Numerical investigation of unsteady fluid flow inside air cooling lines with tilted heat exchanger for electrified aero engines

Abstract

The cooling line is a critical subsystem in a high-power fuel cell based propulsion system for the next-generation of aircraft. Within such complex architectures, unsteady and turbulent flows are inevitable, often leading to substantial pressure loss penalties. As part of the Clean Aviation Joint Undertaking pro-ject FAME (Fuel Cell Propulsion System for Aircraft Megawatt Engines), this study presents the design and analysis of a cooling line geometry developed in cooperation with the overall aircraft design, featuring a rectangular inlet, a circular outlet, and an integrated tilted heat exchanger preselected from an in-house design configuration. The study focuses on capturing the unsteady flow behavior and pressure characteris-tics using three-dimensional Large Eddy Simulation (LES). The heat exchanger is modeled with a porous media approach based on the Darcy-Forchheimer equation [1], while the simulations are carried out using a self-adapted version of the pisoFoam solver, termed pisoTempFoam [2], to account for heat transfer. The flow is examined along three key regions: upstream, within, and downstream of the heat exchanger, enabling end-to-end pressure loss evaluation.