INVESTIGATION OF PROPELLER DESIGN EFFECT ON LIFT AND DRAG PERFORMANCE OF SMALL UAV

The past few years witnessed an elevated interest in developing and using the unmanned aerial vehicles (UAVs) as a means of gathering information both for military and scientific missions. The time lengths of their flights are... [ view full abstract ]

The past few years witnessed an elevated interest in developing and using the unmanned aerial vehicles (UAVs) as a means of gathering information both for military and scientific missions. The time lengths of their flights are limited by fuel consumption and consequently depend on the vehicle lift and drag performance. Improving such performance is dramatically effected by selecting the proper propeller design since the motion of these aerial vehicles is controlled by the speed of their downward thrusting motor/ propeller units. A propeller is actually a rotating wing of 2 or more blades with airfoil cross-sections. The propeller converts the torque of its power source into thrust and the rotational speed into linear speed, thus the flight path of any blade section is helical. The aerodynamic forces of this complex trailing vortex system are resultants of the perpendicular forces (lift) and parallel forces (drag) acting on the flight paths.
The performance of the propeller was assessed by computing its efficiency, η as well as the thrust and power coefficients, CT and CP in both static and dynamic states for a 9x4.7 Slow Flyer propeller. The performance was studied both numerically and by using CFD model. It was meant to assess the accuracy of the analytical and computational modelling versus expensive and time-consuming wind tunnel tests. While investigating the performance of the propeller is crucial, but the importance of the propeller data can be directly co-related to airfoil data, hence analyzing the airfoil’s boundary layer flow was performed. A MATLAB code was developed for predicting the velocity ranges based on Panel method, which can be a good alternative to CFD modelling for more complex geometries where capturing the fine velocity fluctuations may be questioned.