Noisy Aerodynamic Response And Smooth Approximations
In HSCT Design.
5th AIAA/USAF/NASA/ISSMO Symposium on
Multidisciplinary
Analysis And Optimization
September 7-9, 1994
Panama City Beach, Florida
Giunta,A.A., Dudley,J.M., Narducci,R., Grossman,B.,
Haftka,R.T., Mason,W.H. and Watson,L.T.
Abstract
Convergence difficulties were encountered in our recent efforts toward
a combined aerodynamic-structural optimization of the High Speed Civil
Transport (HSCT). The underlying causes of the convergence problems
were traced to numerical noise in the calculation of aerodynamic drag
components for the aircraft. Two techniques were developed to
circumvent the obstacles to convergence. The first technique employed a
sequential approximate optimization method which used large initial
move limits on the design variables. This helped dislodge the optimizer
out of the local minima in the design space created by the noisy drag
data. The second method utilized response surface methods to
construct smooth approximations to the noisy data. The response
surfaces were formed by analyzing several individual HSCT
configurations and then fitting polynomial functions to selected
objective function data. A simplified example design problem was used
to demonstrate the response surface technique and to investigate
various other issues relating to the construction of the response
surfaces.
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knill@aoe.vt.edu