Single-Point and Multipoint Aerodynamic Shape Optimization of High-Speed Civil Transport

Abstract

Single-point and multipoint aerodynamicshapeoptimization methods weredeveloped and demonstrated forthe designofanadvancedsupersonictransportsubjecttomanygeometricconstraints.Thestartingpointcone guration baseline was developed in support of the NASA High-Speed Research program using linear-theory-based methods and multidisciplinary system analyses. The single-point design method simulated the presence of nacelles and diverters at supersonic cruise by superimposing nacelles-on/nacelles-off pressure differences, from complete cone gurationanalyses,ontosingle-block-gridwing/bodycalculations.Themultipointdesignmethodusedamultiblock gridto treatthecompletecone guration,including nacelles/diverters, canard,empennage,and wing e aps/slats.Two forms of multipoint optimization were performed at Mach 2.4, 1.1, and 0.9: sequential (design at cruise followed by e ap and canard/tail incidence angle optimization at the two transonic conditions ) and multipoint (simultaneous design at the three e ight conditions via a composite objective function ). Euler-based optimization using a combination of the two methods achieved signie cant performance gains derived from the nonlinear effects. The single-point approach produced much of the improvement, lowering the appropriately weighted thrust coefe cient by 4.28 counts after trimming the full cone guration at the three design points. (A seven count drag reduction was achieved at cruise for the untrimmed vehicle. ) The sequential and multipoint methods achieved 6.03 and 7.55 counts of composite thrust reduction, respectively.