Aerodynamics of unconventional airfoils

• Main Author: Tee, Kok Heng.
• Other Authors: Jorg Uwe Schluter
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Aeronautical engineering::Aerodynamics
• Online Access: http://hdl.handle.net/10356/39843
• Institution: Nanyang Technological University

This project investigated the lift characteristics of high lift low Reynolds number (Re) airfoil S1223 under low Re flow regime for Micro Air Vehicle (MAV) applications through numerical methods using FLUENT and experimentally via water tunnel aerodynamic testing. The project also explored the effects of a flap addition to the airfoil. The airfoil S1223 was reported to achieve a Cl,max of approximately 2.2 under flow conditions where Re = 20,000. The first part of the project validated the compatibility of the Spalart-Allmaras (SA) turbulent model and the K-Epsilon (K-ε) turbulent model at Re = 200,000, with the latter model matching the known experimental data to a large extent in terms of the stall angle and the Cl,max achieved. The SA and K-ε models achieved a Cl,max of 1.9863 and 2.0355 respectively. The second part of the project revealed that at Re = 30,000, the FLUENT analysis using the laminar and SA models exhibited high correlation in their lift characteristics. The K-ε model gave similar results except for angle of attack (AoA) ranging from 8 to 23 degrees. Unfortunately, the water tunnel experiments yielded inconsistent results and no comparison was viable. Nevertheless, similar observations were made in both laminar and SA models whereby the separation point shifted towards the leading edge and the amount of backflow increased significantly after stall. The last part of the project proved the addition of flap to the airfoil increased the lift generated significantly, with the laminar and SA models giving a rise of up to 40-70% and 30-50% respectively. The low-pressure region on the upper surface was responsible for creating the additional lift. However, the locations of the low-pressure region in the two models were completely different. A low-pressure region developed at the leading edge in the SA model whereas an additional low-pressure region was formed at the trailing edge on the upper surface in the laminar model.