Browsing by Author "Huang, Xun"

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    Aerodynamic performance of a flyable flapping wing rotor with dragonfly-like flexible wings
    (Elsevier, 2024-03-29) Pan, Yingjun; Guo, Shijun; Whidborne, James F.; Huang, Xun
    Drawing inspiration from insect flapping wings, a Flapping Wing Rotor (FWR) has been developed for Micro Aerial Vehicle (MAV) applications. The FWR features unique active flapping and passive rotary kinematics of motion to achieve a high lift coefficient and flight efficiency. This study thoroughly investigates the aerodynamic performance and design of a bio-inspired flexible wing for FWR-MAVs, emphasizing its novel backward-curved wingtip and variable spanwise stiffness resembling a dragonfly's wing. The research departs from previous aerodynamic studies of FWR, which focused predominantly on rectangular and rigid wings, and delves into wing flexibility. Employing Computational Fluid Dynamics (CFD), Computational Structural Dynamics (CSD), and experimental measurements, the study demonstrates the aerodynamic benefits of the dragonfly-inspired FWR wingtip shape and its reinforced structure. Fluid-Structure Interaction (FSI) analysis is used to examine the effects of elastic deformation encompassing twist and bending on aerodynamic forces. The results underscore the importance of bending deformation in enhancing lift and power efficiency and propose a method for analysing variable stiffness along the wingspan using a vortex delay mechanism that is induced by delayed flapping motion. By comparing modelled and measured stiffness, the study validates the flexibility of the FWR wing, revealing optimal aerodynamic efficiency is achieved through moderate flexibility and spanwise stiffness variation. The curving leading-edge beam forming the sweep-back wingtip offers a practical approach to obtaining variable stiffness and aerodynamic benefits for FWR-MAVs. Using the same pair of dragonfly-like flexible wings, FWR-MAVs have effectively exhibited VTOL and hovering flight capabilities, spanning from a 25-g single-motor drive model to a 51-g dual-motor drive model. This research provides valuable insights into flexible wing design for FWR-MAVs, leveraging biomimicry to improve flight efficiency.
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    Analysis and testing of a flyable micro flapping-wing rotor with a highly efficient elastic mechanism
    (MDPI, 2024-12-03) Pan, Yingjun; Su, Huijuan; Guo, Shijun; Chen, Si; Huang, Xun
    A Flapping-Wing Rotor (FWR) is a novel bio-inspired micro aerial vehicle configuration, featuring unique wing motions which combine active flapping and passive rotation for high lift production. Power efficiency in flight has recently emerged as a critical factor in FWR development. The current study investigates an elastic flapping mechanism to improve FWRs’ power efficiency by incorporating springs into the system. The elastic force counteracts the system inertia to accelerate or decelerate the wing motion, reducing the power demand and increasing efficiency. A dynamic model was developed to simulate the unique kinematics of the FWR’s wing motions and its elastic mechanism, considering the coupling of aerodynamic and inertial forces generated by the wings, along with the elastic and driven forces from the mechanism. The effects of the spring stiffness on the aerodynamic performance and power efficiency were investigated. The model was then verified through experimental testing. When a spring stiffness close to the mechanical system resonance was applied, the power efficiency of the test model increased by 16% compared to the baseline model without springs, generating an equivalent average lift. With an optimal elastic flapping mechanism for greater lift and lower power consumption, the FWR was fully constructed with onboard power and a control receiver weighing 27.79 g, successfully achieving vertical take-off flight. The current model produces ten times greater lift and has nearly double the wing area of the first 2.6 g flyable FWR prototype.
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    Modelling and simulation of a novel bioinspired flapping-wing rotary MAV
    (German Society for Aeronautics and Astronautics (DGLR: Deutsche Gesellschaft für Luft- und Raumfahrt), 2023-09-07) Huang, Xun; Lu, Linghai; Whidborne, James F.; Guo, Shijun
    Achieving high lift efficiency represents a major research focus in the Micro Air Vehicle (MAV) domain due to stringent size and payload constraints. The Cranfield research team presents a novel semi-biomimetic design called the Flapping Wing Rotor (FWR) to address this challenge. This innovative concept combines a bioinspired flapping wing mechanism with passive rotor rotation, leveraging unsteady aerodynamic principles analogous to insect flight. The research aims to highlight a promising biomimetic flapping-rotor MAV enabled through advanced modeling to unlock the benefits of bio-inspired unsteady aerodynamics. To demonstrate this approach, a 60g proof-of-concept prototype was developed alongside a digital twin methodology for modeling, simulation, and control. A mathematical model has been formulated to analyze FWR's lift generation performance and enable flight control system design for stabilization and controllability. This work concentrates on enhancing the physical modeling process. The model is refined by tuning two key aerodynamic coefficients to account for nonlinearities from unsteady aerodynamics, flexible structures, and low Reynolds number flow inherent in MAV flight. This improved model achieves superior lift prediction accuracy versus real flight test data. Ongoing efforts focus on optimizing control torque, load distribution, and stability to further augment FWR's flight capabilities.
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    Research progress on bio-inspired flapping-wing rotor micro aerial vehicle development
    (Springer, 2024-07-12) Pan, Yingjun; Guo, Shijun; Huang, Xun
    Flapping-wing rotor (FWR) is an innovative bio-inspired micro aerial vehicle capable of vertical take-off and landing. This unique design combines active flapping motion and passive wing rotation around a vertical central shaft to enhance aerodynamic performance. The research on FWR, though relatively new, has contributed to 6% of core journal publications in the micro aerial vehicle field over the past two decades. This paper presents the first comprehensive review of FWR, analysing the current state of the art, key advances, challenges, and future research directions. The review highlights FWR’s distinctive kinematics and aerodynamic superiority compared to traditional flapping wings, fixed wings, and rotary wings, discussing recent breakthroughs in efficient, passive wing pitching and asymmetric stroke amplitude for lift enhancement. Recent experiments and remote-controlled take-off and hovering tests of single and dual-motor FWR models have showcased their effectiveness. The review compares FWR flight performance with well-developed insect-like flapping-wing micro aerial vehicles as the technology readiness level progresses from laboratory to outdoor flight testing, advancing from the initial flight of a 2.6 g prototype to the current free flight of a 60-gram model. The review also presents ongoing research in bionic flexible wing structures, flight stability and control, and transitioning between hovering and cruise flight modes for an FWR, setting the stage for potential applications.