Session: 04-17 Combustion Modeling V

Paper Number: 128717

128717 - Modeling and Predicting Deflagration Phenomena in Hydrogen-Enriched Gas Turbine Exhausts: A CFD Approach 

The adoption of hydrogen-enriched fuels in gas turbine power plants is gaining prominence as an effective strategy for decarbonization. However, this transition presents unique challenges, particularly in relation to hydrogen's wider flammability range compared to natural gas when mixed with air. Under certain operating conditions, this can lead to the undesired formation of flammable mixtures within the gas turbine exhaust channel, which, if ignited, can result in structural damage due to pressure increases caused by the deflagration process. An effective and robust way of assessing the related safety risk is to rely on reliable high-fidelity Computational Fluid Dynamics (CFD) models, capable of accurately predicting the overpressure generated by the ignition of flammable mixtures.

In this study, a CFD model has been developed to perform three-dimensional and unsteady simulations of the deflagration of hydrogen-air mixtures within large partially confined volumes, representative of industrial gas turbine exhausts. A high-fidelity Large Eddy Simulation (LES) approach coupled with the Renormalization Group Theory (RNG) subgrid model was employed for turbulence modeling, while the Flamelet Generated Manifold (FGM) tabulated chemistry approach with the Turbulent Flame Speed Closure (TSFC) was adopted as the combustion model. Computational results have then been compared to experimental data from the literature to validate the presented model in terms of numerical domain discretization, turbulence modeling, and combustion modeling. The analysis is aimed at replicating the main overpressure peaks as measured by the British Gas Midlands Research Station. While exhibiting a satisfactory alignment with the test case experimental pressure distribution, the proposed setup was able to capture the main dynamics of the deflagration process, revealing to be ready for application to real gas turbine exhaust geometries.

The setup has been then used to simulate the deflagration process of a hydrogen-air mixture at the exhaust of an industrial gas turbine exhaust manufactured by Baker Hughes. A discussion on this latter case has been reported as well in this paper.

Presenting Author: Gianmarco Lemmi University of Florence, Department of Industrial Engineering (DIEF)

Presenting Author Biography: Gianmarco Lemmi is a 2nd year Ph.D. student at the Department of Industrial Engineering of the University of Florence and a member of the Heat Transfer and Combustion group. He embarked on his academic journey in Mechanical Engineering - Aeronautical Propulsion, earning his Master's degree in 2021 with a thesis based on the use of a specific dynamic mesh approach for flapping airfoils application. In his current role as a Ph.D. student, Gianmarco has honed his expertise in computational fluid dynamics (CFD), specializing in the modeling of reactive flow phenomena, particularly in the analysis of gas turbine combustors. His research takes center stage in exploring the enhancement of the Flamelet Generated Manifold combustion model, with a focus on accommodating preferential diffusion for Hydrogen and its applicability in dual-fuel systems.

Authors:

Gianmarco Lemmi University of Florence, Department of Industrial Engineering (DIEF)
Pier Carlo Nassini Baker Hughes
Matteo Cerutti Baker Hughes
Antonio Andreini University of Florence, Department of Industrial Engineering (DIEF)