Abstract
This paper presents the unsteady numerical simulation and analysis of the slipstream generated by distributed propellers on a solar-powered UAV using the CFD method based on structured/unstructured hybrid grids. Sliding mesh technology and a transition model are used for the numerical simulation of a NACA propeller and an Eppler 387 airfoil, the results of which are well compatible with the experimental data, proving the calculation method to be highly credible and accurate. Numerical simulations are run for configurations with the propeller in front of and behind the wing, and comparative analyses are conducted with a pure propeller and pure wing. The results suggest the existence of mutual disturbance between the propeller and the wing, as the propeller, either in front of or behind the wing, causes an increase in cyclical fluctuation of the wing’s lift, drag and nose-down moment. The wing, in return, gives rise to an increase in fluctuation of the propeller's pulling force, absorbing power and efficiency, with propeller oscillation being triggered by the discontinuity of the flow field. The configuration with the propeller posed behind the wing is proven to be of smaller disturbance to the whole system.
