Stowability Constraint Within a Two-Dimensional Aerodynamic Optimization Method

Abstract

M ULTIDISCIPLINARY constraints were developed for a twodimensional gradient-based aerodynamic optimization method [1–4]. Thickness constraints [4] and a cross-sectional area constraint [5–7] were added to maintain structural integrity and to optimize for fuel volume, respectively. Curvature constraints [8] were added to control geometric oscillations. This work focuses on implementing a stowability constraint within a high-lift configuration. Significant work has been done on high-lift design optimization. Lin and Dominik [9,10] have focused on designing new high-lift components using both computational methods and wind-tunnel testing. Kim et al. [11] have discussed an adjoint-based method to optimize two-dimensional airfoils using the flap overlap, gap, and shape as design variables. Nemec and Zingg [3] have also discussed results for optimizing high-lift examples using the gap and overlap as design variables. These are necessary, but not the only important, components for the design of an airfoil, especially for high-lift design. As stated by Mathews [12], “The design of high lift systems cannot be based solely upon maximum aerodynamic performance but is constrained by weight, cost, ease of manufacture, maintainability, reliability and themechanics of the flapmovement.” Van Dam et al. [13] developed a methodology that merges aerodynamic data with kinematic analysis. This methodology allows a general database of aerodynamic performance to be integrated directly into the mechanism design and analyzed. This Note illustrates how a stowable design space can be created that allows the designer to generate a flap shape that will be stowable. This design space is created by using the path that the flap will take during extension or retraction, which is determined fromkinematic analysis. The stowability constraint will provide the designer with another option in high-lift design. This Note only focuses on adjusting the stowable flap shape by having the flap shape as a design variable, but this could easily be incorporated with the flap gap and overlap as design variables.