Application of the 3D multi-block CST method to hypersonic aircraft optimization

Applying a parameterization technique with fewer parameters and high fidelity improves the efficiency and accuracy of aerodynamic shape optimization. The class and shape transformation (CST) method is concise and efficient. Nevertheless, it is difficult to parameterize complex vehicle configurations using a unified CST method. This article presents a multi-block CST method after analyzing the mathematical description of the method, and this method joins adjacent surfaces smoothly and retains the good properties of the CST method. Modeling cases indicate that the multi-block CST method can reduce the number of design variables used to represent surfaces with uneven curvature distributions and can smoothly model various classes of surfaces. A system of aerodynamic shape optimization is developed based on the multi-block CST method, Pareto genetic algorithms and hypersonic aerodynamic engineering analysis, and the aerodynamic characteristics of a quasi-waverider wing-body vehicle are improved significantly after optimization. A novel configuration is also created using the optimization system. The optimization results indicate that the multi-block CST method, which involves fewer design variables and yields higher fidelity, is a powerful tool for aerodynamic shape optimization.