Abstract
We experimentally investigate the effect of material, length, and spacing of trailing-edge extensions on controlling the flow over an airfoil based on our recent experimental work. Force measurements and flow field quantifications were carried out to investigate the aerodynamic performance and flow structures in the wake of an airfoil and, thus, to reveal differences in control effectiveness and mechanisms. Moreover, multi-scale proper orthogonal decomposition and spectral proper orthogonal decomposition are employed to extract coherent flow structures in the flow field. The results indicate that the owl feather can improve the aerodynamic performance, while artificial materials lead to decreased lift-to-drag ratio. However, nylon has optimal adaptability and robustness in controlling turbulent fluctuations, including Reynolds stress and turbulent kinetic energy at different angles of attack (AOAs). The length sensitivity is highly associated with the AOA, i.e., the optimal length increases with the increase in AOA. In addition, the spacing sensitivity correlates with the Reynolds number (Re), i.e., the optimal spacing decreases with higher Re at high AOA. These differences root in the competition effect between the increasing adverse pressure gradient and the interference on regular vortex shedding. It is concluded that nylon with mediate length (L = 0.2D) and relatively large spacing (S = 0.5B) is recommended for wake control and noise attenuation of the S833 airfoil.
Funder
National Natural Science Foundation of China
Fundamental Research Funds for the Central Universities
Subject
Condensed Matter Physics,Fluid Flow and Transfer Processes,Mechanics of Materials,Computational Mechanics,Mechanical Engineering
Cited by
3 articles.
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