Hybrid methods for inverse aerodynamic design

This thesis describes a novel hybrid approach for the multipoint inverse design of airfoils for complex aerodynamic systems. In this approach, an inverse design method for single-element airfoils is coupled with an analysis module for the complex system. The airfoils that comprise the complex system are generated in isolation using the single-element airfoil inverse design method. The analysis module is then used to obtain the aerodynamic characteristics of the resulting complex system. Using a multidimensional Newton iteration, the design variables associated with the generation of the airfoils in isolation are adjusted to achieve desired aerodynamic characteristics on the complex system.; As the thesis demonstrates, changes in velocity distributions for an airfoil in isolation are very similar to the changes for the same airfoil as a part of a more complex system. This similarity enables (1) the use of the isolated airfoil velocity distributions as design variables to achieve the desired aerodynamics on the complex system and (2) the computation of sensitivities for the Newton iteration during the design of the airfoils in isolation rather than through repeated function evaluations of the analysis module. These features result in a unified hybrid approach that not only is rapid and interactive, but also enables easy integration of different analysis modules in the design method.; In this thesis, the hybrid approach has been applied to the development of inverse methods for the design of (1) multi-element airfoils for multipoint velocity and boundary-layer prescriptions and (2) airfoils to obtain desired multipoint velocity distributions on three-dimensional wings and complex juncture regions. These methods are discussed in detail. Several examples are presented to demonstrate the methods. Finally, the potential of the hybrid design approach for application to the design of other systems such as airfoils with plain flaps and airfoils for wing-fuselage junctures is presented.