Inverse aerodynamic design for DEP propeller based on desired propeller slipstream

Considering the multi-propeller characteristics of DEP (distributed electric propulsion) configuration, the lift-to-drag ratio of the wing is improved by optimizing the slipstream of the propeller, rather than changing the chord length and twist distribution along the span of the wing. In this paper, a propeller inverse design method based on slipstream characteristics is developed. In the case of propeller design, only a few general parameters and induction factor distribution form have to be prescribed and the design procedure returns the propeller geometry in terms of chord-length and blade-angle distributions along the radius. Propellers with different induced velocity distributions are designed based on this method. It is found that the propellers with larger induced velocity near the hub can improve the lift-to-drag ratio of the wing without changing the parameters of the wing, drag decreases by 12.32% and the lift-to-drag ratio of the wing with single propeller increase by 16.10%, respectively. A 27.12% drag reduction and 43.21% lift-to-drag ratio improvement can be obtained when three propellers are used.