A New Circular Section Control for Streamwise Profiles in Aeroengine Nacelle Cowl Design and Optimization

Nacelle cowl design is dedicated to generating a three-dimensional surface with optimal drag performance. Most previous approaches focused primarily on the design method driven by streamwise profiles, which introduced no additional aerodynamically significant variables into the geometric constraints. Therefore, to explore more design spaces for drag reduction of the nacelle cowl, this paper proposes a design refinement method by adding a circular curve that passes through the locations of maximum thickness of given streamwise profiles at various angles toward the nacelle axis, which are regarded as the design variables. A proof-of-concept study was modeled using a combination of computer aided design, Latin hypercube sampling, computational fluid dynamics (CFD) simulation using Reynolds-averaged Navier-Stokes equations closed by a k-? shear stress transport model, and a kriging surrogate model, in order to search for the optimal solution in design space. The result of optimization shows that the aerodynamic performance of the nacelle cowl was optimized significantly, with a 28.50% drag coefficient reduction with only three angular variables taken to create the design space, illustrating the feasibility of the proposed approach.