Flow visualisation over the low sweep unmanned combat aerial vehicle (UCAV) configuration

Abstract

Steady-state experimental and computational studies on a lambda planform low sweep MULti-DIsciplinary CONfiguration (MULDICON) Unmanned Combat Aerial Vehicle (UCAV) configuration with 53° blunt leading-edge sweep are presented. The experiments were carried out in Universiti Teknologi Malaysia Low-Speed wind Tunnel (UTM-LST), and the computational work was done using Ansys Fluent. The flow visualisation for experimental and computational was performed at 30 m/s corresponding to the Reynolds number of 4.50E+05, for the angle of attack, α = 5°, 10°, 15°, 20°. Surface flow visualisation results confirmed the onset and progression of flow separation for low sweep lambda wing configuration. The experimental and the computational results demonstrated that the low sweep MULDICON wing lambda configuration is encountered with highly complex and nonlinear aerodynamic flow behaviour. Especially at high angle of attack (AOA), such as leading-edge vortices separation, vortex breakdown (suggested by strong shear layer region behind the leading-edge vortex) and shear layer reattachment that increases with the incidence increase. The computational results compared well to the experimental flow visualisation results.