The Fluid-solid Coupling Dynamic Analysis Of The Lifting Flexible Pipe With Different Configurations In The Deep-sea Mining System

Due to the complex and varied marine environment in the poly-metallic nodule mining area in the deep sea,deep-sea mining systems are affected by adverse conditions such as waves,currents,and corrosion.The safety and stability of the deep-sea mining system are the core of engineering design and application.After years of research and practice,China has now adopted a technical program for hydro-collection to mine deep-sea resource minerals.The deep-sea mining system consists of three parts:a water surface platform,an underwater transport system,and a crawler-type mining machine.The underwater transportation system consists of lifting flexible pipe,hard pipe,relay bay and lift pumps.The lifting hose is connected to the ore collector and the relay tank,and is responsible for the task of transporting the slurry collected by the ore head to the relay bay.In this paper,fluid-structure coupling research is conducted on the lifting hoses with different configurations in deep-sea mining systems to provide data support for the safety and stability design of the transportation system.When the mining machine is operating in the seabed,its operating range is determined by the length of the lifting hose;at the same time,the spatial configuration of the lifting hose determines the size of the hose’s drag force on the ore harvester and the slurry conveying.Safety,good space configuration design helps to ensure the stable operation of the ore collector and the safe transportation of minerals.In this paper,the uplifting hose of 100 meters deep in the depth of 1000 meters is taken as the research object,and the configuration of the hose formed at the middle point of the working range is taken as the reference configuration.Based on the finite element theory,the two ends are established.The fluid-structure interaction dynamics model of a fixed-constrained hose under the action of stable external flow(ocean currents)and propeller-driven internal flow,the study of single-arch and double-arch two different configurations of hoses under different effects of internal and external flow The dynamic response.The main results are as follows:In the given single arch and double arch configurations,the calculated six-fold frequency of the wet mode of the double arched configuration hose is smaller than that of the single arch configuration hose;as the internal flow density increases,the two configurations The natural frequency of the hose slowly decreases;the elastic modulus of the hose and the diameter of the hose increase,and the natural frequency of the hose increases significantly;the change of the inflow concentration has a minor influence on the natural frequency of the hose and is negligible;internal flow density,internal When the flow viscosity,the hose diameter and the elastic modulus are changed,the vibration shapes of the two different configurations of single arch and double arch do not change.Under a given outflow,the in-plane displacement and stress of a single-arch structure increase linearly with the increase of inflow velocity,while the displacement and stress of the double-arch configuration increase exponentially;two configuration hoses are in-plane.Displacement and hose stress show periodic changes under the action of internal and external flow.With the increase of internal flow velocity,the fluctuation cycle of the displacement and stress in the plane of the hose decreases and the amplitude increases.The critical velocity of the single-arch structure is about 10m/s,while the critical velocity of the double-arch structure is about 8m/s.When the inlet velocity of the two type of configurations are approaches,the mechanical performance of the single arch is better than the double arch configurations.