A method has been developed to efficiently implement supersonic aerodynamic predictions from Euler solutions into a highly constrained, muItidisciplinary design optimization of a High-Speed Civil Transport. The method alleviates the large computational burden associated with performing computational fluid dynamics analyses through the use of variable-complexity modeling techniques, response surface (RS) methodologies, and coarse-grained parallel computing. Using information gained from lower-fidelity aerodynamic models, reduced-term RS models representing a correction to the linear theory RS model predictions are constructed using Euler solutions. Studies into 5-, 10-, 15-, and 20-variable design problems show that accurate results can be obtained with the reduced-term models at a fraction of the cost of creating the full-term quadratic RS models. Specifically, a savings of 255 CPU hours out of 392 CPU hours required to create the full-term RS model is obtained for the 20-variable problem on a single 75-MHz IP21 processor of a Silicon Graphics, Inc. Power Challenge.
Nomenclaturec jk -response surface model coefficients g(x) = vector of optimization constraint values K = drag polar shape parameter m = number of design variables N = number of points used to evaluate response surface model error n = number of terms in the response surface model n p -number of processors used on a parallel computer Design Center for Advanced Vehicles. p = number of experimental design points q = number of candidate sample sites R LE = leading-edge radius parameter ffus, = fuselage radius at /th axial location 5 LE/ = inboard leading-edge length s TEj = inboard trailing-edge length (//c)break = thickness-to-chord ratio at leading-edge break (tlc\ ool = thickness-to-chord ratio at wing root 0/c) tip = thickness-to-chord ratio at wing tip WC-TOGW = corrected takeoff gross weight Wfue, = fuel weight WTOGW = takeoff gross weight Wwing = wing weight x = ra-dimensional vector of design variable values (*/c)max-r = chordwise location of maximum thickness Xj = jth design variable *max = vector of upper bounds on design variable values *min = vector of lower bounds on design variable values v = observed response value y = predicted response value Vnac = spanwise location of inboard nacelle AC Do = correction to linear theory value of the drag polar shape parameter A^f = correction to linear theory value of the drag polar shape parameter AW^i = correction to fuel weight A;y nac = distance between nacelles A LE/ = inboard leading-edge sweep angle ALE O = outboard leading-edge sweep angle A T E 7 = inboard trailing-edge sweep angle