Wake structure visualization of a flapping-wing Micro-Air-Vehicle in forward flight

Deng, Shuanghou; Oudheusden, B.W. van

doi:10.1016/j.ast.2016.01.003

Cited by 22 publications

(16 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By combining the information obtained in several planes along the span, a reconstruction of the three-dimensional wake flow can be proposed (Spedding et al 2003;Bomphrey et al 2006;Groen et al 2010;Ren et al 2013). A more accurate representation of the 3D flow structure can be obtained from dense multi-plane 2C/3C data, by phase-synchronizing sequentially acquired planes, such as carried out for the flow generated by a flappingwing mechanism (Lu and Shen 2008;Carr et al 2013) and also for reconstruction of the flow in the wake of the DelFly MAV (Percin et al 2014(Percin et al , 2017Deng and van Oudheusden 2016). Evidently, this procedure is laborious and, furthermore, depends critically on cycle repeatability, which does not make it likely a suitable procedure for animal studies, although it was successfully applied for the investigation of butterflies by Fuchiwaki et al (2013).…”

Section: Flow Characterization Of Flapping Flightmentioning

confidence: 99%

“…This approach assumes that the flow structures that are generated by the flapping wings and measured in the wake plane are convected downstream without distortion and at a constant velocity, equal to that of the free stream, thus neglecting the diffusion of the wake structures as well as their deformation as a result of the induced velocities and wing motion. This procedure has been widely applied for the wake investigations of animals Johansson and Hedenström 2009;Hubel et al 2010;Muijres et al 2011) and also for MAVs (Percin et al 2014;Deng and van Oudheusden 2016). This allowed to identify the specific wake structures of different animal species and their dependence on flight regime while further providing a means to quantify how the circulation and spanwise distribution of lift of the wings varies over the flapping cycle.…”

Section: Flow Characterization Of Flapping Flightmentioning

confidence: 99%

“…Measurements carried out at different spanwise positions showed that the LEV had an approximately conical shape up to about 86% of the wingspan, where it was speculated to be connected to the tip vortex. To obtain more detailed three-dimensional information on the flow structure around the wings and in the near wake, phase-synchronized multiplane measurements were performed by (Percin et al 2014(Percin et al , 2017Deng and van Oudheusden 2016). In addition to the true spatial reconstruction of the wake, also the spatio-temporal wake reconstruction using Taylor's hypothesis was investigated, which may be assumed to be reasonable for a (Percin et al 2014;Deng and van Oudheusden 2016).…”

Section: Flow Visualization Research On the Delfly Mavmentioning

confidence: 99%

See 2 more Smart Citations

Large-scale volumetric flow visualization of the unsteady wake of a flapping-wing micro air vehicle

et al. 2019

View full text Add to dashboard Cite

The objective of this experimental investigation is the volumetric visualization of the near wake topology of the vortex structures generated by a flapping-wing micro air vehicle. To achieve the required visualization domain (which in the present experiments amounts to a size of 60,000 cm 3 ), use is made of robotic particle image velocimetry, which implements coaxial illumination and imaging in combination with the use of helium-filled soap bubbles as tracer particles. Particle trajectories are determined via Lagrangian particle tracking and information of different phases throughout the flapping cycle is obtained by means of a phase-averaging procedure applied to the particle tracks. Experiments have been performed at different settings (flow speed, flapping frequency, and body angle) that are representative of actual flight conditions, and the effect of reduced frequency on the wake topology is investigated. Furthermore, experiments have been carried out in both tethered and freeflight conditions, allowing an unprecedented comparison between the aerodynamics of the two conditions. Graphic abstractElectronic supplementary material The online version of this article (https ://doi.org/10.

show abstract

Section: Flow Characterization Of Flapping Flightmentioning

confidence: 99%

Section: Flow Characterization Of Flapping Flightmentioning

confidence: 99%

Section: Flow Visualization Research On the Delfly Mavmentioning

confidence: 99%

See 1 more Smart Citation

Large-scale volumetric flow visualization of the unsteady wake of a flapping-wing micro air vehicle

et al. 2019

View full text Add to dashboard Cite

show abstract

“…For example, at t* = 0.4, which is towards the end of the outstroke, the lower (=right) wing has a much more coherent leading-edge vortex (LEV) than the upper wing. This can be attributed to the smaller effective velocity of the upper (=left) wing due to the forward motion of the DelFly, which also decreases the effective angle of attack and mitigates the flow separation (compare the results of [16]). It may be hypothesized that most of the lift (vertical force, in y direction) is hence generated by the lower wing in this phase, whereas the upper wing mostly accounts for the thrust (horizontal force, in the x direction).…”

