STUDY ON THE EFFECTS OF PROPLET GEOMETRIC PARAMETERS ON THE AERODYNAMIC CHARACTERISTICS OF HIGH-ALTITUDE PROPELLER

Propeller is an important part of high-altitude airship propulsion system operating at low Reynolds number, which makes its aerodynamic performance, especially efficiency, influences the overall design of airship a lot. This paper intends to increase the efficiency by adding two different kinds of proplet, and a trade study of proplet geometric parameters is performed. A new parametric method of proplet geometry is developed. Reynolds Averaged Navier-Stokes (RANS) equations are adopted to examine the performance of baseline and propeller with proplet. And a power matching method developed in previous study is used to compare the efficiency under the same shaft power. The results show that proplet can increase the aerodynamic efficiency of high-altitude propeller. The upward-bend proplet can increase more aerodynamic efficiency than downward-bend proplet with the same geometric parameters by 0.7% in average. Height of proplet, incline angle and twist angle of proplet tip have prominent effect on efficiency. As the incline angle increasing, the efficiency can increase nearly 1.2% at most. Some of the geometric parameters of different kind of proplet have opposite influence as the values change.