Investigation on Flow Structure for Low-Aspect Ratio Wing at Critical Reynolds Numbers

• Main Authors: Po-WeiChen, 陳柏暐
• Other Authors: Wei-Cheng Wang
• Format: Others
• Language: en_US
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/20170999235867738248

碩士 === 國立成功大學 === 航空太空工程學系 === 103 === For developing unmanned aerial vehicles (UAVs), micro air vehicles (MAV) and small-scale wind turbine blades, understanding the relationship between the flow structure and aerodynamic performance of NACA series wings is required. Most of the previous studies were focused on two dimensional cases, the clearly investigation of the flow structure of 3D wing still unclear. In this study, the three-dimensional aerodynamics characteristics and flow behaviors of a NACA0003 wing with an aspect ratio of 1 at Reynolds numbers of 75,000 100,000 and 125,000 have been investigated experimentally and numerically. Through the flow visualization, including the smoke and oil flow visualizations, the flow field is presented to identify the leading edge separation, laminar separation bubble and a pair of wing-tip vortex. The three dimensional vortex and Reynolds number have influence on the development of laminar separation bubble. The size of laminar separation bubble decreases along with the spanwise of the wing from the middle section to the tip. This phenomena are more revealing at the higher angles of attack than the lower ones. As the angle of attack increases, the separation bubble which exists on the surface of wing tends to spread in such a way which is no longer perpendicular to the upper surface and is parallel to the chord line. After the length of the separation bubble expand to the chord length of the wing, the formation of bubble expand vertically.