TY - JOUR

T1 - Flamelet generated manifolds for lean premixed turbulent hydrogen flames

AU - Sanchez Bahoque, Gabriela

AU - van Oijen, Jeroen

PY - 2024/1

Y1 - 2024/1

N2 - Hydrogen is relatively simple to produce from renewable electricity, a clean energy carrier and a carbon-free alternative fuel. Therefore, the interest in developing models that can predict hydrogen combustion is continuously increasing. However, the high diffusivity of hydrogen poses a challenge, since it leads to strong wrinkling of the flame and fluctuations of elements mass fractions and enthalpy along the flame front, which are difficult to model. In this study, we investigate how the Flamelet-Generated Manifold (FGM) technique can be applied to model these phenomena. We performed Direct Numerical Simulations (DNS) of two cases with detailed chemistry and different Reynolds numbers, as a benchmark to study how well several manifolds can predict the behaviour of these flames. Then, we built several manifolds varying different parameters, such as equivalence ratio, temperature, stretch and heat release rate, both dependently and independently, in order to account for the fluctuations along the flame front caused by preferential diffusion. We found that two dimensional manifolds with equivalence ratio fluctuations are sufficient to predict the main species mass fractions, however, three-dimensional manifolds with independent variation of equivalence ratio and enthalpy, resulted in a more accurate prediction of radicals mass fractions, source terms, and turbulent burning velocity. For increasing Reynolds numbers, the discrepancies between the FGM and the DNS increase slightly. These results represent an advance in the development of a model for lean turbulent hydrogen combustion, further facilitating the execution of simulations of these types of flames in complex geometries such as gas turbines.

AB - Hydrogen is relatively simple to produce from renewable electricity, a clean energy carrier and a carbon-free alternative fuel. Therefore, the interest in developing models that can predict hydrogen combustion is continuously increasing. However, the high diffusivity of hydrogen poses a challenge, since it leads to strong wrinkling of the flame and fluctuations of elements mass fractions and enthalpy along the flame front, which are difficult to model. In this study, we investigate how the Flamelet-Generated Manifold (FGM) technique can be applied to model these phenomena. We performed Direct Numerical Simulations (DNS) of two cases with detailed chemistry and different Reynolds numbers, as a benchmark to study how well several manifolds can predict the behaviour of these flames. Then, we built several manifolds varying different parameters, such as equivalence ratio, temperature, stretch and heat release rate, both dependently and independently, in order to account for the fluctuations along the flame front caused by preferential diffusion. We found that two dimensional manifolds with equivalence ratio fluctuations are sufficient to predict the main species mass fractions, however, three-dimensional manifolds with independent variation of equivalence ratio and enthalpy, resulted in a more accurate prediction of radicals mass fractions, source terms, and turbulent burning velocity. For increasing Reynolds numbers, the discrepancies between the FGM and the DNS increase slightly. These results represent an advance in the development of a model for lean turbulent hydrogen combustion, further facilitating the execution of simulations of these types of flames in complex geometries such as gas turbines.

KW - Flamelets

KW - Hydrogen

KW - Manifolds

KW - Preferential diffusion

KW - Premixed flames

UR - http://www.scopus.com/inward/record.url?scp=85199291626&partnerID=8YFLogxK

U2 - 10.1016/j.proci.2024.105614

DO - 10.1016/j.proci.2024.105614

M3 - Article

AN - SCOPUS:85199291626

SN - 1540-7489

VL - 40

JO - Proceedings of the Combustion Institute

JF - Proceedings of the Combustion Institute

IS - 1-4

M1 - 105614

ER -