High Subsonic NLF Airfoil Design at Low Reynolds Number

We developed an optimization design approach which can be used to the high subsonic Natural Laminar Flow (NLF) airfoil design at low Reynolds number. The aerodynamic characteristics are evaluated by the γ-Re_θt transition model, and a modified CST method based on the disturbing CST basis function is introduced in the airfoil parameterization. After that, we build up the optimization system which employs the MCPSO (Multi-Groups Cooperative Particle Swarm Algorithm) as the search algorithm, and then apply the optimization methodology to the design of a propeller tip airfoil. More specifically, the laminar separation bubble and transition location are controlled in the optimization process. Our simulation results indicate that the optimized distribution shows better ability to control separation position and reattachment position, and the pressure drag can be greatly reduced when the laminar separation bubble is weakened. We demonstrate that it is a reasonable design idea that the friction drag increment is proposed as a constraint condition. These design experiences can provide valuable reference data for the design of the high subsonic NLF airfoil at low Reynolds number.