Aerodynamic Duct Shape Optimization for Lifting and Propulsion of a Vertical Take-off and Landing Unmanned Aerial Vehicle

Abstract

An aerodynamic analysis of the ducted fan for vertical take-off and landing unmanned aerial vehicles was performed using computational simulation. The commercial computational fluid dynamics tool was used to solve 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 the 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 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. The pitching moment decreases by results of design optimization for cross-section of ducted fan. In conclusion, to improve the stability of the ducted fan, the pitching moment must be reduced. The design optimization was performed to improve the aerodynamic performance. OLHD method used to select the important computational points. Kriging surrogate model adopted the interpolation of the DOE results. The optimized result was predicted using genetic algorithms. As a results of optimization, the pitching moment was reduced.