Natural laminar flow nacelle optimization design based on EFFD method

Aerodynamic shape optimization of natural laminar flow (NLF) nacelle was studied using extended free-form deformation (EFFD) technique. An parameterization method for nacelle section based on EFFD using Bernstein base functions was implemented. γ-θ transition model coupling with k -ε shear stress transport (SST) turbulent model was used for transition prediction. An optimization system for NLF nacelle design was established in combination with EFFD, a hybrid grid deformation method, Kriging surrogate model and an improved particle swarm optimization. Both flow-through nacelle and powered nacelle were optimized using the optimization system. Optimized flow-through nacelle maintained a laminar flow about 48% and its drag coefficient was 0.000 3 less than initial flow-through nacelle. Powered nacelle maintained a 41% laminar flow after optimization. These results indicate that the optimization system is applicable in NLF nacelle design.