ABSTRACT

Dolphins are considered as high-performance swimmers. Their tail fin plays a very important role in their high-speed swimming activity. Based on the structure of the tail fin of dolphins, a bionic dolphin tail fin was designed. The stiffness of the tail fin was controlled by changing the pressure in the air tube, which was embedded in the bionic dolphin tail fin. The propulsive performance of the bionic dolphin tail fin was investigated; the maximum thrust Tmax and minimum thrust Tmin of the bionic dolphin tail fin with lower stiffness were delayed when compared with that of the tail fin with high stiffness. The average thrust with oscillating frequency 2 Hz is nearly 4 times as high as that with oscillating frequency 1 Hz. When the oscillating frequency was 1 Hz, the bionic dolphin tail fins with air tube pressure 1.5 bar and 2.0 bar exhibit a nearly propulsive performance. When the oscillating frequency was 2 Hz, the bionic dolphin tail fin with a high stiffness (P = 2.0 bar) had a higher average thrust.