Numerical simulation of multi fin cooperative propulsion and accelerating gliding of a robotic fish

DOI:	10.11809/bqzbgcxb2023.03.024
Keywords:	bionic robotic fish; computational fluid dynamics (CFD); self propelled motion; numerical simulation; hydrodynamics
Abstract:	Aiming at autonomous propulsion of a bionic robotic fish, based on computational fluid dynamics (CFD), this paper realizes a numerical simulation of autonomous propulsion of a bionic robotic fish with separated three degree of freedom pectoral fins and flexible caudal fins, and analyzes the hydrodynamic performance and swimming mechanism of its straight swimming in still water. The bionic robotic fish swims linearly in the flow field through the synergistic action of flexible undulating caudal fins and a pair of rigidly oscillating pectoral fins, in which pectoral fins move through the reconstructed swing curve while caudal fins fluctuate according to specific motion rules. The swimming performance, hydrodynamic performance, velocity vector of the flow field, the pressure cloud map and three dimensional vortex structure of the robotic fish during autonomous propulsion under different duty ratios are analyzed. The results show that the jets and vortices periodically generated by the pectoral and caudal fins jointly promote the autonomous swimming of the robotic fish.Both sides of the pectoral and caudal fins swing with a large pressure difference, and the high pressure vortex sheds backwards to provide thrust in the forward direction.Complex vortex structures are generated around the flow field during the propulsion process, in which the vortices generated by the pectoral fins gradually fall off and merge into the tail vortices, thus enhancing the thrust.The smaller the duty ratio is, the greater the peak value of the thrust coefficient is, and the better the propulsion effect is, but the power consumption also increases.
Issue:	Vol. 44 No. 3 (2023)
Published:	2023-03-28
PDF HTML