Optimization design for HLFC wings considering influence of suction distribution

Regarding the issue about Hybrid Laminar Flow Control (HLFC) wings aerodynamic design, we establish an aerodynamic optimization design system by directly coupling the CFD method with the optimization technologies including the Free Form Deformation (FFD) parameterization, the Radial Basis Function (RBF) dynamic mesh method based on compact support radial basis function, and the improved differential evolution. The transition prediction model is e^N method. For the infinite span swept wing, the system proposed is used to do single-point design, and multi-point robust designs which consider the variation of lift coefficients and Mach numbers. Optimization results show that the best pressure distribution of HLFC wings has a low negative pressure peak at the leading edge, followed by a gently adverse pressure gradient. Then, just behind the adverse pressure gradient, there exists a suitable favorable pressure gradient. Compared with the original model, the transition location of the single-point design result, which has a good pressure distribution, is delayed from 2% of the chord to the chord length of 57%, but the suction control strength is only half of that of the original model. Multi-point design results indicate that increasing the strength of suction control, especially at the beginning and end of the suction control region, is conducive to improving the robustness of HLFC wings. When the Mach number is in the range of 0.77-0.79 and the lift coefficient is in the range of 0.53-0.65, the multi-point design results can maintain laminar flow region over the chord length of 37%.