Motivation
Global climate change is perceived as a dangerous threat for our planet, with important consequences for the energy sector. Combustion of hydrogen from renewable energies is an emerging alternative technology that can replace fossil fuels and so provide carbon-neutral energy.
The objective of the Innovative Training Network POLKA (Pollution Know-how and Abatement) is to solve serious technical problems, which are specific to hydrogen combustion: thermoacoustic instabilities and flashback. Thermoacoustic instabilities are large-amplitude pressure oscillations produced by interactions between the flame and acoustic waves. They tend to occur unexpectedly and can cause catastrophic damage to hardware combustor. Flashback is the dangerous phenomenon of the flame propagating backwards into components not designed for high temperatures.
Objectives and Strategy
The research project is divided into interconnected work packages, each containing sub-projects focused on specific research tasks. Selected ESRs of TFD group focus on:
Scaling laws for the effect of hydrogen content on flame dynamics and on thermoacoustic frequencies: the goal here is to develop scaling rules that describe the effect of hydrogen content on the flame transfer function (FTF) and important characteristics of thermoacoustic oscillations: stability, frequency, amplitude. A first phase consists on the identification of physical mechanisms of flow-flame interaction using highly resolved combustion simulations, the study could lead to attribute physical representation to the commonly used parameters representing the FTF as a ‘grey-box’. In the second phase, the combination of the mechanisms will be considered and scaling rules are established to relate the FTF and thermoacoustic frequencies and stability analysis to hydrogen content.
High-fidelity simulation of nonlinear dynamics of turbulent flame: the task will focus on exploring any nonlinear transitions in the flame dynamics, in particular preceding a thermoacoustic instability or flame flashback. In order to investigate the effect of hydrogen in the fuel, an LES of turbulent reacting flows will be performed providing high-resolution data sets of all relevant flow quantities. Mode-based analysis will be applied and the nonlinear dynamics and flow features will be examined. Ultimately, the task will aim to identify precursors of instabilities or flashback and hence develop a monitoring system detecting impending bifurcations.
Dynamics of hydrogen flames and retro-fitting engines: work on this task will be carried out in Siemens Industry Software, Leuven and co-supervised by Prof. Dr. Polifke. The goal here is to create a high-fidelity simulation environment in STAR-CCM+ able to represent and reproduce hydrogen enriched flame dynamics from the laboratory test rig by Garcia-Armingol & Ballester 92015. After the validation of the numerical simulations with the experimental data, the set software platform will be used to determine FTFs for various hydrogen concentrations (which are also needed in other tasks of the POLKA network) and to perform susceptibility analysis to flashback.
Acknowlegment
This project is funded by the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement No 813367