Two-level aerodynamic shape optimization strategy based on three-dimensional CST modeling method

A new two-level aerodynamic shape optimization structure using a universal three-dimensional class shape transformation(CST)parameterization technology was presented for the geometry modeling and computational efficiency problem of complex configuration aircraft aerodynamic shape optimization. The original two-dimensional CST method was expanded to three-dimensions using B-spline instead of Bernstein polynomial and lateral profile function, and a full three-dimensional aircraft geometrical shape description forms was given based on components build-up technology. According to the characteristics of class function/shape function and B-spline, a two-level design space aerodynamic shape optimization method was introduced by dividing the design variable into global sizing parameter and local adjust parameter, which can save optimization time while keeping the original design space complexity as much as possible. The X-33 hypersonic aircraft optimization result shows that this method has advantages of less basal design variable, adjustable design variable, high geometrical shape expression ability and stable parametric process, and the two-level design space aerodynamic shape optimization method has the abilities of excellent design space exploration and high computational efficiency.