MULTIDISCIPLINARY OPTIMIZATION OF A SUPERSONIC TRANSPORT USING DESIGNOF EXPERIMENTS THEORY AND RESPONSE-SURFACE MODELING

The presence of numerical noise in engineering design optimisation pro blems inhibits the use of many gradient-based optimisation methods. Th is numerical noise may result in the inaccurate calculation of gradien ts which in turn slows or prevents convergence during optimisation, or it may promote convergence to spurious local optima. The problems cre ated by numerical noise are particularly acute in aircraft design appl ications where a single aerodynamic or structural analysis of a realis tic aircraft configuration may require tens of CPU hours on a supercom puter. The computational expense of the analyses coupled with the conv ergence difficulties created by numerical noise are significant obstac les to performing aircraft multidisciplinary design optimisation. To a ddress these issues, a procedure has been developed to create noise-fr ee algebraic models of subsonic and supersonic aerodynamic performance quantities, for use in the optimisation of high-speed civil transport (HSCT) aircraft configurations. This procedure employs methods from s tatistical design of experiments theory and response surface modelling to create the noise-free algebraic models. Results from a sample HSCT design problem involving ten variables are presented to demonstrate t he utility of this method.