Session: 04-43 Hydrogen Emissions III

Submission Number: 175733

The Development, Testing and Analysis of a Hydrogen Swirled Micromix Injector for Aerospace Applications 

In order to reduce the environmental impact of aviation, it is necessary to change the fuels used. Conventional aircraft engines running on fossil kerosene are responsible for emitting roughly 2% of the global carbon dioxide emissions and further contribute to environment degradation through the emission of nitrous oxides (NOx), soot and the formation of contrails. One option to reduce the environmental impact of aviation is through the introduction of hydrogen as an alternative fuel.

An important technological element that needs to be developed is the safe, and clean use of hydrogen aboard an aircraft that minimises the impact of the change of fuels on the performance of the complete system. Arguably, the use of a hydrogen fuel cell guarantees that the environmental impact of a hydrogen aircraft would be minimised, however at the scale of aircraft in the regional to SMR (small-to-medium range) market, a fuel cell is likely to be too heavy to compete with the solution proposed in this work: hydrogen combustion.

To justify hydrogen combustion, it is nevertheless important that NOx emissions are minimised, a problem for a fuel that, due to its higher adiabatic flame temperature, is predisposed to producing more NOx than traditional fuels. Safran Tech has been investigating different Low NOx solutions for the combustion of hydrogen since its involvement in the ENABLE H2 European project that investigated the use of micromix designs in aircraft engines. In the more recent European project HESTIA and the French funded project H2TECH, this micromix technology has evolved to produce a swirled micromix design that has recently been tested on ONERA high pressure high temperature MICADO test facility. The conducted tests involved the characterization of the flame structure and dynamics using optical diagnostics (OH-PLIF, OH* high speed chemiluminescence), and of the combustion quality (NOx emission and combustion efficiency). These characterizations were performed for different equivalence ratio at pressure up to 25 bar.

This design exhibits excellent stability characteristics, low air-side pressure drop, pilotless operation, a compact flame, a form factor similar to traditional kerosene injectors and with NOx emissions equivalent to 30 % of CAEP8, lower than the best kerosene injectors currently in production. This paper explores the development of this injector; the key experimental results and certain comparisons made with 3D numerical simulations of differing levels of fidelity including adiabatic and thermally coupled RANS and LES.

 

Presenting Author: Nicholas Treleaven Safran Tech

Presenting Author Biography: Nicholas is a research engineer at Safran Tech developing combustion systems.

Authors:

Nicholas Treleaven Safran Tech
Florian Monnier Ariane Group
Teddy Bouteveille Ariane Group
Sylvain Petit ONERA
Guillaume Pilla ONERA