Stereo vision investigation of elastic flap kinematics in separated flow. (October 2022)

• Record Type: Journal Article
• Authors: Reiswich, Artur; Finster, Max; Heinrich, Martin; Schwarze, Rüdiger
• Is Part Of: Journal of fluids and structures. Volume 114(2022)
• Publication Date: 2022-10
• Subjects: Low Re airfoil -- Flow separation -- Flexible flaps -- Lift increase -- Flap kinematics -- Stereo vision technique; Fluid-structure interaction -- Periodicals; Fluid mechanics -- Periodicals; Structural dynamics -- Periodicals; Structural analysis (Engineering) -- Periodicals; 620.106
• DOI: 10.1016/j.jfluidstructs.2022.103711
• Languages: English
• ISSNs: 0889-9746

Abstract

Abstract: Self-adaptive and flexible flaps adopted to low Reynolds number airfoils are able to improve the airfoil performance near to and in the stall regime. In the present study, experiments are carried out in a wind tunnel using a NACA0020 airfoil for a Reynolds number of 2 × 1 0 5 . Passive, flexible flap rows are attached to the leading and also the trailing edge of the airfoil. Its angle of attack is adjusted to 2 5 ∘ to achieve flow separation. A previous study has shown that the performance of the airfoil with flaps is much better in comparison with the flapless airfoil. In order to understand details of the underlying mechanism, the present study investigates the time-resolved behavior of the flaps. Therefore, the stereo vision technique is applied to record the edge of selected flaps. Afterwards, flap positions are reconstructed for each recorded image pair. With this information, the velocity and the frequency of the flap edge is derived. The analysis of the flap kinematics reveals among others a non-harmonic mean oscillatory behavior of the flap with slow upward and fast downward motion.