A method to efficiently introduce supersonic drag predictions from
computational fluid dynamics (CFD) calculations in a
combined aerodynamic-structural optimization of a High-Speed Civil
Transport (HSCT) is presented.
To achieve this goal, the method must alleviate the large computational
burden associated with performing CFD analyses and reduce the
numerical noise present in the analyses.
This is accomplished through the use of response surface (RS)
methodologies, a variation of the variable-complexity modeling (VCM)
technique, and coarse grained parallel computing.
Variable-complexity modeling allows one to take advantage of the information
gained from inexpensive lower fidelity models while maintaining the
accuracy of the more expensive high fidelity methods.
The utility of the method is demonstrated on HSCT design problems
of five, ten, fifteen, and twenty design variables.
Motivation for including CFD predictions into the HSCT optimization
comes from studies detailing the differences in supersonic aerodynamic
predictions from linear theory, Euler, and parabolized Navier-Stokes (PNS)
calculations for HSCT configurations.
The effects of these differences in integrated forces and distributed loads
on the aircraft performance and structural weight are investigated.
These studies indicate that CFD drag solutions are required for accurate
HSCT performance and weight estimates.
Response surface models are also used to provide useful information to the
designer with minimal computational effort.
Investigations into design trade-offs and sensitivities to certain design
variables, available at the cost of evaluating a simple quadratic polynomial,
are presented.
In addition, a novel and effective approach to visualizing high dimensional,
highly constrained design spaces is enabled through the use of RS models.
NOTE: An updated copy of this ETD was added in July 2012 after there were patron reports of problems with the original file.