Section: Streamwise Planar Flow Visualizationsmentioning

confidence: 99%

“…This will result in upper and lower wings experiencing distinctly different aerodynamic conditions. Tethered flow visualization experiments have been carried out on a different DelFly version at relatively small pitch angles [16], whereas [17] reports on preliminary results of a setup intend to enable free-flight wake visualization by controlling the MAV at a fixed position in the exit of a large wind tunnel. The current investigation takes a different and novel approach by aiming to visualize the unsteady flow structures around the DelFly in actual free forward flight.…”

mentioning

confidence: 99%

Flow Visualization around a Flapping-Wing Micro Air Vehicle in Free Flight Using Large-Scale PIV

et al. 2018

Self Cite

View full text Add to dashboard Cite

Flow visualizations have been performed on a free flying, flapping-wing micro air vehicle (MAV), using a large-scale particle image velocimetry (PIV) approach. The PIV method involves the use of helium-filled soap bubbles (HFSB) as tracer particles. HFSB scatter light with much higher intensity than regular seeding particles, comparable to that reflected off the flexible flapping wings. This enables flow field visualization to be achieved close to the flapping wings, in contrast to previous PIV experiments with regular seeding. Unlike previous tethered wind tunnel measurements, in which the vehicle is fixed relative to the measurement setup, the MAV is now flown through the measurement area. In this way, the experiment captures the flow field of the MAV in free flight, allowing the true nature of the flow representative of actual flight to be appreciated. Measurements were performed for two different orientations of the light sheet with respect to the flight direction. In the first configuration, the light sheet is parallel to the flight direction, and visualizes a streamwise plane that intersects the MAV wings at a specific spanwise position. In the second configuration, the illumination plane is normal to the flight direction, and visualizes the flow as the MAV passes through the light sheet.Aerospace 2018, 5, 99 2 of 15 Quite a variety of visualization PIV studies on animals in free flight have been reported, see e.g., [11][12][13]; however, the direct correspondence to the current MAV configuration is limited. Firstly, most of these studies consider single-wing configurations at relatively fast forward flight, for which the flow dynamics are less complex than for hovering or slow forward flight, especially in the case of counter-flapping wing configurations with large-amplitude and high-frequency stroke behavior, as considered here. Furthermore, flow visualizations reported in literature have predominantly been limited to wake visualizations, while near-wing visualizations suffer in large regions around the wing from reflections or the obstruction of the illumination [13].The MAV used in the current tests is the DelFly II (henceforth called DelFly for simplicity) [3], for which tethered experiments have been previously performed in hovering [14,15] and symmetric forward flight (at zero pitch angle) [9] configurations. These configurations both result in symmetrical flow patterns around the wings, which is not representative of true forward flight, where an appreciable forward velocity is combined with a high pitch angle. This will result in upper and lower wings experiencing distinctly different aerodynamic conditions. Tethered flow visualization experiments have been carried out on a different DelFly version at relatively small pitch angles [16], whereas [17] reports on preliminary results of a setup intend to enable free-flight wake visualization by controlling the MAV at a fixed position in the exit of a large wind tunnel. The current investigation takes a different and novel approach by aiming to visualiz...

show abstract

Numerical investigation of the effects of different parameters on the thrust performance of three dimensional flapping wings

Gong

Han

Yuan

et al. 2019

Aerospace Science and Technology

View full text Add to dashboard Cite

Wake structure visualization of a flapping-wing Micro-Air-Vehicle in forward flight

Cited by 22 publications

References 21 publications

Large-scale volumetric flow visualization of the unsteady wake of a flapping-wing micro air vehicle

Large-scale volumetric flow visualization of the unsteady wake of a flapping-wing micro air vehicle

Flow Visualization around a Flapping-Wing Micro Air Vehicle in Free Flight Using Large-Scale PIV

Numerical investigation of the effects of different parameters on the thrust performance of three dimensional flapping wings

Contact Info

Product

Resources

About