Research On Characteristics Of Underwater Gas Jet And Its Impact Damage On Marine Structure

The problem of underwater gas jet exists in the field of naval architecture and ocean engineering widely,such as the marine tank which is used to cool the high temperature and high pressure gas,there is a complex phenomenon of high pressure gas jet inside,which belongs to a strongly nonlinear transient changing process,it’s a kind of extremely complex two-phase flow problem,accompanied by the impact to the structure of cabin from the jet load at the same time,which increase the difficulty to research the problem.Therefore,based on both numerical and experiment method,the paper studies the phenomenon,the mechanical nature as well as the impact effect on the boundary of underwater gas jet problem,which has important engineering significance.Firstly,the paper builds the numerical model of underwater gas jet dynamics.The VOF multiphase flow model is used to track the jet interface,modified RNG turbulence model and gas-liquid transformation model for high temperature steam is used to simulate the process.By the contrast of simulation and experiment of the pressure characteristics of vehicle’s tail gas jet,the validity of the numerical method in this paper is verified.Secondly,the paper builds the two-dimensional axisymmetric model of jet flow field and studies the numerical characteristics of jet field basicly in the process of the jet,for the important physical quantities such as jet form and pressure or velocity distribution,the paper studies the influence of different inlet pressure conditions on the physical characteristics of jet flow field,besides,under the condition of same inlet pressure,the paper analyzed the two cases of considering the conversion between high temperature gas and water and not considering the conversion by contrast,as a result,the influence of temperature of gas jet is concluded。Thirdly,the paper use self-designed experimental apparatus of underwater gas jet to further study the problem based on experiment method.A variety of connection forms of inlet pipe are designed to study of the formation and development laws of Jet flow field,and the free surface splash phenomenon caused by the jet,it makes up for the inadequacy of the numerical method to simulate all kinds of phenomena.At last,the paper gets a connection form that can lower the jet impact effect through the analysis,which will provide experimental reference for the study of gas jet impact effect in tank.Finally,based on the engineering application background of the underwater gas jet,the paper numerically simulate gas jet in tank with a given connection form of pipe,it analyze the high temperature and high pressure gas jet flow field inside,then the impact load of each tank wall is get.The finite element software is used to calculate the structural response,it obtains the corresponding laws of jet impact effect.The paper discusses the influence of jet pipe structure form on the impact load,finally the connection form of pipe inside tank is optimized to provide valuable reference for engineering.