Optimization Design of Propeller for Ultra-high-altitude Unmanned Aerial Vehicle

Ultra-high-altitude unmanned aerial vehicle raises a high demand for the efficiency of propeller at low Reynolds numbers. An optimization method for low Reynolds number propeller is established by iterative optimizations of the sectional airfoils and the chord, pitch distributions in this paper. Different from the traditional method, each sectional airfoil is continuously optimized under the specific Reynolds number and lift coefficient which are updated with the iteration in the proposed method. Adopting this method, the propeller for an ultra-high-altitude unmanned aerial vehicle is optimized. And the result shows that the optimized propeller can achieve 3.6% higher efficiency than the propeller designed by the traditional Betz method at the cruising condition (Re≈4.0×104).