Free-stream turbulence interaction with a wing-tip vortex

Miloud, Kamal Ben; Dghim, Marouen; Fellouah, Hachimi; Ferchichi, Mohsen

doi:10.1016/j.jweia.2020.104211

Cited by 7 publications

(2 citation statements)

References 39 publications

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“…The streamwise evolution of the wandering amplitude σ r agrees well with that of the spatial-averaged turbulence intensity I within the entire measured area, indicating that the wandering motion is highly correlated with the local turbulence. This phenomenon is consistent with previous observations that the wandering motion is sensitive to the external turbulence and the wandering amplitude increases with increasing local turbulence intensity (Heyes et al, 2004;Bailey and Tavoularis, 2008;Miloud et al, 2020). Another phenomenon is that the incident angle of hydrofoil and the Reynolds number have a weaker effect on the wandering motion in the near field.…”

Section: The Near-field Wandering Motionsupporting

confidence: 91%

An experimental study on near-field tip vortex of an elliptical hydrofoil using tomographic particle image velocimetry

Zhao

She

et al. 2023

Preprint

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Volumetric measurement for the non-cavitating tip vortex in the near field of an elliptical hydrofoil is conducted using tomographic particle image velocimetry (TPIV), which provides a fully three-dimensional diagnose of the vortex formation and development. The wandering motion and flow properties of the near-field tip vortex under different incident angles and Reynolds numbers are investigated in detail. Unlike in the far field, the wandering motion in the near field is mainly subject to the local flow unsteadiness rather than the flow condition. By the "re-centered" post-processing, the deviations introduced by the wandering motion can be technically corrected, and more accurate vortex properties can be thus obtained. In the near field, a turning point of the vortex center trajectory is detected, the position of which is basically independent of the flow condition. By investigating the local flow properties, it is found that this turning point is the position where the tip vortex completely leaves the trailing edge of hydrofoil and enters the wake region. At this turning point, the external supply to the vortex core starts to be restricted, and the vortex circulation reaches a rather constant value. Further according to the local flow properties, the development process of the near-field tip vortex can be divided into three stages: vortex-attached stage, vortex-lifting stage and vortex-detached stage, which are found to be closely relevant to the hydrofoil configuration.

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Section: The Near-field Wandering Motionsupporting

confidence: 91%

An experimental study on near-field tip vortex of an elliptical hydrofoil using tomographic particle image velocimetry

Zhao

She

et al. 2023

Preprint

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show abstract

“…8,21,26 Because the flow is assumed to be irrotational, this method would be inappropriate for use in an unsteady, turbulent scenario, as an increase in freestream turbulence would result in the decay of wingtip vortices. 31 Furthermore, the UVLM would not accurately capture the additional unsteady loading on the wing caused by the turbulence. 32 The method is based on dividing the wing surface into rectangular vortex elements; each element consists of four vortex segments of the same circulation.…”

Section: Theoretical Background and Computational Implementationmentioning

confidence: 99%

Unsteady aerodynamic analysis and effectiveness of bio-inspired flapping wings in V-formation flight

Billingsley

Ghommem

Vasconcellos

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part G:

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Several bird species have been observed to fly in V-formation, an arrangement which exploits aerodynamic features to allow the group to conserve energy when migrating over long distances without stopping and feeding. The use of such grouping arrangement and organized pattern has demonstrated longer endurance and less power consumption in comparison with single flights. In this work, a computationally efficient potential flow solver based on the unsteady vortex lattice method (UVLM) is employed to assess the aerodynamic performance of flapping wings in forward flight in terms of lift and thrust generation along with the propulsive efficiency. The UVLM has the capability to simulate incompressible and inviscid flows over moving thin wings where the separation lines are known a priori. A bio-inspired, albatross wing shape is considered and its aerodynamic performance in formation flights is compared against conventional elliptical and rectangular wing shapes. The aerodynamic analysis is carried out for different wing arrangements of 3-body and 5-body V-formations to determine the optimal spacing parameters leading to maximum propulsive efficiency. The simulation results reveal that, at the optimal formation angle and separation distance, the albatross-inspired wing shape produces the most lift over the flapping cycle, while the rectangular wing shape generates the most thrust over the flapping cycle. Furthermore, the optimal configuration in terms of propulsive efficiency is found to be a 5-body V-formation utilizing the albatross wing shape with a separation distance set to one-third of the span and a formation angle set to 139°. The present study provides guidance for the design of multi-flapping wing air vehicles based on the expected flight mission. The albatross wing shape is found to have superior capability in producing lift, while the elliptical wing shape is observed to consume less power. The rectangular wing shape is found to produce higher thrust and then can achieve faster forward motion.

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An experimental study on near-field tip vortex of an elliptical hydrofoil using tomographic particle image velocimetry

Zhao,

Tu,

She

et al. 2023

Exp Fluids

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Free-stream turbulence interaction with a wing-tip vortex

Cited by 7 publications

References 39 publications

An experimental study on near-field tip vortex of an elliptical hydrofoil using tomographic particle image velocimetry

An experimental study on near-field tip vortex of an elliptical hydrofoil using tomographic particle image velocimetry

Unsteady aerodynamic analysis and effectiveness of bio-inspired flapping wings in V-formation flight

An experimental study on near-field tip vortex of an elliptical hydrofoil using tomographic particle image velocimetry

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