Three-dimensional vortex wake structure of a flapping-wing micro aerial vehicle in forward flight configuration

Perçin, Mustafa
Eisma, H. E.
Remes, B. D. W.
This paper investigates the formation and evolution of the unsteady three-dimensional wake structures generated by the flapping wings of the DelFly II micro aerial vehicle in forward flight configuration. Time-resolved stereoscopic particle image velocimetry (Stereo-PIV) measurements were carried out at several spanwise-aligned planes in the wake, so as to allow a reconstruction of the temporal development of the wake of the flapping wings throughout the complete flapping cycle. Simultaneous thrust-force measurements were performed to explore the relation between the wake formation and the aerodynamic force generation mechanisms. The three-dimensional wake configuration was subsequently reconstructed from the planar PIV measurements by two different approaches: (1) a spatiotemporal wake reconstruction obtained by convecting the time-resolved, three-component velocity field data of a single measurement plane with the free-stream velocity; (2) for selected phases in the flapping cycle a direct three-dimensional spatial wake reconstruction is interpolated from the data of the different measurement planes, using a Kriging regression technique. Comparing the results derived from both methods in terms of the behavior of the wake formations, their phase and orientation indicate that the spatiotemporal reconstruction method allows to characterize the general three-dimensional structure of the wake, but that the spatial reconstruction method can reveal more details due to higher streamwise resolution. Comparison of the wake reconstructions for different values of the reduced frequency allows assessing the impact of the flapping frequency on the formation and interaction characteristics of the vortical structures. For low values of the reduced frequency, it is observed that the vortex structure formation of instroke and outstroke is relatively independent of each other, but that increasing interaction occurs at higher reduced frequencies. It is further shown that there is a phase lag in the appearance of the structures for increasing flapping frequency, which is in correlation with the generation of the forces. Comparison of thrust generated during the instroke and the outstroke phases of the flapping motion in conjunction with the development of the wake structures indicates that wing-wing interaction at the start of outstroke (peel motion) becomes a dominant feature for reduced frequencies greater than 0.62.


Flow Structures Around a Flapping-Wing Micro Air Vehicle Performing a Clap-and-Peel Motion
Perçin, Mustafa; Remes, Bart (2017-04-01)
The vortical flow structures generated by the flapping wings of the DelFly II micro air vehicle in hovering flight configuration are investigated using particle image velocimetry. Synchronous force measurements are carried out to establish the relation between the unsteady forces and force generation mechanisms: particularly, the leading-edge vortex and the clap-and-peel motion. The formation of conical leading-edge vortices on both wings is revealed, which occurs rapidly at the start of the outstroke as a ...
Three dimensional aerodynamic analysis of missiles by a panel method
Başoğlu, Osman; Özyörük, Yusuf; Department of Aeronautical Engineering (2002)
Panel methods are extensively used in aerodynamic analysis of missiles in early stages of their development. An existing TUBİTAK-SAGE panel code is modified and improved for routine and more efficient calculation of the aerodynamic coefficients of various missile configurations at subsonic and supersonic flight conditions. Particularly, the poor convergence, user unfriendliness and poor output characters of this code have been improved by modifying and adding new routines to it. Now the code with an incorpo...
Vortex Formation and Force Generation Mechanisms of the DelFly II in Hovering Flight
Tenaglia, A; Perçin, Mustafa; Van Oudheusden, Bas W.; Deng, Shuanghou; Remes, Bart (2014-08-12)
This paper addresses the unsteady aerodynamic mechanisms in the hovering flight of the DelFly II flapping-wing Micro Aerial Vehicle (MAV). Stereoscopic Particle Image Velocimetry (Stereo-PIV) were carried out around the wings at a high framing rate. Thrust-force was measured to investigate the relation between the vortex dynamics and the aerodynamic force generation. The results reveal that the Leading-Edge-Vortex (LEV), as well as the high flexibility of the wings, have a major effect on thrust generation....
Flow Visualization in the Wake of the Flapping-Wing MAV ’DelFly II’ in Forward Flight
Perçin, Mustafa; van Oudheusden, Bas W.; Remes, Bart; Ruijsink, R; de Wagter, C (2012-06-25)
Time-resolved velocity field measurements in the wake of the flapping wings of the DelFly II Micro Aerial Vehicle (MAV) in forward flight configuration were obtained by Stereoscopic Particle Image Velocimetry (Stereo-PIV). The PIV measurements were performed at several spanwise planes in the wake of the flapping wings and at a high framing rate to allow a reconstruction of the temporal development of the three dimensional wake structures throughout the flapping cycle. The wake reconstruction was performed b...
Investigation of rotor rotor interactions for two helicopters in forward flight using free vortex wake methodology
Tonkal, Ozan Çağrı; Pehlivan, Sercan; Sezer Uzol, Nilay; İşler, Veysi (null; 2010-07-01)
This paper presents an investigation of the aerodynamic interactions between two UH-1H helicopter rotors in forward flight. The wake flow structure and performance characteristics of the rotors are investigated when the rear rotor is operating within the wake of the front rotor. A 3-D unsteady vortex-panel method potential flow solver based on a free-vortex-wake methodology is used for this purpose. The solver is validated using the experimental data from the Caradonna-Tung experiments. The interactional an...
Citation Formats
M. Perçin, H. E. Eisma, and B. D. W. Remes, “Three-dimensional vortex wake structure of a flapping-wing micro aerial vehicle in forward flight configuration,” EXPERIMENTS IN FLUIDS, pp. 0–0, 2014, Accessed: 00, 2020. [Online]. Available: