Decarbonized Aviation: ONERA Tests Hydrogen Leaks in PyCoFiRe
Inaugurated in May 2025, this unique infrastructure worldwide is dedicated to the safety of decarbonized aviation. Entirely focused on studying the fire behavior of composite materials, it now hosts its first experiments, centered on a case study involving hydrogen.
PyCoFiRe is designed to recreate and analyze, under representative conditions at a 1:1 scale, fires within the engine compartments of single-aisle commercial aircraft.
Between March and July 2025, an initial measurement campaign was conducted to evaluate the distribution of a lightweight fuel following a leak, as part of the European project Clean Aviation CONCERTO. The center is exploring new avenues for compliance measures for the certification of new propulsion technologies, particularly the use of hydrogen. In partnership with Safran Aircraft Engines, the work involves, additionally, modeling and testing a hydrogen leak within an engine compartment.
The experimental phase is conducted on the PyCoFiRe FAN test bench, chosen for its 1:1 scale to magnify diffusion phenomena. For safety reasons, hydrogen is replaced by helium, an inert gas with no explosive risk for the setup. The goal is to perform volumetric concentration measurements of helium to determine its distribution under various ventilation conditions of the assembly and different helium injection configurations, especially to assess possible gas accumulation zones.
The installation, initially designed to reproduce realistic thermal threats, has been specifically enhanced for these tests. A system for controlling the injected leak rate was devised and manufactured by MPM, in collaboration with ONERA. It is connected to an injection lance set up in multiple positions and orientations within the test duct.
A gas analyzer continuously samples helium at 24 spatially distributed points within the test duct, enabling the identification of potential critical zones. Twenty-two configurations were tested, varying parameters such as ventilation and temperature within the test duct; and the position, orientation, and flow rate of the helium leak.
In parallel, simulations conducted with the CEDRE code, developed at the Department of Multi-Physics for Energy, help better understand the flow dynamics and evaluate the model?s capacity to estimate helium distribution within the bench, as well as the associated fire risk.
This facility benefited from financial support from the European Union, the European Regional Development Fund (ERDF), and the Occitanie / Pyrénées-Méditerranée region. The CONCERTO project is funded by the European Union?s Clean Aviation Joint Undertaking (CAJU) program.
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