Effect of Reynold Number and Angle of Attack on the Hydrodynamic Forces Generated from A Bionic Concave Pectoral Fins

Abstract

Abstract The pectoral fin shape, diameter and speed are the three main parameters for our robotic fish design. The influence of geometrical shape of pectoral fin in labriform mode swimming mechanism is evaluated with the aid of CFD method which is considered as a first step before building the complete design prototype. Two concave shape fins were designed precisely, each of them was attached to a servo motor arm which is in turn connected to a servo motor that is sliding on pair of shafts to work as robot straighter. The two servo motors along with their pectoral fins are placed in lm × 0.5m × 0.5m pool. Different number of angles of attack were tested and the results showed the optimum value is 50°. Further analysis based on Reynold number and its effect on the drag coefficient was investigated carefully. The hydrodynamic forces will be increases with the increasing of angle of attack for all Reynold numbers, which will in turn speed up the overall velocity of the body.