Automated Optimization of a Double S-Shaped Inlet for Minimum Loss and Reduced Sight onto the Engine Face

Abstract

Designing propulsion systems for both military vehicles and potentially new transport aircraft concepts with highly integrated engine installation requires to handle an increasingly complex flow structure while respecting multiple constraints on feasible inlet geometries by signature and installation needs. Design of these propulsion systems will be even more challenging due to the severe interaction of the compressor performance with its distorted inflow conditions. The authors intend to develop tools and optimization strategies, which allows an integrated, optimal design of both the inlet and the low pressure compressor. Based on experience in the field of compressor design and optimization, the current work constitutes a first step towards incorporating the inlet into design and optimization processes. A geometry modeling and mesh generation program was developed for parameterization of a wide range of simple to highly complex duct shapes. In the scope of this work a generic, double S-shaped inlet has been automatically optimized. The duct shape in between a rectangular inflow and circular engine fac was optimized both with respect to pressure loss and the portion of direct sight on the engine face (“visibility”), which are highly negatively correlated goals. Acceleration techniques by response surfaces have been applied to deal with the high number of 66 free design parameters. Optimized inlet geometries show significant improvement of pressure loss and flow uniformity at the engine face.