Aerodynamic Interaction Effects of wingtip-Mounted Propellers

Abstract

The study presents an aerodynamic analysis of the propeller–wing interaction effects for the wingtip-mounted propeller configuration. The influence of the initial parameters of the propellers, such as the radius, the pitch angle as well as the direction of rotation on the models aerodynamic characteristics, in particular, on the wing span-efficiency factor and the induced drag was determined. In this research a computational simulation of the wingtip flow field was implemented using two different computational models with two different Reynolds numbers.Flow field simulations over computational models with different combinations of initial parameters were performed by means of the computational aerodynamic methods (the panel-vortex method of symmetric peculiarities). The simulation showed a significant positive effect on the aerodynamic characteristics of the computational models due to wingtip-vortex attenuation and swirl recovery by the propeller slipstreams. Analysis of the wing performance pointed out that the aerodynamic benefit of the wingtip-mounted propeller was due to an increase of the effective span-efficiency parameter of the wing.The induced drag coefficients and wing span-efficiency factors of the computational models for different combinations of given initial parameters, such as propellers radius and pitch angles, as well as the direction of rotation are obtained. The dependences between the given initial parameters and the studied aerodynamic characteristics of the computational models are determined. It is established that the character of these dependencies is identical for both computational models with two different Reynolds numbers. The analysis of the obtained dependencies indicates that when the propellers pitch angle φ changes, the highest efficiency zone is observed, that is characterized by the maximum value of the derivative dλef/dφ. The range of expedient change of the propellers pitch angle is determined, as a consequence.The most of the results are presented by diagrams for both computational models. The results obtained are of practical significance and will be useful for the aircraft design, performed according to the studied aerodynamic scheme.