A High-speed Nature Laminar Flow Airfoil and Its Experimental Study in Wind Tunnel with Nonintrusive Measurement Technique

This article deals with an experimental study on the aerodynamic characteristics of a low-drag high-speed nature laminar flow (NLF) airfoil for business airplanes in the TST27 wind tunnel at Delft University of Technology, the Netherlands. In this experiment, in an attempt to reduce the errors of measurement and improve its accuracy in high-speed flight, some nonintrusive measurement techniques, such as the quantitative infrared thermography (IRT), the digital particle imaging velocimetry (PIV), and the shadowgraphy, are applied to obtain precise data about transition locations, separation on trailing edges, and lift/drag characteristics. The experimental results reveal that, in the high-speed flight, small angles of attack are helpful in retaining long laminar flows, preventing the vortex at the trailing edge from moving forward and thus imparting the airfoil and the high-lift and low-drag characteristics. The comparison of the measured results to the calculated ones proves the acceptability of the airfoil and its aerodynamic characteristics satisfying the design requirements.