Research On Aerodynamic Characteristics And Propulsive Mechanism Of Airship Imitating Fish With Oscillating Tail

In recent years,all kinds of civil aerostats of low-and medium-altitude get the nations of the world wide attention and in-depth research,so does floating-platform of stratosphere.The main propulsion method used by this stratosphere airship is propeller at present.This propulsion method is designed under specific altitude and velocity.The propulsion efficiency will largely decrease on the off-design point.However,dolphin and tuna have excellent propulsive performance with high efficiency,high cruising speed,nice maneuverability and low noise,and this kind of propulsive mode(the propulsion by oscillating tail)imitating these aquatic animals has been applied widely in underwater vehicle.Thus,the propulsion mode of the fish is applied to the airship through imitating them.This method can improve the propulsion efficiency and enhance the adaptability of propulsion system.The propulsion characteristics of oscillating tails of airship were studied in this paper.At first the analysis method was built through the Arbitrary Lagrangian-Eulerian Reynolds-Averaged Navier–Stokes Equations,and it contrasts to experimental result to verify the reliability of this method through the CFD simulation of underwater two-dimensional wing.Secondly,the unsteady aerodynamic characteristics of oscillating rigid and flexible single-tail in viscous flow-field are analyzed under the different parameters of oscillating tail,and vertical pattern generated by oscillating tail and corresponding propulsive mechanism are obtained.So do airship imitating fish with oscillating double-tails.At last,we think that the shape of body and tail has a strong impact on aerodynamic characteristics by bionics.And we analyzes the unsteady aerodynamic characteristics of oscillating rigid single-tail in viscous flowfield by CFD under the different parameters of shape.According to above computational results,we get a conclusion that this oscillating tails propulsion method can be used to stratosphere airship as a supplement of the propeller to improve and enhance the performance of the floating platform.