Studies on the Effect of Jet on Change in Airfoil Profile Based on a Hybrid-LES Model

Abstract

Recent aircraft morphing program envisions an aircraft without conventional control surfaces. Instead of moving control surfaces, the vehicle control systems may be implemented with a combination of propulsive forces, micro-surface-effectors, and fluidic devices dynamically operated by an intelligent flight control system. In the present work, first of all, the accuracy of a (RANS/LES) hybrid turbulent model, developed by the author is verified by applying it to predict the experimental drag and lift coefficient for (NACA4412) airfoil. Finally, the work described in this paper focused on the aerodynamic virtual shaping of an (NACA0012) symmetric airfoil at zero angle of attack, using only a thin jet without additional fixtures. The effects of virtual shaping are investigated systematically with thin jet actuation at different chordwise locations, and different ratio of jet and free-stream velocity. The jet was used to alter the aerodynamic shape of the considered symmetric airfoil with a purpose to enhance lift and/or to reduce drag. The virtual shape change is indicated by the formation of a small stationary re-circulating flow region next to the surface, which displaces the local streamlines sufficiently to modify the local pressure distribution. The effect is similar to that caused by a positive angle of attack to produce an overall lift change.