Automated Diffuser Shape Optimization based on CFD Simulations and Surrogate Modeling

An approach for the optimization of laminar flow in diffusers is presented. The goal in our optimization process is to maximize diffuser performance and, in this way, pressure recovery by optimizing the geometry. Our methodology is the optimization through wall contouring of a given two-dimensional diffuser length ratio. The developed algorithm uses the CFD software: Fluent for the hydrodynamic analysis and employs surrogate modeling and an expected improvement approach to optimization. The non-uniform rational basic splines (NURBS) are used to represent the shape of diffuser wall with three to nine design variables, respectively. The framework is assisted by the construction of Kriging model, for the management of the problem. The CFD software and the Kriging model have been combined for a fully automated operation using some special control commands on the MATLAB platform. In order to seek a balance between local and global search, an adaptive sample criterion is employed. The optimal design exhibits a reasonable performance improvement compared with the reference design.