Vortex topology of a pitching and rolling wing in forward flight

Johnson, Kyle; Thurow, Brian S.; Wabick, Kevin; Berdon, Randall; Buchholz, James

doi:10.1007/s00348-020-03048-9

Cited by 4 publications

(4 citation statements)

References 59 publications

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“…Four different combinations of kinematics and geometry were investigated by choosing two different values of advance coefficient, and 1.36, and two dimensionless radii of gyration, and 2.5 – a subset of the parameter values investigated by Johnson et al. (2020). Here, is the radius of gyration of the wing, and is the roll rate.…”

Section: Methodsmentioning

confidence: 99%

“…Specific application of the method to the present data is detailed in Johnson et al. (2020), and summarized below.…”

Section: Methodsmentioning

confidence: 99%

“…In a prior publication by the present authors (Johnson et al. 2020), plenoptic PIV was employed to characterize LEV behaviour on a wing revolving in the presence of a free stream. For sufficiently small advance ratios (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…In the present work, we further examine the formation of LEVs on a wing revolving in a free stream using the same configuration investigated by Johnson et al. (2020). A detailed vorticity transport framework is used, which is formulated as a budget within a planar control region in a non-inertial reference frame attached to the wing.…”

Section: Introductionmentioning

confidence: 99%

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Transient leading-edge vortex development on a wing rolling in uniform flow

Wabick

Johnson²,

Berdon³

et al. 2023

J. Fluid Mech.

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Plenoptic particle image velocimetry and surface pressure measurements were used to analyse the early development of leading-edge vortices (LEVs) created by a flat-plate wing of aspect ratio 2 rolling in a uniform flow parallel to the roll axis. Four cases were constructed by considering two advance coefficients, $J=0.54$ and 1.36, and two wing radii of gyration, $R_g/c=2.5$ and 3.25. In each case, the wing pitch angle was articulated such as to achieve an angle of attack of $33^{\circ }$ at the radius of gyration of the wing. The sources and sinks of vorticity were quantified for a chordwise rectangular control region, using a vorticity transport framework in a non-inertial coordinate system attached to the wing. Within this framework, terms associated with Coriolis acceleration provide a correction to tilting and spanwise convective fluxes measured in the rotating frame and, for the present case, have insignificant values. For the baseline case ( $J=0.54, R_g/c=3.25$ ), three distinct spanwise regions were observed within the LEV, with distinct patterns of vortex evolution and vorticity transport mechanisms in each region. Reducing the radius of gyration to $R_g/c=2.5$ resulted in a more stable vortex with the inboard region extending over a broader spanwise range. Increasing advance ratio eliminated the conical vortex, resulting in transport processes resembling the mid-span region of the baseline case. Although the circulation of the LEV system was generally stronger at the larger advance coefficient, the shear-layer contribution was diminished.

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Section: Methodsmentioning

confidence: 99%

“…Specific application of the method to the present data is detailed in Johnson et al. (2020), and summarized below.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Transient leading-edge vortex development on a wing rolling in uniform flow

Wabick

Johnson²,

Berdon³

et al. 2023

J. Fluid Mech.

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Natural Vibration Characteristics of a Cantilever Beam Parametrically Excited by Pitch Motion

Li,

Zhu,

Wang

et al. 2024

Int. J. Str. Stab. Dyn.

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Natural vibration characteristics of a cantilever beam that is parametrically excited by pitch motion are theoretically investigated in this work. A partial differential equation governing the parametrically excited bending vibration of the beam is established by employing the generalized Hamiltonian principle. Normal modal functions of the bending vibration are obtained based on the method of separation of variables. It reveals that the dynamic pitch motion cannot change the modal shapes of the bending vibration of a uniform beam. Principal vibrations of the beam are studied by taking into account two cases of [Formula: see text] and [Formula: see text], where [Formula: see text] and [Formula: see text] are the first and second principal bending stiffness, respectively. The bending stiffness is considered as the superposition of a constant stiffness with a small perturbation. With the aid of the Fourier series theory and the method of multiple scales, the principal vibrations of the parametrically excited system at non-resonant and resonant cases are analyzed by introducing a small natural parameter [Formula: see text], while natural vibration characteristics of the beam are obtained and the orthogonal properties of modal functions are illustrated. Theoretical methods provided in this work are verified by using the finite element method, assumed modes method and direct numerical integrations to the governing equation based on a rectangular beam model. It reveals that theoretical results coincide with numerical results very well. Finally, the influences of design parameters including the beam height, beam width, beam length, slender ratio, aspect ratio, pitch amplitude, pitch frequency and pitch phase on natural frequencies of a harmonic pitching beam are discussed. It shows that the width, height, length, slender ratio, aspect ratio and pitch amplitude have dramatic influences on the natural frequencies of the pitching beam, while the pitch frequency and pitch phase have little effect on natural frequencies.

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Development of raw-image ray-bundling for focused and unfocused plenoptic 3D-PTV

Chen,

Tan

2024

Opt. Express

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This paper introduces a new plenoptic 3D particle tracking velocimetry (3D-PTV) technique called raw-image ray-bundling (RIRB), which combines the 3D clustering algorithm of light-field ray-bundling (LFRB) with the raw image segmentation concept of epipolar triangular connectivity (ETC). The combined approach provides flexibility towards accommodating both unfocused and focused plenoptic cameras. Additionally, the RIRB algorithm bypasses the computational step of perspective-view generation in LFRB, thereby allowing lower specification microlens arrays (MLA) to be used without excessive loss of measurement resolution. As part of RIRB’s development, synthetic particle-field data and experimental dot-panel targets were used to demonstrate the viability of RIRB. The latter was performed through a VEO640 high-speed camera retrofitted for plenoptic imaging with a 2.5 mm focal-length, F/10 MLA. For the synthetic dataset, RIRB demonstrated better performance than LFRB in processing low-resolution images, with mean errors below 0.85% of the field-of-view (FOV). Additionally, a synthetic Hagen-Poiseuille flow dataset was used to demonstrate the feasibility of RIRB for 3D flow velocimetry using both high and low-resolution images. For the experimental dataset, x/y errors below 0.15% of the FOV and z error below 1.0% were achieved. The combination of synthetic and experimental validations suggests RIRB is a promising approach for 3D triangulation from both focused and unfocused raw plenoptic images, overcoming the low-resolution issue inherent with perspective-view decoding in plenoptic systems.

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Vortex topology of a pitching and rolling wing in forward flight

Cited by 4 publications

References 59 publications

Transient leading-edge vortex development on a wing rolling in uniform flow

Transient leading-edge vortex development on a wing rolling in uniform flow

Natural Vibration Characteristics of a Cantilever Beam Parametrically Excited by Pitch Motion

Development of raw-image ray-bundling for focused and unfocused plenoptic 3D-PTV

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