Unsteady flow over flexible wings at different low Reynolds numbers

Abstract

Abstract. In this study, unsteady flow around flexible membrane wing which had aspect ratio of 1 (AR=1) was investigated experimentally at various Reynolds numbers (Re = 25000 and Re = 50000). Smoke-wire technique for flow visualization over the flexible membrane wing was utilized in the experiments. Digital Image Correlation system (DIC) was used for measuring deformation of AR = 1 flexible membrane wing. Instantaneous deformation measurements of membrane wing were combined with the flow field measurements. In low aspect ratio flexible membrane wings, unsteadiness includes tip vortices and vortex shedding, and the combination of tip vortices. In these types of wings, complex unsteady deformations occurred due to vortex shedding. The results showed that the increasing angle of attack results in increase of membrane deformation. Moreover, it was concluded that analysis of the instantaneous deformation revealed chordwise and spanwise, modes which were due to the shedding of leading-edge vortices as well as tip vortices. Consequently, vibrational mode decreased and maximum standard deviation location approached to the trailing edge by reason of increasing angle of attack.

Traditional and New Types of Passive Flow Control Techniques to Pave the Way for High Maneuverability and Low Structural Weight for UAVs and MAVs

“…instant deformation found out spanwise and chordwise, which were due to the shedding of leading-edge vortices' farther tip vortices [77].…”

Comparative Study Aerodynamics Effects of Wingtip Fence Winglet on Fix Wing Airfoil Eppler E562

“…The higher the angle of attack the wider the vortex formed. Vortex formation begins at the back end of the tip (Genç, Özden, et al 2016) so that if the wingtip is absent it will produce a much larger vortex because the formation of the vortex starts from the front edge / leading edge as shown in Figure 5. Therefore the function of the winglet is to reduce vortex size will be more perfect if the formation of vortex is blocked from the front of the tip.…”

“…will add wake information to Figure 7 which requires a depiction of the y-z axis. This refers to the research of Narayan (Narayan and John 2016), Hariyadi (Setyo Hariyadi, Sutardi, and Widodo 2016), Demir (Demir et al 2016), and Genc (Genç, Özden, et al 2016) (Genç, Özkan, et al 2016).…”

Experimental investigation on effect of partial flexibility at low aspect ratio airfoil – Part I: Installation on suction surface

“…In addition to these control techniques, the bioinspired design such as flexible membrane for MAVs have been started to gain interests and reputations recently. Maximum stall angle and lift coefficient as well as vehicle agility can be ensured with the use of flexible membrane wings for MAVs [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32].…”