Experimental Research Of A Tail-fin Propulsive System

Recently, Underwater Vehicle (UV) technology has been drawing increasing interests and widely applied in the fields of exploitation of the sea natural resource, reconnaissance and military science. It is also believed that exploring the sea resource has provided a useful and valuable platform for the research and developments of UV. Thus, in order to overcome the disadvantages of conventional UV, and improve better propulsion and control systems, much attention has been paid on bionic technology, a significant branch of the UV research.Fish swimming posses the advantageous natures of fast speed, high efficiency, high flexibility as well as low noise. Hence, applying fish swimming configuration to UV to replace conventional screw propeller and rudder system should be of a great importance issue. This paper mainly focused on designing an propulsive device and setup in analogy to bionic tail fin so as to investigate the hydraulic dynamics of the tail fin.Firstly, on the basis of the feature of fish swimming, a suit of mechanical setup with two joints and one tail fin was designed. Thereafter, the design concepts and the propulsive device of the bionic tail fin propulsive system were demonstrated. Secondly, according to the inherent characteristics of rotation axis, the displacement and degree for the swing of the tail fin could be calculated and estimated from the rotating angles. Finally, the movement modes of real tail fin could be controlled and simulated via the procedures of setting parameters according to the given angles of the propulsive device, followed by running the programs after these parameters were input into the system.Following the simulations of serious movements, corresponding signals of the forces were received through data collecting system. Therefore, several parameters in terms of propulsion efficiency, propulsion coefficient, lateral force coefficient and torque coefficient could be obtained via computations of instant force by using the formula conducted. Additionally, the movements of the bionic tail fin propulsive system could be optimized by the comparisons of the propulsion efficiency, propulsion coefficient, lateral force coefficient and torque coefficient at different conditions (i.e. movement parameters). Last, error analysis was carried out to correct the movement curves and obtain more precise experimental data and results.