Mechanisms and optimisations of 3D shock control bumps.

By using an efficient adjoint-based aerodynamic optimisation method, both the 2D and 3D bumps are optimised on an unswept wing with either a natural laminar flow aerofoil or a turbulent aerofoil. The mechanisms of the shock control bumps are analysed through pressure drag analysis, as well as wave drag analysis that uses a far-field method. It is shown that the bumps reduce both the wave drag and the form drag. Comparisons of the performance of these two types of bumps indicate that the 3D bump has an advantage over the 2D bump at lower-lift off-design conditions. A low-order geometrical model for the 3D bump is derived based on the correlations of the design parameters with respect to the strength and position of the original normal shock wave on the datum wing. A finite number of 3D shock control bumps are placed on a full 3D transonic swept wing. The designs of the 3D bumps have been optimised in advance on an infinite swept wing with a constant aerofoil section that is extracted from the midspan of a chosen 3D transonic wing. Further drag analysis exhibits the effects of the 3D bumps on the various drag components. The combined wing shape with 2D bump optimisations demonstrates the potential of designing a wing with low sweep angle. The feasibility of carrying out a large aerodynamic optimisation is demonstrated in the combined optimisation study of a BWB aircraft with 3D bumps.