Aerodynamics of short intake at high incidence

Abstract

This work assesses the aerodynamics of a short aero-engine intake for a new rig that is planned to be tested at the Large Low-Speed Facility of the German Dutch Wind Tunnels (LLF-DNW) in 2025. A range of computations were performed to assess whether the expected aerodynamics in this arrangement encompass the envisaged range of flow field characteristics of the equivalent isolated configuration. The effect of massflow capture ratio and angle of attack are investigated. In addition, an intake flow separation taxonomy is proposed to characterise the associated flows. The wind tunnel analysis is based on two different modelling approaches: an aspirated isolated intake and a coupled fan–intake configuration. The coupled configuration uses a full-annulus model with a harmonic mixing plane method. Across the range of operating conditions with changes in the massflow capture ratio and angle of attack, there are attached and separated flows. The main separation mechanisms are diffusion-driven and shock-induced, which shows the different aerodynamics that may be encountered in a short intake. Overall, this work provides an initial evaluation of the aerodynamics of the new fan/intake test rig configuration, provides guidance for wind tunnel testing, and lays a foundation for subsequent unsteady coupled fan–intake studies.