On the use of bio-inspired aerofoils for unmanned aerial vehicles

• Main Author: Lim, Chuan Yuan.
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/53450
• Institution: Nanyang Technological University

This report is a follow-up study on the aerodynamic performances of unconventional aerofoils, particularly of those shaped to that of the dragonfly wings. In this study, numerical simulations were carried out to gather lift and drag data of the NACA 0010, Corrugated A and Corrugated B aerofoils. The conditions applied in the simulations were similar to that of the experimental setup done by Chan[1]. The dimensionless Reynolds number used was 14,000, while the aerofoils were pitched at angles-of-attack from 0˚ to 20˚, at 5˚ intervals. The data collected from the numerical simulations were then compared with previous experimental findings; the flow behaviour of the corrugated aerofoils were once again analysed and were found to agree well with the flow visualisation results from Chan [1]. However, the lift and drag values obtained for the three aerofoils in study could not better contribute to an understanding of the corrugated aerofoils. This is essentially due to the inability of determining a typical trend for the values generated by the simulations. Such a finding was attributed to the insufficiency of the numerical turbulence model applied within this study's approach. Nonetheless, a qualitative analysis was carried out based on the values obtained. They showed that the corrugated aerofoils, particularly corrugated B, were indeed capable of better aerodynamic performance at a low Reynolds number flow. Corrugated B aerofoil was also selected in consideration to enhance its flight performance, as it has been found to be the best performing aerofoil among the three at study. A control surface was added onto this wing through a modification made at the rear section of the trailing-edge hump. This provided for a plain flap that was capable of undergoing downward deflections from 5˚ to 15˚, at 5˚ intervals. Experiments were then carried out to determine the effects of this added flap. Particle-streak photography and particle image velocimetry techniques were employed in the study. The results showed that the flap was unable to augment the lifting capabilities of the aerofoil. Instead, flow separation events were initiated with the onset of a flap deflection, while the wake grew larger with each successive flap deflection. It was therefore determined that this flap would only be useful for angles-of-attack from 0˚ to 10˚, with a flap deflection of no more than 5˚. The results also gave a clear indication on the importance of the trailing-edge hump in providing for Corrugated B aerofoil's exceptional aerodynamic performances and as such, should not be disturbed. However, it does pave a way for further studies, such as having the flap executing upward deflections or considering other types of flap designs.