Article
Chemistry, Multidisciplinary
Yuan Yao, Dongli Ma, Liang Zhang, Xiaopeng Yang, Yayun Yu
Summary: This study aims to improve the design optimization of low Reynolds number propellers and the long-endurance capability of ultra-high-altitude unmanned aerial vehicles. By exploring the possibility of extending the Gurney flap on low Reynolds number propellers and using an iterative optimization strategy, significant improvements were achieved. Wind tunnel tests confirmed the effectiveness of the computational fluid dynamics (CFD) method.
APPLIED SCIENCES-BASEL
(2022)
Article
Engineering, Aerospace
Tze How New, Zhen Wei Teo, S. Li, Z. A. Ong, Bjoern Nagel
Summary: The flow behavior and aerodynamic performance of a small-scale joined-wing UAV were investigated under different pitch and yaw angles in subsonic flow conditions. Numerical simulations were compared with experimental results obtained through oil flow visualizations and force measurements. The results revealed the formation of symmetric vortex roll-ups near the fuselage under zero-yaw conditions, but no evidence of such vortices was observed under combined pitch and yaw conditions. Instead, asymmetric flow separations occurred over the fuselage's port side, and they became more complex and interacted with the fuselage and wings as the yaw angle increased. The study also documented the contributions of different pitch and yaw angle combinations to lift and drag coefficients, as well as the flight stability of the UAV.
Article
Engineering, Aerospace
Anmin Zhao, Jun Zhang, Ke Li, Dongsheng Wen
Summary: A novel airborne powered test scheme is proposed in this study to measure the parameters of the electric propulsion system in actual flight. Results show that the innovative test system can measure aircraft propulsion efficiency parameters within 4% accuracy compared to wind tunnel experiments, with potential application for propulsion system optimization and real-time monitoring of power equipment.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Engineering, Marine
Junwei Yang, Hua Yang, Xiangjun Wang, Nailu Li
Summary: The present work aimed to investigate the aerodynamic characteristics of a pitching wind turbine airfoil with a Gurney flap under turbulent inflow. Experimental results showed that with increased turbulence intensity, the differences in lift hysteresis loops between the baseline airfoil and flapped airfoil became smaller. The Gurney flap was found to be more stable in turbulent conditions compared to the baseline airfoil.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2022)
Article
Green & Sustainable Science & Technology
Yosra Chakroun, Galih Bangga
Summary: This study investigates the effects of Gurney flaps on aerodynamic characteristics of an airfoil and a vertical axis wind turbine. The results show that using Gurney flaps increases lift coefficient and power production. Additionally, increasing flap height improves turbine performance.
Article
Chemistry, Multidisciplinary
Liu Chen, Pei Yang, Bingxia Zhang, Lingjie Chen
Summary: This paper investigates the impact of a novel serrated Gurney flap (SGF) on the aerodynamic performance of wind turbines and turbine blades through numerical simulations. The findings show that the SGF reduces the number of trailing edge reverse vortices and decreases drag compared to the plain Gurney flap (PGF). At a certain flap height, the SGF outperforms the PGF in terms of performance.
APPLIED SCIENCES-BASEL
(2023)
Article
Chemistry, Multidisciplinary
Jiawang Mou, Weiping Zhang, Chaofeng Wu, Qingcheng Guo
Summary: This paper addresses the challenges of acquiring an accurate system model and designing a multi-axial adaptive controller for flapping-wing micro aerial vehicles. A control allocation algorithm and lightweight design scheme were proposed, and the effectiveness of the proposed control scheme was verified through simulation and flight tests.
