Unsteady flow over flexible wings at different low Reynolds numbers

10th Anniversary International Conference on Experimental Fluid Mechanics -- NOV 17-20, 2015 -- Prague, CZECH REPUBLICWOS: 000400395300032In 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.DANTEC Dynam GmbH, LAVISION, LENAM, MECAS ESI s r o, MIT s r o, TSI GmbHScientific and Technological Research Council of Turkey (TUBITAK) [213M329]; Scientific Research Projects Unit of Erciyes University [FDK-2015-6171, FBG-2014-5337, FDA-2014-5273]The authors would like to acknowledge funding from the Scientific and Technological Research Council of Turkey (TUBITAK) under the project no: 213M329, the Scientific Research Projects Unit of Erciyes University under the contract no: FDK-2015-6171, FBG-2014-5337 and FDA-2014-5273