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Autonomous Vehicles for Infrastructure Inspection Applications
Published in Diego Galar, Uday Kumar, Dammika Seneviratne, Robots, Drones, UAVs and UGVs for Operation and Maintenance, 2020
Diego Galar, Uday Kumar, Dammika Seneviratne
The coaxial rotor configuration is more expensive to build and maintain, but it requires less space, while producing the same amount of lift as the other two configurations. This results in a smaller and more maneuverable helicopter for the same payload limitations. The coaxial configuration has better maneuverability than the Sikorsky configuration but is more expensive and has more frequent maintenance. For the climbing-flying robot, the coaxial configuration is, therefore, the best choice (Katrasnik, Pernus, & Likar, 2008a).
Numerical investigation of rotor loads of a shipborne coaxial-rotor helicopter during a vertical landing based on moving overset mesh method
Published in Engineering Applications of Computational Fluid Mechanics, 2019
Dacheng Su, Guohua Xu, Shuilin Huang, Yongjie Shi
This is the motivation behind conducting the present research. A ship/coaxial-rotor configuration is used in the paper to characterize the rotor loads of a shipborne coaxial-rotor helicopter during the vertical landing. In order to achieve two-way coupling and overcome the limitations of the momentum source method in simulating unsteady aerodynamic interactions, the moving overset mesh method (Meakin, 1991) is employed to investigate the effects of the highly unsteady phenomena (i.e. ground effect and recirculation flow regime) on the coaxial-rotor helicopter through this phase. First, coupled simulations are conducted for various rotor heights along a vertical descent path. Results in terms of time-averaged and Root-Mean-Square (RMS) loads are analyzed to identify the pilot workload and control strategy as the coaxial-rotor helicopter moves to the landing spot. Also, the influences of ground effect and recirculation flow regime are studied in this process. The distributions of turbulence intensity and the velocity over the flight deck are analyzed to explore the reasons behind the results. Then, the effects of hangar-door state and the landing spot location on the rotor loads of the coaxial rotor are discussed in detail. By the present investigation, it is shown that the ground effect and recirculation flow regime have significant influence on control margins and unsteady loading levels. Opening the hangar-door or descending a helicopter to a landing spot which is more closed to the hangar can decrease the RMS levels considerably, especially during the latter stage of vertical descent.
Proactive maintenance of small wind turbines using IoT and machine learning models
Published in International Journal of Green Energy, 2022
Yoganand Selvaraj, Chithra Selvaraj
D. Kapoor et al. [2012, 19] proposes an adaptive controller to provide for failure compensation for a coaxial rotor helicopter. It addresses the problem of instability due to damage to the rotors in a coaxial rotor helicopter, where degradation of or unexpected variations in thrust from the propellers are known to pose an especially serious risk.