SHAPE DESIGN AND FLOW FIELD CHARACTERISTICS OF A ROBOTIC FISH IMITATING THE HEAD OF A HAMMERHEAD

In recent years, the exploitation and utilization of marine resources have risen to a social research highlight. In this context, domestic and overseas scholars work to promote the study on many aspects of underwater vehicles. As an important part of the research, the hull shape design of the underwater vehicles has direct relation to their underwater hydrodynamic characteristics. A variety of fishes in nature have attracted extensive attention from researchers for their good hydraulic resistance performance. In order to design a hull shape of underwater vehicle with good hydrodynamic characteristics, this paper focuses on the study of Sphyrna with a winglike head which enables their nimble swimming in oceans. This paper took Sphyrna as the bionic object, analyzed the water resistance reduction effects of three species of Sphyrna by establishing models, selected the biological shape characteristics of hammerhead shark as the reference to design the characteristic outline curve of the hull. Furthermore, a kind of hull shape of underwater vehicle has been designed according to engineering practice. Ansys Mosaic Technology was applied to establish a 3D structured flow field mesh model, and a Fluent simulation of the model followed. Apart from that, the author compared it with the shapes of common wing-shaped hulls and rotational underwater vehicles, focusing on its resistance performance. The result of a simulation analysis shows that the Sphyrna bionic model demonstrates better hydrodynamic characteristics in a stationary flow field than those of the two kinds of common underwater vehicles. Additionally, this paper also designed a comparative experiment to explore the characteristics of the flow field around the Sphyrna bionic model, which is of great guiding significance for the study on reducing the interference of the vehicles to the surrounding flow field and improving the stealthiness of the vehicles, and also provides a new direction for the design of underwater vehicles.