Application of Additive Manufacturing to Rapidly Produce High-Resolution Total Pressure Distortion Screens

Abstract

Detailed, accurate knowledge of interactions between embedded engines and inlet/ airframe-generated nonuniform flow profiles is essential for the successful design of robust integrated engine systems. In the absence of direct-connect experimentation, flow distortion patterns must be simulated by generating the nonuniformities with flow conditioning devices. Traditionally, wire screens installed on a supporting grid have been used to induce regions of steady total pressure distortions, utilizing sections of constant-porosity wire meshes assembled to form a complete screen. The design of wire screens that accurately reproduce steady total pressure distortions representing inlet-engine interactions is challenging because modern fluids and structures modeling approaches cannot be efficiently applied, resulting in numerous construction and testing iterations. Additive manufacturing methods (“rapid prototyping”) can be used to quickly and accurately produce distortion screens for testing of integrated inlet-engine systems. Rapid prototyping methods enable the production of unique screen geometries that are otherwise very difficult, impractical, or even impossible. A screen design method compatible with additive manufacturing methods that utilizes a hexagonal-element flow control grid composed of airfoil cross-sections is presented. Advantages of this new design and screen production method include improved aerodynamic and flow control features, a more durable structure, and greater design flexibility resulting in a more accurate reproduction of the desired distortion profile. Results of the design and fabrication of a prototype screen are presented.