Session: 04-30 Hydrogen III

Submission Number: 176760

Effect of Additively Manufactured Wall Lattice Structures on Flashback Limits in a Hydrogen Jet Flame Combustor 

The establishment of hydrogen as a carbon-neutral energy source for gas turbine combustion is still challenged by flame flashback. Recent investigations have demonstrated that increasing the axial velocity of the unburnt gas mixture entering the combustor and hydrodynamically anchoring the flame within the jet shear layer provides a promising way to mitigate flame flashback. However, this often requires complex burner geometries to optimize the inflow conditions in order to reduce flashback propensity or emissions achievable only through additive manufacturing. This development, in turn, demands for printable burner materials associated to changes in physical properties.

In the present study, the flame flashback behavior of a jet flame combustor manufactured using selective laser–melting (SLM) is systematically investigated and compared to a conventionally manufactured reference burner. The SLM versions incorporate targeted design modifications intended to improve flashback resistance, enabled by the geometric freedom of additive manufacturing. For these modifications, the inner wall of the mixing duct is equipped with body-centered cubic (BCC) lattice structures. To assess the specific influence of these modifications, the geometric parameters of the lattice structure are varied by volume fraction, strut diameter, and axial position within the duct. All experiments are conducted under atmospheric conditions using pure hydrogen as fuel. The operating range covers a wide range of equivalence ratios across moderate Reynolds numbers between 9,000 and 12,000.

Flashback maps are obtained for each wall configuration to determine the respective operating limits. To quantify the influence of the mixing duct modifications on the flow field and flame topology, particle image velocimetry (PIV) and OH* chemiluminescence flame imaging are employed. The averaged flow fields show only minor effects from the wall modifications, which is intentional in order to preserve the general flow characteristics at each configuration. Further inside on the flashback behavior is provided by SPOD analysis of the flame dynamics complemented by pressure and temperature measurements inside the mixing duct. The present study shows that incorporating porous media in the combustor can mitigate flashback. As the main driver for this effect, the wall cooling by unburnt mixture entering the lattice structure is identified.

Presenting Author: Alexander Jaeschke Technische Universität Berlin

Presenting Author Biography: Mr. Jaeschke earned his master's degree in engineering science at the Technical University of Berlin. After working on a gas turbine burner prototype together with MAN Energy Solutions, he is currently working on the DFG project ENERGIZE, which includes the study presented here.

Authors:

Alexander Jaeschke Technische Universität Berlin
Thomas Ludwig Kaiser Technische Universität Berlin
Lukas Melzig Technical University of Munich TUM School of Engineering and Design Institute for Machine Tools and Industrial Management (iwb)
Michael Friedrich Zaeh Technical University of Munich TUM School of Engineering and Design Institute for Machine Tools and Industrial Management (iwb)
Kilian Oberleithner Technische Universität Berlin
Christian Oliver Paschereit Technische Universität Berlin