Experimental research on a bionic propulsor with double tail-fins

To understand the causes of forebody swing in robotic fish with a single tailfin,changes of thrust and transverse force coefficients of bionic tailfins were analyzed.A robotic fish with two tailfins was designed to simulate the tail swing of Tunny,and was used in a SWATH ship.A new experimental platform for a propulsor with double tailfins was developed.Next,the wake of the double tailfin propulsor was compared with that of highly efficient fishes.The relationship between the speed and resistance of a robotic fish and its thrust under bollard conditions was tested experimentally.The experimental evidence on double tail-fin propulsion reveals that the swing frequency and amplitude of the tail-fin imposes more influence on the performance of double tailfin propulsion,especially on the amplitude.Lunate tailfins are more efficient than the rectangle type.Double tail-fin propulsion not only makes full use of bionic propulsion,it overcomes the problems of swing in the forebody and the low efficiency of single tailfins.