An Analysis of Increasing Thrust of an Air Propeller Through Additional Lift Surface

Air propellers used in small scale unmanned aircraft operate at low Reynolds numbers. The aerody-namic force occurring on the blade when the air propeller is in operation is of variable nature. It is observed that for Reynold numbers below 5⋅105 flow separation can occur on some sections of the propeller surface. To deal with the problem, increase the lift on the blade and therefore, reduce the turbulence boundary level, a new design called bi-blade propeller is developed and patented. This design features an additional blade above the main one. Using ANSYS Fluent, samples of the bi-blade propellers were investigated to determine the positions where the inductive resistence and the turbulence boundary level decreased, and the lift increased when the air propeller was in operation. A comparison study was conducted in laboratory conditions to investigate static thrust of the bi-blade propeller on a test bench at 2000–4500 мин–1. The bi-blade propeller was compared with a conventional propeller.