소형 무인헬기를 이용한 항공방제기술 (IV) -로터양력의 CFD시뮬레이션 -

Abstract

Aerial application using an unmanned agricultural helicopter became necessary for both labor saving and timely spraying. In the previous paper, a rotor system was developed and lift capability was evaluated. The experimental results were compared with simulated predictions using the CFD-ACE program. From the simulation, the relative velocity on the top surface of the blade airfoil increased, resulting in the pressure drop. The CFD analyses were revealed that a drag resistance on the leading edge of the airfoil, a wake at the trailing edge, and a positive pressure underneath the bottom surface were observed. As the results of the simulation, total lifts of 56.8, 74.4 and <TEX>$95.0kg_f$</TEX> were obtained at the 6, 8 and <TEX>$10^{\circ}$</TEX> of AAT (angle of attack), respectively. The simulation results agreed reasonably up to <TEX>$10^{\circ}$</TEX> of AAT. However, at a greater AAT <TEX>$(<12^{\circ})$</TEX> the simulated total lift continuously increased to <TEX>$105kg_f$</TEX>, comparing with a decreasing experimental total lift due to the lack of engine power. At a stiff angle of <TEX>$18^{\circ}$</TEX> AAT, a wake was observed at the trailing edge of the airfoil. A rated operating condition determined from the previous paper was also verified through the simulation.