Versatile reduced-order model of leading-edge vortices on rotary wings

Chen, D.; Kolomenskiy, Dmitry; Onishi, Ryo; Liu, H.

doi:10.1103/physrevfluids.3.114703

Cited by 7 publications

(4 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The majority of large insects have solid wings that consist of thin, impermeable membranes reinforced with veins [13]. The significance of three-dimensional wing shape and outline on lift-generating leading edge vortices (LEVs) has been extensively addressed in the literature [14][15][16][17][18]. In contrast with solid wings, bristled wings feature complex fluid flows that combine flows around each bristle at Re below unity with flows around the entire wing at low-to-medium Re [10,19].…”

Section: Introductionmentioning

confidence: 99%

Flight efficiency is a key to diverse wing morphologies in small insects

Engels

Kolomenskiy

Lehmann

2021

J. R. Soc. Interface.

View full text Add to dashboard Cite

Insect wings are hybrid structures that are typically composed of veins and solid membranes. In some of the smallest flying insects, however, the wing membrane is replaced by hair-like bristles attached to a solid root. Bristles and membranous wing surfaces coexist in small but not in large insect species. There is no satisfying explanation for this finding as aerodynamic force production is always smaller in bristled than solid wings. This computational study suggests that the diversity of wing structure in small insects results from aerodynamic efficiency rather than from the requirements to produce elevated forces for flight. The tested wings vary from fully membranous to sparsely bristled and were flapped around a wing root with lift- and drag-based wing kinematic patterns and at different Reynolds numbers ( Re ). The results show that the decrease in aerodynamic efficiency with decreasing surface solidity is significantly smaller at Re = 4 than Re = 57. A replacement of wing membrane by bristles thus causes less change in energetic costs for flight in small compared to large insects. As a consequence, small insects may fly with bristled and solid wing surfaces at similar efficacy, while larger insects must use membranous wings for an efficient production of flight forces. The above findings are significant for the biological fitness and dispersal of insects that fly at elevated energy expenditures.

show abstract

Section: Introductionmentioning

confidence: 99%

Flight efficiency is a key to diverse wing morphologies in small insects

Engels

Kolomenskiy

Lehmann

2021

J. R. Soc. Interface.

View full text Add to dashboard Cite

show abstract

“…The effect was prominent in all β cases at J = 0.58, but at J = 1.0, it was drastically reduced at β > 0 deg. Considering that the wing in this case had a much stronger spanwise flow than those of J = 0.58 due to the higher U ∞ , it can be seen that the excessive spanwise flow, which overly convected the vorticity of an inboard LEV to the wingtip, reduced the coverage of the LEV and the benefit in the lift production, even it can more stabilize the overall LEV system (refer to [25,26] for the structure diagnosis on the LEV). Relatively lower α at J = 1.0, which provided less pressure difference on the upper surface, must have stimulated the convection along a wingspan.…”

Section: Resultsmentioning

confidence: 99%

Aerodynamic investigation on shifted-back vertical stroke plane of flapping wing in forward flight

Han

Breitsamter

2021

Bioinspir. Biomim.

View full text Add to dashboard Cite

In order to properly understand aerodynamic characteristics in a flapping wing in forward flight, additional aerodynamic parameters apart from those in hover—an inclined stroke plane, a shifted-back stroke plane, and an advance ratio—must be comprehended in advance. This paper deals with the aerodynamic characteristics of a flapping wing in a shifted-back vertical stroke plane in freestream. A scaled-up robotic arm in a water towing tank was used to collect time-varying forces of a model flapping wing, and a semi-empirical quasi-steady aerodynamic model, which can decompose the forces into steady, quasi-steady, and unsteady components, was used to estimate the forces of the model flapping wing. It was found that the shifted-back stroke plane left a part of freestream as a non-perpendicular component, giving rise to a time-course change in the aerodynamic forces during the stroke. This also brought out two quasi-steady components (rotational and added-mass forces) apart from the steady one, even the wing moved with a constant stroke velocity. The aerodynamic model underestimated the actual forces of the model flapping wing even it can cover the increasingly distributed angle of attack of the vertical stroke plane with a blade element theory. The locations of the centers of pressure suggested a greater pressure gradient and an elongated leading-edge vortex along a wingspan than that of the estimation, which may explain the higher actual force in forward flight.

show abstract

“…Moreover, Chen et al. (2018) developed a closed-form analytical expression for the LEV position and circulation for rotating wings with various shapes, by setting a free parameter for the spanwise vorticity transport.…”

Section: Introductionmentioning

confidence: 99%

“…Limacher, Morton & Wood (2016) simplified the Navier-Stokes equations to predict the LEV-core streamline, which agreed well with experiments inboard of the tip. Moreover, Chen et al (2018) developed a closed-form analytical expression for the LEV position and circulation for rotating wings with various shapes, by setting a free parameter for the spanwise vorticity transport. Some of the models described above are too computationally expensive to be readily used for engineering design or control, and low-order models are meant to address this.…”

mentioning

confidence: 99%

A simple vortex-loop-based model for unsteady rotating wings

Chowdhury

Ringuette

2019

J. Fluid Mech.

View full text Add to dashboard Cite

An analytical model is developed for the lift force produced by unsteady rotating wings; this configuration is a simple representation of a flapping wing. Modelling this is important for the aerodynamic and control-system design for bio-inspired drones. Such efforts have often been limited to being two-dimensional, semi-empirical, sometimes computationally expensive, or quasi-steady. The current model is unsteady and three-dimensional, yet simple to implement, requiring knowledge of only the wing kinematics and geometry. Rotating wings produce a vortex loop consisting of the root vortex, leading-edge vortex, tip vortex and trailing-edge vortex, which grows with time. This is modelled as a tilted planar loop, geometrically specified by the wing size, orientation and motion. By equating the angular impulse of the vortex loop to that of the fluid volume driven by the wing, the circulatory lift force is derived. Potential flow theory gives the fluid-inertial lift. Adding these two contributions yields the total lift formula. The model shows good agreement with a range of experimental and computational cases. Also, a steady-state lift model is developed that compares well with previous work for various angles of attack.

show abstract

Versatile reduced-order model of leading-edge vortices on rotary wings

Cited by 7 publications

References 21 publications

Flight efficiency is a key to diverse wing morphologies in small insects

Flight efficiency is a key to diverse wing morphologies in small insects

Aerodynamic investigation on shifted-back vertical stroke plane of flapping wing in forward flight

A simple vortex-loop-based model for unsteady rotating wings

Contact Info

Product

Resources

About