First hydrogen tests in transparent combustion chamber at DLR

First hydrogen tests in transparent combustion chamber at DLR
by Robert Schreiber
Berlin, Germany (SPX) Jul 14, 2023

The German Aerospace Center and General Electric Aerospace (GE) have taken a significant step forward in the development of hydrogen-fueled aviation technology. In a first-of-its-kind endeavour, these organizations have examined the combustion of pure hydrogen under practical aircraft engine operating conditions.

This initiative is a part of a broader, four-year research collaboration, aimed at fostering low-emission combustion technologies and refining optical measurement methodologies. The research was conducted at the DLR Institute of Propulsion Technology in Cologne and formed a part of the overall effort to convert a GE Passport engine to function with hydrogen. This engine will be subsequently incorporated into the Airbus ZEROe flight demonstrator, marking a significant milestone in Airbus's plan to create the world's first hydrogen-powered commercial aircraft by 2035.

Hydrogen, despite its potential as a clean energy source, poses unique challenges in the realm of aviation, primarily due to its combustion behaviour, which is vastly different from conventional fuels like kerosene. This recent test signifies a pivotal moment as it allows researchers to explore hydrogen combustion in an environment that mimics realistic operating conditions. The state-of-the-art infrastructure at DLR, paired with a globally unique blend of experimental research facilities, expertise in high-pressure combustion chambers, and cutting-edge laser-optical measurement methods, has made this endeavour possible.

In the past, hydrogen tests have been conducted under atmospheric conditions. However, this new collaboration between DLR and GE Aerospace has pushed the boundaries, implementing high-pressure tests to understand how hydrogen flames behave under various operating conditions. The results of these tests are crucial for collecting valuable data and understanding if the combustion chamber can endure extreme thermal loads.

Commenting on the cooperation, Bertram Janus, Acting Director of the Institute of Propulsion Technology and Head of the Combustor Department, stated, "In very good cooperation and friendly collaboration, a new measurement system has been developed especially for this project." He stressed the importance of mimicking realistic operating conditions for hydrogen combustion in aircraft gas turbines, given the unique characteristics of the fuel.

The data collection was facilitated by a special optical access, with large quartz windows providing unprecedented insights into the combustion chamber. This enabled the researchers to characterise the combustion behaviour and the reacting flow within the chamber, utilising the laser-optical measurement methods developed at the Institute.

Christian Willert, Head of the Engine Measurement Systems Department at the DLR Institute of Propulsion Technology, explained how the optical measurements enabled instantaneous detection of the reaction and heat release zones without affecting the combustion chamber flow. He also noted the role of flow field measurements in tracking the movement of the air-hydrogen mixture and reaction products through the combustion chamber.

The results of these tests, summarised by Thomas Ripplinger, Team Leader for Thermal and Combustion Systems at GE Aerospace Advanced Technology, will help assess whether the burner meets expectations or if changes need to be made to the development and design tools.

DLR and GE Aerospace plan to conduct further tests in the future under more application-oriented conditions.

These tests form a part of the EU HYdrogen DEmonstrator for Aviation (HYDEA) project, which aims to develop a propulsion system with zero carbon-dioxide emissions, based on the direct combustion of hydrogen, by 2026. The results of HYDEA are expected to be a significant milestone in the research of ZEROe technologies initiated by Airbus in 2020.