Study On Typical Hydrodynamic Shape Genealogy For Autonomous Underwater Vehicles

Autonomous underwater vehicles(AUVs),which have the characteristics of long-time,continous and autonomous observations,are important means of marine management and resource development.With the development of marine technology,it demands AUVs to have various functions to adapt diversity tasks.Also there is an increasing demands for the quantities of AUVs.The hydrodynamic shape of AUVs affects not only the space utilization,but also the hydrodynamic performance,such as the drag,noise,motion speed,maneuverability and stability.The selection and design of the hydrodynamic shape is a key step to achieve functional goals.Besides,the optimization of hydrodynamic shape,drag and consumption reduction are important ways of energy saving,increasing flight speed and range.Therefore,based on the genealogy theory,efficiency design method for the hydrodynamic shape of AUVs is researched to meet the development requirements of ocean exploration and observation technology.The achievements can provide an important reference for the realization of the rapid and efficient design of the hydrodynamic shape of AUVs for different tasks.Based on the analysis of the hydrodynamic shape features of AUVs,the genealogy theory is applied to the classification of the hydrodynamic shape of AUVs.Based on the principle of hierarchical classification and the similarity and dissimilarity of hydrodynamic performance of different hydrodynamic shapes,the genealogy of the hydrodynamic shape of AUVs is proposed and established based on the contour characteristics.The establishment of the genealogy tree of hydrodynamic shape of AUVs provides a guiding principle for the establishment of a specific mathematical model of the drag coefficient with shape parameters of different hydrodynamic shapes.The CFD method is used to calculate the drag of AUVs.The volume drag coefficient is chosen as the index.Focused on the spherical-shaped hull,the influences of Reynolds number(Re)and length diameter ratio on the drag coefficient are studied.The drag coefficient model of spherical hull is established by using the Matlab analysis tool.The accuracy of the drag coefficient model is verified through the calculation for the drag coefficients of different shape parameters.Focused on the most widely used teardrop-shaped hull,the influences of head and tail shape parameters,length diameter ratio and Re on drag coefficient are studied.The drag coefficient model of the teardrop-shaped hull is established,is verified by comparing with the drag coefficients of the SUBOFF AUV.At the same time,the drag coefficients obtained from the proposed drag model of the present work are compared with those from the traditional empirical formula of drag coefficient.It shows a better accuracy of the proposed model.The influences of the shape parameters(such as head and tail shape parameters,conical tail angle,etc.)of other slender rotor bodies(Such as Myring shape,tail conical,spindle shaped)on the drag coefficient are studied based on the drag model of the teardrop shape.A unified mathematical model of drag coefficient of slender rotor bodies is set up through introducing a correction coefficient.The drags of AUVs with Myring shape,conical tail and spindle are calculated accurately.Focused on the flat-shaped hull,the influences of the width to height ratio on drag coefficient are analyzed based on the study of drag coefficient model of the teardrop shape.The mathematical models of the drag coefficient with ratio of the length to diameter,ratio of width to height and Re are established.The accuracy of the drag coefficient model is verified by the calculation of the drag coefficients of different flat hulls with different parameters.The drag maps of the spherical,teardrop-shape and flat hull are plotted based on the drag coefficient model.The present works provide the basic data for rapid design of different hydrodynamic shape.