For future low emission power generation, combustion of hydrogen in novel gas turbine systems represents an attractive alternative when the production of the fuel can be realized even by renewable energy sources. The development of new combustor technologies means an essential task when Dry-Low-NOx (DLN) Hydrogen combustion is applied to industrial gas turbines as its fast reaction behavior with hot flame regimes exceeds NOx levels and leads to a severe flashback risk.
On that account the “Micromix” principle has been successfully developed and tested in recent years by injecting hydrogen fuel perpendicular into air cross-flow and burning it in a multitude of miniaturized diffusion flames. Due to a decreased flame front, significant reduction of NOx emissions correlates with a shorter residence time in the hot gas area. By the use of steady-state RANS simulations, a systematic design exploration has been performed, to identify the complex relation between design parameters and their impact on the burnerfs performance.
For this campaign, two different combustor designs were measured under atmospheric pressure at the combustion chamber test rig of Aachen University of Applied Science. The combustion performance and low NOx behavior of these designs were evaluated from part load to overload conditions. The validation of the numerical approach was based on the measured exhaust gas concentrations, optical flame positions and acoustic pressure measurements. Under overload of one design, flame fluctuations led to combustor noise and increased NOx emissions. These transient effects could not be reproduced correctly by the RANS simulations, whereby improved and more detailed methods were motivated.
Results of large eddy simulations (LES) for two geometrical variants are presented and discussed in this paper; experimental measurements of a baseload case are compared to LES and to RANS simulations with different turbulence models. Time dependent effects as the Jet In Cross-Flow fuel injection and the periodical fluctuating flame stabilization process are investigated for different operating conditions. Especially, the LES results are in good agreement with the measurement data.
- Striegan, Constantin J. D. (B&B-AGEMA GmbH)
- Struth, Benjamin (RWTH Aachen University)
- Dickhoff, Jens (B&B-AGEMA GmbH)
- Kusterer, Karsten (B&B-AGEMA GmbH)
- Funke, Harald H.-W. (Aachen Univeristy of Applied Sciences)
- Bohn, Dieter (RWTH Aachen University)
- Constantin Striegan, Development Engineer (Software)