Studies On Shock Response For Surface Ship Under The Pressure Of Air Gun

Bubble dynamics is a classical topic of fluid dynamics.Recently,researchers pay more attention to some new phenomenons such as drag reduction,noise reduction and so on.From the beginning of the 60's of last century,air gun has gradually become a necessary equipment for seabed resource exploration due to the environmental protection,stable characteristics.For military use,the explosive load is instead by the airgun load is used in the real warship experiment.This paper firstly simplified the air gun model,then the domestic and overseas researching progresses are summarized from the theoretical,experimental and numerical aspects.The methods of airgun bubble are mostly based on the spherical bubble equation,and on the other hand boundary element method shows more advantage in the bubble dynamics with the more fast calculation speed of computer technology.Therefore,under the assumption of the incompressible potential flow theory,the paper developped the axisymmetric boundary element bubble model and 3D boundary element bubble model.This paper established a complete airgun bubble model by improving the BEM bubble model.Firstly,modifying the state equation of BEM model by considering the effect of air gun temperature and the outlet of the airgun,one gun BEM model is established.Secondly,The 3D BEM bubble merging model(coherent gun model)is develped,the bubble merging process is studied by the technology called "suture",and the distance between bubbles how to affect fusion and jet is discussed.In order to obtain the dynamic characteristics of the airgun bubble,in this paper,the axisymmetric BEM model is established to simulate the experiment: a spark bubble between two cylinders,the agreement of which is good.It will provide the reference about the study of the effect between arigun body and pressure wavelet.Besides due to the gravity and the interactions between the bubbles would lead to the complex bubble jet and merging,and it's too difficult to deal with the mesh of the bubble array by using the "suture" technology,considering this,the bubble array model is established by the bubble equivalent algorithm based on the bubble energy equation and the far field pressure equation.Finally,the computer memory consumption and computation time is unacceptable because of the too much mesh,the subarray model is established,and another respectively two parallel methods are produced with Matlab and Fortran,the result of acceleration is good.Finally,in order to study shock environment of ship damaged by the high-pressure air gun(air gun missile),the interaction between airgun bubble and the rigid cylindrical shell was studied by the 3D BEM.Besides,ship whipping under airgun wavelet is simulated by the ABAQUS structural-acoustic interaction method.Besides,the equivalent between arigun load and the explosive load is studied in the warship experient.