Aerodynamic Shape Optimization Methods

Although fast and accurate in creating aerodynamic shapes compatible with the specified surface pressure distribution, the inverse shape design methods create configurations that are not optimal even at the design operating conditions [163], [164]. At off design conditions, these configurations often perform quite poorly except when the specified surface pressure distribution, if available at all, would be provided by an extremely accomplished aerodynamicist. When using inverse shape design methods, it is physically unrealistic to generate a 3-D aerodynamic configuration that simultaneously satisfies the specified surface distribution of flow variables, manufacturing constraints (smooth variation of a lifting surface sweep and twist angles, smooth variation of its taper, etc.) and achieves the best global aerodynamic performance (overall total pressure loss minimized, lift/drag maximized, etc.). The designer should use an adequate global optimization algorithm that can utilize any available flow-field analysis code without changes and efficiently optimize the overall aerodynamic characteristics of the 3-D flight vehicle subject to the finite set of desired constraints. The constraints could be purely geometrical or they can be of the overall aerodynamic nature (minimize overall drag for the given values of flight speed, angle of attack and overall lift force, etc.). These objectives can only be met by performing an aerodynamic shape constrained optimization instead of an inverse shape design.