In this work we focused on the aerodynamic drag caused by a folding blade propeller while in the folded position, on a glider model airplane. The drag was calculated using computational fluid dynamics, because of the inability to perform accurate measurements directly on the glider model. Calculations were performed for the part of the fuselage ahead of the wing only.
Calculations of five different geometries were performed: a clean fuselage, a fuselage with a standard folding propeller (with and without the presence of a cooling duct for the motor) and a fuselage with a modified folding propeller, which fits the fuselage better (with and without the presence of a cooling duct for the motor).
An unstructured mesh was used, calculations for different mesh extent and density were performed in order to ensure a mesh independent solution. When performing calculations for the clean fuselage, a laminar flow was assumed. While performing calculations for the fuselage with a propeller, the Spalart-Allmaras turbulence model was used. All calculations were performed using the Ansys Fluent software.
For the estimation of the total drag of the model airplane, measurements were performed using a GPS system coupled with a barometric altitude sensor.
We found out that the presence of a propeller increases the glider's drag by almost 2%. The propeller's shape also influences the amount of drag. The standard propeller creates more turbulence. The difference in drag caused by the two propellers is about 0,1%. Our results indicate that the cooling duct decreases the drag.
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