Static aeroelastic characteristics of circulation control wings

Abstract

Circulation control airfoils can develop lift coefficients far in excess of conventional airfoils through the use of tangential blowing and thus have potential applications for V/STOL aircraft. The static aeroelastic effects of circulation control on swept wings are examined using two analytical models: a simple two-degree-of-freedom model with linearized aerodynamics and an elastic beam model coupled with nonlinear two-dimensional airfoil data. The static divergence instability and a circulation control reversal phenomenon are investigated through the use of lift and control effectiveness ratios. Effects of wing sweep angle, elastic axis location, blowing level, and spanwise blowing distribution are presented. Linear, nonlinear incompressible, and nonlinear compressible aerodynamic representations are compared. Significant differences were observed between the linear and nonlinear aerodynamic results. Tailoring of the spanwise blowing distribution is shown to be an effective means of improving undesirable aeroelastic characteristics. The results indicate that the aeroelastic behavior of circulation control wings can be quite different from that of conventional wings.