Aerodynamics properties and design method of high efficiency-light propeller of stratospheric airships

The low density of stratospheric air and small flight speed of airship bring certain difficulty to the aerodynamic design of stratosphere airship propeller. This paper firstly analyzes characteristics of flow around the propeller for an airship in atmospheric environment and the influence of the propeller outlet flow angle to sectional efficiency, then discusses the principle and the method of choice in geometry parameter of the propeller with the equal Re number and the equal stress principle. To specially avoid the appearance of laminar separation bubble (lower the efficiency), we adopt the airfoil with the low Reynolds Number and high lift in the design and present a three-blade propeller of composite materials with the variable-speed and fixed-pitch according to the design criteria of the airship propeller. The detail specification of the propeller is: the diameter D=6500 mm, propeller actual factor 62.3, maximum width 516 mm, and propeller pith angle 32.80. The paper also evaluates the aerodynamics performance in detail with the strip theory.