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http://dx.doi.org/10.5139/JKSAS.2018.46.5.359

Measurement of the Flow Field Around a Quadcopter in Vertical Descending Flight  

Kwon, Min-Jeong (Department of Aerospace System Engineering, Korea University of Science & Technology)
Kwon, Ki-Jung (Aerodynamic Research Team, KARI(Korea Aerospace Research Institute)
Publication Information
Journal of the Korean Society for Aeronautical & Space Sciences / v.46, no.5, 2018 , pp. 359-367 More about this Journal
Abstract
The vortex ring state that occurs during the descending flight of a rotorcraft generates a circulating flow like a donut near the rotating surface, and it often causes a rotorcraft fall due to loss of thrust. In this paper, we have physically identified the flow field in the vortex ring state of the quadcopter, one of the types of unmanned aerial vehicles. The descending flight of the quadcopter was simulated in a 1m subsonic wind tunnel of the Korea Aerospace Research Institute(KARI) and the Particle Image Velocimetry(PIV) was used for the flow field measurement. The induced velocity in the hovering state is estimated by using the momentum theory and the test was carried out in the range of descent rate at which the vortex ring condition could be caused. The development and the direction of the vortex ring were confirmed by the measurement of the flow field according to not only the descent rate but also propeller separation distance. In addition, the results of the study show the vortex ring state can be predicted sufficiently by measuring the flow velocity around the quadcopter.
Keywords
Quadcopter; Vortex Ring State; Descent Rate; Propeller Separation Distance; Particle Image Velocimetry; Wind Tunnel Test;
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