Aerodynamic Analysis of the Ducted Fan for a VTOL UAV in Crosswinds

Abstract

An aerodynamic analysis of a ducted fan for vertical take-off and landing unmanned aerial vehicles was performed using computational simulation. A commercial computational fluid dynamics tool was used to solve the Reynolds-averaged Navier-Stokes equations. The calculated results were validated in the subsonic wind tunnel at Hanyang University. The objective of this study is to investigate the aerodynamic performance of a ducted fan in crosswinds. The thrust, normal and side forces of the ducted fan are affected by the velocity magnitude and in-flow angle of the crosswind. The pitching moment of the ducted fan is significantly influenced by the crosswind due to asymmetric lift force created by the difference in suction velocity magnitude on the duct lip. Flow separation at the duct lip occurs under hovering and crosswind conditions. The inlet flow fields of the ducted fan are distorted by the duct lip separation. In conclusion, to improve the stability of the ducted fan, the pitching moment must be reduced.