| China is now a large maritime country with abundant marine resources.Exploration of marine resources has gradually become a hot issue in current engineering practice.The most important exploration method of marine resource is the seismic exploration method at present.Seismic waves are mainly excited by artificial methods.The seismic wave signals will be reflected at the boundary of the seabed medium.We can analyze the submarine structures and detect underground oil and other resources based on the reflected wave signals of seismic recorders.With the country's increased investment in marine development,people have put forward higher requirements for major exploration equipment.Air gun has become the most widely used artificial seismic energy source in offshore resource exploration due to their high stability,safety and environmental protection,high efficiency and high energy,and strong repeatability.The setting of important parameters of the air gun structure,such as air gun aspect ratio,the form,size,angle of the air gun opening and other factors,has affected the performance of the air gun,which becomes a hot topicIn this paper,based on the finite volume method,the numerical simulation results of air gun bubble pulsation are compared with the results of Gilmore's classical compressible spherical bubble pulsation theory.In order to ensure the effectiveness of the algorithm,the numerical simulation results of the air gun bubble pulsation model are compared with the experimental results.The process of air gun bubble pulsation includes the bubble expansion,contraction,secondary pulsation such as near free surface,near rigid boundary,under different gun diameter conditions.The influence of opening size and initial internal pressure on bubble pulsation is analyzed under same gun diameter conditionsThe finite volume method does not need to deal with the mesh topology when the bubble and air gun are coupled or the jet impact and tear of bubble exits.The stability of numerical simulation has been improved.In order to analyze the characteristics of air gun bubble,the influence of the structural design of the air gun bubble pulsation is studied by establishing an axisymmetric model of annular opening air gun bubble,including the volume of the gun body,air gun aspect ratio and angle of the air gun opening.Compare and analyze the bubble pulsation morphology and the pressure characteristics of the flow field around the gun body under different operating conditions,and summarize how to set the structural parameters of air gun to improve the performance of the air gun and obtain a larger initial energy.Finally,a three-dimensional model of four port air gun bubble is established,which is combined with the important parameter setting of the axisymmetric air gun model.The pulsation morphology of the 3D air gun and the pressure characteristics of the flow field are analyzed to provide a reference for the important parameter settings in the structural design of air gun.The purpose of this study is to analyze the shape of bubble pulsations and the pressure characteristics of the flow field around the gun body by establishing a simplified model of the compressible air gun based on the finite volume method.The important parameter settings in the structural design of air gun,including air gun aspect ratio,the form,size,angle of the air gun opening etc.have an important impact on the initial energy of the air gun.The influence of related variables on air gun bubble pulsation is summaried,which provides a reference for the optimization design of the air gun structure. |
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