Session: 04-15 Combustion Modeling III

Paper Number: 128966

128966 - Numerical Investigation of Reheat Hydrogen Flames in the Sequential-Combustion Stage of a Heavy-Duty Gas Turbine 

Recent theoretical studies and experimental evidence suggest that turbulent burning-rate augmentation, flame instabilities and NOx emissions, notoriously characterizing fuel-lean hydrogen premixed combustion, are significantly mitigated at reheat combustion conditions. This is due to the favorable effects of high reactants temperature in reducing the strength of thermo-diffusive instabilities that occur in hydrogen premixed combustion with augmented severity for increasing pressure and flame temperature. In this context, Ansaldo’s Constant Pressure Sequential Combustion (CPSC) system appears as an attractive approach to enable hydrogen firing of gas turbines that target high flame temperatures to retain high cycle efficiency. The present numerical modelling effort represents the first attempt to perform high-resolution Large-Eddy Simulation (LES), featuring detailed chemical kinetics and a fully compressible representation of the reactive flow, of hydrogen reheat combustion in a full-scale industrial combustor geometry with realistic geometrical features. Building upon earlier numerical modelling efforts that were limited to generic and geometrically simplified configurations with idealized reactants mixing conditions (GT2022-83218), the ability of the turbulent combustion model to predict injection of the hydrogen fuel, mixing with the vitiated oxidant stream and spontaneous ignition of the reactants mixture at the expected stabilization location is verified. Part- and full-load conditions for 100% hydrogen-firing of the engine are simulated confirming that the numerical results are in accordance with the expected flame stabilization behavior observed in test-rig experiments. Furthermore, an analysis of the hydrogen premixed flame structure at reheat combustion conditions is provided highlighting the differences observed at various locations within the combustion chamber.

Presenting Author: Andrea Gruber SINTEF Energy Research

Presenting Author Biography: Andrea Gruber holds a doctoral degree in Mechanical Engineering from NTNU (2006), he is Senior Research Scientist at SINTEF Energy Research and Adjunct Professor at NTNU. His research interests are in the development and application of massively parallel direct numerical simulations (DNS), a high-fidelity numerical approach to accurately predict turbulent reactive flows. Over a period of nearly two decades and in a close and fruitful collaboration with combustion researchers from Sandia Lab (Livermore, CA), Dr. Gruber has initiated the deployment of DNS on some of the research challenges related to combustion of highly reactive and non-standard fuels in gas turbines (hydrogen in particular). Pursuing industrial relevance within the framework of numerous national and European initiatives (BIGH2, NCCS, DiHI-Tech, ENCAP, DECARBit, FLEX4H2, HyPowerGT) and in close partnership with the gas turbine industry (ALSTOM, Ansaldo Energia, Siemens Energy, Thomassen Energy), he has contributed to the fundamental understanding of key turbulence-chemistry interaction processes that play a major role in the achievement of clean and efficient power generation: design and optimization of fuel injection systems, flashback prediction and control, static and dynamic flame stabilization in conventional and staged combustors.

Authors:

Andrea Gruber SINTEF Energy Research
Ole Meyer SINTEF Energy Research
Tarjei Heggset SINTEF Energy Research
Birute Wood Ansaldo Energia Switzerland
Andrea Ciani Ansaldo Energia Switzerland