APPLIED SCIENCES-BASEL
(2022)
Article
Engineering, Aerospace
Wenxuan Tang, Peiqing Liu, Tianxiang Hu, Qiulin Qu, Hao Guo, Yuan Liu, Rinie A. D. Akkermans
Summary: The flow control effect of Gurney flaps on 50 degrees swept delta wings during large-amplitude and high-frequency pitching was investigated experimentally and numerically. The results showed that Gurney flaps significantly affected the lift hysteresis and improved lift performance by redistributing vorticity and altering the lower surface pressure.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Engineering, Aerospace
Peter L. Bishay, Christian Aguilar
Summary: Although the benefits of morphing wings have been proven in many studies, the conflicting design requirements of high out-of-plane stiffness and low in-plane stiffness remain a challenge for advancing morphing technology. Advances in hybrid and flexible composites may provide design solutions with a balance in stiffness. A parametric study of a composite skin for twist-morphing wings was conducted, considering design parameters such as the number of plies, fiber-orientation angle, and torsional rigidity. Analysis showed that torsional compliance can be increased by adjusting certain parameters, but at the expense of out-of-plane stiffness. The study highlights the nonlinear relationship and effects of different parameters on the behavior of the skin.
Article
Thermodynamics
D. Lakshmanan, R. Boopathi, P. Saravanan
Summary: This paper investigates the aerodynamic performance and power requirement of wing sections integrated with high-lift airfoil for solar-powered UAVs in low-speed environment. Through wind tunnel testing and computational analysis, the study examines the aerodynamic characteristics and parameters such as lift coefficient, drag coefficient, pressure coefficient, and power needed for steady level flight. The results show that the solar cells positioned at the flow separation region of the UAV wing model achieve an aerodynamic efficiency rate of 5.45% and require a minimum power of 37.13W compared to non-solar UAVs at a Reynolds number of 9.8 x 106.
JOURNAL OF APPLIED FLUID MECHANICS
(2023)
Article
Polymer Science
Huei-Yu Huang, Fang-Yu Fan, Wei-Chun Lin, Chiung-Fang Huang, Yung-Kang Shen, Yi Lin, Muhammad Ruslin
Summary: This study designed and fabricated transmission parts for a flapping-wing micro-aerial vehicle using precision injection molding, and analyzed warpage phenomena. Numerical simulation and experimentation were used to determine causes of warpage and optimize manufacturing parameters for the transmission parts.
Article
Automation & Control Systems
Jun Yang, Cunjia Liu, Matthew Coombes, Yunda Yan, Wen-Hua Chen
Summary: This study introduces a novel path-following algorithm for fixed-wing UAVs, formulating the problem as a control problem by auxiliary dynamics and designing the controller in an optimal and systematic manner. The algorithm compensates for wind disturbances on path-following performance via nonlinear disturbance observers, and its feasibility and effectiveness are validated in simulation studies and flight tests.
IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY
(2021)
Article
Mechanics
Saeed Karimian Aliabadi, Mohamad Reza Parsa, Majid M. Moghadam
Summary: A typical flapping-wing air vehicle is fabricated and tested in a wind tunnel to investigate the impact of kinematic parameters on aerodynamic forces and moments. The hover and landing performance of birds is evaluated considering moderate and high incidence angles. Experimental parameter study reveals that increasing the angle of attack leads to higher lift and reduces axial force during perching. The force hysteresis study indicates that higher flapping frequency and angular velocity can cause dynamic instability.
Article
Acoustics
Ali Esmaeili, Hugo Emanuel da Costa Delgado, Joao Manuel Melo Sousa
Summary: This study explores the possibility of scavenging energy from aeroelastic vibrations to improve the aerodynamic performance of fixed-wing micro aerial vehicles. The passive component of the system generates intense vortices, resulting in vortex-induced vibrations. By installing a piezoelectric energy harvesting device and tuning it for resonant response, the extracted power from structural vibrations can be used to power the active component of the stall control system.
JOURNAL OF VIBRATION AND CONTROL
(2023)
Article
Remote Sensing
Shanique Grant, Jeff Perine, Farah Abi-Akar, Timothy Lane, Brenna Kent, Christopher Mohler, Chris Scott, Amy Ritter
Summary: This study investigated the impact of wind speeds, initial payload volumes, and nozzle droplet size characteristics on drift during spray applications from a hovering UAV. The results showed that increasing wind speed led to a noticeable shift in the sprayed droplets' trajectory. Downwind of the UAV, wind speed had the greatest overall impact on deposition, followed by nozzle/droplet size. Faster wind speeds, finer droplet sizes, and heavier initial payloads were associated with increased drift.
