Unsteady aerodynamics of flapping bionic eagle wings in forward flight: An experimental and numerical study

Abstract

The aerodynamic performance of fabricated eagle wing with the corrugated trailing edge was investigated experimentally and numerically in this study. In this respect, wings were designed by imitating the bionic eagle wing and fabricated using a 3D printer. Tests on the wings were performed in a wind tunnel for different bending deflection angles, flapping frequencies, angles of attack, and forward flight velocities. As the key parameters, lift and thrust forces, lift-to-drag and input power were compared between eagle wing and simplified wing. The results revealed that the eagle wing with the corrugated trailing edge led the lift force to be improved by 14% on average compared to the simplified wing, with the largest improvement of 45%. Further, the thrust force of a eagle wing was greater than that of the simplified wing (up to 21%). Also, the input power of the simplified wing mechanism was greater than that of the eagle wing. Numerical simulations were performed to study flow physics. After validating the numerical results against the experimental results, the lift and thrust force, lift-to-drag, pressure contours and vortex were compared between the eagle and simplified wings. The results of the numerical simulation revealed that lift-to-drag increased with for eagle wing with the corrugated trailing edge of eagle wing. the pressure difference between the upper and lower surfaces of the eagle wing was larger than that of the simplified wing; therefore, the lift force produced by the eagle wing was larger than that of the simplified wing.