model was established in ABAQUS to explore the dynamic response of the ship and the damage of the ship during the collision process.The simulation results were compared with the calculation results of the specifications and empirical formulas,so as to verify the feasibility of ABAQUS in studying the problem of ship bridge collision;Establish a naked hull self-propelled model of the ship type in STAR-CCM+,compare the resistance values obtained by STARCCM+with experimental values,and compare the impact of different grid numbers on the calculation results to verify the reliability and grid independence of STAR-CCM+in hydrodynamic simulation.(2)Demonstrate the type of anti-collision buoyancy tank,and finally determine the parameters and dimensions of the rubber anti-collision buoyancy tank used in this article.Then,based on this anti-collision buoyancy tank,establish a pier simulation model for ship collision with anti-collision buoyancy tank under the fluid-structure coupling method in ABAQUS and STAR-CCM+.Briefly describe the technical difficulties of joint simulation setup,and then conduct ship collision pier simulation calculations with different additional mass coefficients based on ABAQUS,and conduct ship collision under the same working conditions based on STAR-CCM+ and ABAQUS The fluidstructure coupling method is used to simulate the collision of bridge piers,explore the relationship between the added mass coefficient and the peak value of the collision force,analyze the ship damage deformation and collision stress time-history curves under the two methods,and compare the two methods to explore the similarities and differences between the two methods and the impact of fluid on the collision results during the collision process.(3)After verifying the similarities and differences between the added mass method and the fluid solid coupling method,ABAQUS and STAR-CCM+ were used to jointly simulate the fluid solid coupling method to study the ship bridge collision.In the case of a frontal collision,set three sets of velocities(v=2,4,6),analyze the impact stress curves and stress strain nephogram at different speeds,analyze the flow field and wave height under different working conditions,and explore the stress strain effect and hydrodynamic characteristics of ship speed on the impact results;Set four groups of collision angles at maximum speed v=6m/s(α= 45 °,60 °,75 °,90 °),explore the impact of ship impact angle on the stress strain and hydrodynamic characteristics of the impact results.(4)To explore the impact of anti-collision buoyancy tanks on the impact results,based on the conditions listed in(3),select the conditions of ship collision with bridge piers at different angles at maximum speed,install a anti-collision buoyancy tank with a thickness of 20 cm on the bridge piers,explore the changes in the impact stress curve between the ship pier and the pontoon pier after the installation of the anti-collision buoyancy tank,and compare the maximum impact stress changes on the bridge piers after the installation of the anti-collision buoyancy tank,Compare the changes in flow field and wave height after installing the anti-collision buoyancy tank to obtain the stress strain effect and hydrodynamic characteristics of the impact results after installing the anticollision buoyancy tank.(5)On the basis of(4),three sets of anti-collision buoyancy tanks with different sizes(thickness=20cm,25 cm,30cm)are set up to compare the maximum impact stress changes borne by the bridge piers under different sizes of anti-collision buoyancy tanks,compare the differences in the impact stress curves between the buoyancy tanks and the bridge piers under different sizes,and compare the flow field and wave height conditions to explore the impact of the size of the anti-collision buoyancy tank on the impact results,Combining economy and protection to make an appropriate choice for the size of the collision avoidance buoyancy tank.