Nature-inspired in-flight foldable rotorcraft

Bhardwaj, Hitesh; Cai, Xinyu; Win, Luke Soe Thura; Foong, Shaohui

doi:10.1088/1748-3190/acd739

Cited by 3 publications

(1 citation statement)

References 31 publications

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“…A possible application of that is smallradius turning maneuver which is quite essential particularly in the flight of package delivery drones in dense residential districts. In this regard, an in-flight foldable rotorcraft was introduced mimicking what birds usually do in sharp turns and divings [34]. Moreover, avian-inspired simultaneous folding and pitching of the wing in combination with tail folding and deflecting was also conceived in drones for the aforementioned purpose [35].…”

Section: Introductionmentioning

confidence: 99%

Adaptivity of a leaf-inspired wind energy harvester with respect to wind speed and direction

Sabzpoushan,

Woias

2024

Bioinspir. Biomim.

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Environmental wind is a random phenomenon in both speed and direction, though it can be forecasted to some extent. An example of that is a gust which is an abrupt, but short-time change in wind speed and direction. Being a free and clean source for small-scale energy scavenging, attraction of wind is rapidly growing in the world of energy harvesters. In this paper, a leaf-like flapping wind energy harvester is introduced as the base structure in which a short-span airfoil is attached to the free end of a double-deck cantilever beam. A flap mechanism inspired by scales on sharks’ skin and a tail mechanism inspired by birds’ horizontal tail are proposed for integration to the base harvester to make it adaptive with respect to wind speed and direction, respectively. The use of the flap mechanism increases the leaf flapping frequency by +2.1 to +11.5 Hz at wind speeds of 1.5 m/s to 6.0 m/s. Therefore, since the output power of a vibrational harvester is a function of vibration frequency, a figure of merit or an efficiency parameter related to the output power will increase, as well. On the other hand, if there is a misalignment between the harvester’s heading and wind direction due to change of the latter one, the harvesting performance deteriorates. Although the base harvester can realign in certain ranges of sideslip angle at each wind speed, when the tail mechanism is integrated into that, it broadens the range of realignable sideslip angles at all the investigated wind speeds by up to 80°.

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Section: Introductionmentioning

confidence: 99%

Adaptivity of a leaf-inspired wind energy harvester with respect to wind speed and direction

Sabzpoushan,

Woias

2024

Bioinspir. Biomim.

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The novel synthesis of origami-inspired mechanisms based on graph theory

Xia,

Tian,

et al. 2024

Mechanism and Machine Theory

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Effect of a bioinspired upstream extended surface profile on flow characteristics and a drag coefficient of a circular cylinder

Bhuiyan,

Hossain,

Hossain

et al. 2024

MINA

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<abstract> In the current work, the passive drag reduction of a circular cylinder for the subcritical Reynolds number range of 5.67×104 to 1.79×105 was computationally and experimentally investigated. First, inspired by nature, the aerodynamic drag coefficient of a whole Peregrine Falcon was measured in a subsonic wind tunnel for various angles of attack and Reynolds numbers (<italic>Re</italic>) and compared with the bare cylinder. At a 20° angle of attack and <italic>Re</italic> = 5.67×104, the whole falcon model had a 75% lower drag coefficient than the bare cylinder. Later, with the moderate Falcon model, in which the falcon's beak and neck were linked to the cylinder as an extended surface, the drag coefficient decreased up to 72% in the subcritical Reynolds number zone. Finally, the extended surface with a falcon beak profile was connected to the cylinder with a stem and investigated both numerically and experimentally for various stem lengths, angles of attack, and Reynolds numbers. It was found that at low <italic>Re</italic>, the drag coefficient can be reduced by up to 47% for the stem length of 80 mm (<italic>L</italic>/<italic>D</italic> = 1.20) with an angle of attack 10°. The computational investigation yielded precise flow characteristics, and it was discovered that the stem length and the <italic>Re</italic> had a substantial influence on vortex generation and turbulent kinetic energy between the beak and cylinder, as well as downstream of the cylinder. Investigation revealed that percentile drag reduction was much lower for the whole Falcon model over a wide range of Reynolds numbers and positive angles of attack, which exist in nature. Similarly, when compared to the other stem lengths, the 60 mm stem length (<italic>L</italic>/<italic>D</italic> = 0.97) produced similar results to the whole Falcon model. The numerical results were well validated with the experimental results. </abstract>

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Nature-inspired in-flight foldable rotorcraft

Cited by 3 publications

References 31 publications

Adaptivity of a leaf-inspired wind energy harvester with respect to wind speed and direction

Adaptivity of a leaf-inspired wind energy harvester with respect to wind speed and direction

The novel synthesis of origami-inspired mechanisms based on graph theory

Effect of a bioinspired upstream extended surface profile on flow characteristics and a drag coefficient of a circular cylinder

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