생체 모방을 이용한 프로펠러의 공력 특성에 관한 수치적 연구

Abstract

It was applied to the leading edge tubercles of the small UAV propeller to improve the aerodynamic characteristics of forward flight condition. As the angle of attack changes from 0° to 90°, the forward flight speed is varied from 4 m/s to 16 m/s. The rotating speed of propeller is from 3,500 RPM to 5,100 RPM in this study. A change in the flow was observed around the propellers with tubercles at the leading edge of the blades. At lower advance ratio, the power and thrust coefficients of all models are similar to each other within the uncertainty range. However, as the advance ratio increased, the increase in efficiency of the propellers with leading edge tubercles improved in comparison with the base model. It was noted that the addition of the leading edge tubercles to the UAV propeller delayed flow separation, reduced spanwise flow and the size and strength of the blade tip vortices. The advance ratio and angle of attack effects are expected to be the main contributing factors to the propeller aerodynamics. In oblique flow, the freestream velocity can be decomposed into the axial and the in-plane component of the propeller and the propeller will produce forces and moments other than the axial thrust and torque. It is considered necessary to study the in-plane component additionally.