Research On Dynamic Characteristics Of Underwater Supercavitating Projectile Collision And Structure Optimization

Supercavitation drag reduction is a new technology with a very good reduction vibration performance,which not only allows the aircraft to advance underwater at high speed,but also extremely minimizes the resistance of the missile whose value is up to 90%or more.Due to the generation of supercavitation,it will make the aircraft wrapped in the air bubble partly or entirely.When the speed of the aircraft reaches 300?1000m/s in this area,the aircraft will form tail shot phenomenon whose tail pats the bubble wall periodically due to a variety of factors.In this sport environment,the dynamic characteristics of the missile become special due to the impact of the tail shot,which has significant value of the research.In this paper,the self-vibration characteristics and dynamic characteristics of the supercavitated aircraft are studied by using the numerical software such as MATLAB and Workbench,modal modes of body structures and harmonious response are analyzed according to the characteristics of the load force,and optimize the concrete hull structure.The main research contents are as follows:Firstly,the relevant expression of the tail force and velocity is obtained through the hydrodynamic theory knowledge.The different cavitation model and the radius formula are studied to elect the vacuolar model of this paper.The reason and condition of forming tail shot phenomenon are analyzed.As the characteristics of the vibration under coupling are considered,the voyage stage of tail is divided into:the free rotation stage and the collision stage.Then,two voyage stages of the tail shot are further studied.In the free rotation stage,Hamilton variational principle and Von-Karman deformation theory are used to obtain the coupling dynamic control equation,and the lateral vibration frequency expression of the aircraft is obtained by mathematical derivation.And the factors related to the vibration characteristics of the system are studied.in the collision stage,the tail shot two-stage dynamic expression is obtained based on the theory of solving the formula,and the numerical simulation is used to analyze the change of the trailing load and the initial angular velocity which provides the basis for the follow-up work.Finally,the structural response of different shell structures is analyzed based on the variation law of tail shot load,mainly including modal modes and harmonic response analysis,then optimize the concrete shell structure.Different forms of shell structure model are established to calculate their natural frequency values so as to determine the dangerous frequency in the harmonic response analysis.And the different characteristics of the different shell forms are obtained by using Workbench simulation which provides a reference for the future design of the shell;Under the condition of constraints,optimizing the six rib double shell structure and obtaining reasonable shell structure form reduce the shell quality and production cost.