Force moment partitioning and scaling analysis of vortices shed by a 2D pitching wing in quiescent fluid

Zhu, Yuanhang; Lee, Howon; Kumar, Sushrut; Menon, Karthik; Mittal, Rajat; Breuer, Kenneth

doi:10.1007/s00348-023-03698-5

Cited by 2 publications

(4 citation statements)

References 55 publications

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“…The slight asymmetry of with respect to the pitching axis (see figure 9 d ) is caused by the difference between the rounded leading edge and the sharp trailing edge of the NACA 0012 wing (see also the two-dimensional influence field reported in Zhu et al. 2023). The size of the iso- surfaces stays relatively constant along the wing span, except at the wing tip, where the surfaces wrap around and seal the tube.…”

Section: Resultsmentioning

confidence: 75%

“…The contributions from these other forces, along with experimental errors, might result in a mismatch in the magnitude of the FMPM-estimated force and force transducer measurements, as shown by Zhu et al. (2023), and the exact source of this mismatch is under investigation.…”

Section: Methodsmentioning

confidence: 98%

“…Zhu et al. (2023) employed the FMPM to analyse the vortex dynamics of a two-dimensional wing pitching sinusoidally in a quiescent flow. Several practical issues in applying the FMPM to PIV data were discussed, including the effect of phase-averaging and potential error sources.…”

Section: Introductionmentioning

confidence: 99%

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Flow-induced oscillations of pitching swept wings: stability boundary, vortex dynamics and force partitioning

Zhu,

Breuer

2023

J. Fluid Mech.

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We study experimentally the aeroelastic instability boundaries and three-dimensional vortex dynamics of pitching swept wings, with the sweep angle ranging from 0 $^\circ$ to 25 $^\circ$ . The structural dynamics of the wings are simulated using a cyber-physical control system. With a constant flow speed, a prescribed high inertia and a small structural damping, we show that the system undergoes a subcritical Hopf bifurcation to large-amplitude limit-cycle oscillations (LCOs) for all the sweep angles. The onset of LCOs depends largely on the static characteristics of the wing. The saddle-node point is found to change non-monotonically with the sweep angle, which we attribute to the non-monotonic power transfer between the ambient fluid and the elastic mount. An optimal sweep angle is observed to enhance the power extraction performance and thus promote LCOs and destabilize the aeroelastic system. The frequency response of the system reveals a structural-hydrodynamic oscillation mode for wings with relatively high sweep angles. Force, moment and three-dimensional flow structures measured using multi-layer stereoscopic particle image velocimetry are analysed to explain the differences in power extraction for different swept wings. Finally, we employ a physics-based force and moment partitioning method to correlate quantitatively the three-dimensional vortex dynamics with the resultant unsteady aerodynamic moment.

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Section: Resultsmentioning

confidence: 75%

Section: Methodsmentioning

confidence: 98%

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Flow-induced oscillations of pitching swept wings: stability boundary, vortex dynamics and force partitioning

Zhu,

Breuer

2023

J. Fluid Mech.

Self Cite

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“…Though the lift estimation was in agreement, the drag had an error of 17%, which is one order higher than that of the lift. Zhu et al (2023) applied FMPM to PIV velocity data to estimate the aerodynamic moment acting on a sinusoidally pitching NACA 0012 aerofoil in quiescent water. The estimated moment saw a qualitative match with that of the direct force measurement, but the disagreement was large as the estimated moment was approximately 50% smaller.…”

Section: Introductionmentioning

confidence: 99%

Vortex force map method to estimate unsteady forces from snapshot flowfield measurements

Otomo,

Gehlert,

Babinsky

et al. 2024

Preprint

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An accurate non-intrusive force measurement is challenging in many situations especially those involving animals and vehicles. This paper reports a non-intrusive technique based on the vortex force map (VFM) method, which computes forces from snapshot velocity and vorticity fields obtained from the particle image velocimetry (PIV) flow measurement. This study is the first application of the VFM method to PIV velocity data. The VFM method is applied to three different kinematic families for surging flat plates and pitching NACA~0018 aerofoils at Reynolds numbers of O(104), where flowfields are characterised by a massive flow separation with the shedding of the coherent leading-edge vortex and trailing-edge vortex. In all three cases, we observe a remarkable agreement between the direct force measurements and the VFM method even if a relatively small region around aerofoils is captured for PIV. Moreover, physical explanations of the linkage between the forces and vortical structures are provided based on the visualised force contribution of each vortex. The VFM method is highly robust to noise (a significant feature in experimental fluid mechanics) and can be applied to snapshot data.

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Force moment partitioning and scaling analysis of vortices shed by a 2D pitching wing in quiescent fluid

Cited by 2 publications

References 55 publications

Flow-induced oscillations of pitching swept wings: stability boundary, vortex dynamics and force partitioning

Flow-induced oscillations of pitching swept wings: stability boundary, vortex dynamics and force partitioning

Vortex force map method to estimate unsteady forces from snapshot flowfield measurements

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