The increased demand and limited supply of fossil fuels drives the search for alternative fuels for all modes of transportation and electrical power generation.
Also, we are witness to an increasing awareness of environmental issues and the human impact. In particular, air transport’s contribution to climate change represents 2% of human-created CO2 emissions. This is motivating active policies to make air transport greener and more sustainable: The International Air Transport Association (IATA) and the European Union have set targets for the reduction of 50% CO2 and 80% NOx emissions in 2050.
Hydrogen is a promising candidate for replacing fossil fuels in aviation. If produced from a regenerative source it is a carbon-free (green hydrogen). The direct emissions are free of carbon oxides and other contaminants; the only emissions are water vapour and oxides of nitrogen (NOx). Still, hydrogen combustion is promising in further reducing the NOx emission compared to conventional fuels. In addition, hydrogen’s high specific energy makes it an ideal candidate for aviation.
The use of hydrogen in combustors of gas turbines presents a number of technological challenges. The high reactivity of hydrogen may lead to flame auto-ignition, flashback, and other thermo-diffusive instabilities. Hence, novel fuel injection/mixing solutions are key towards the viability of burning hydrogen in gas turbines, making the most of the opportunities it provides (additional to the decarbonization): shorter combustion (smaller – cheaper- combustion chamber) and flatter traverse/cycle efficiency.
Combustion chambers need to be redesigned to meet the simultaneous requirements of hydrogen use (for GHG reduction/suppression), high combustion efficiency and flame stability, and with minimal nitric oxide emissions
The particular three objectives of the first subproject, developed at CMT-UPV, are:
Development and construction of novel test bench for hydrogen combustion studies.
Flow and flame characerization under relevant gas turbine operating conditions.
Creation of an experimental database for model validation.
In line with these, the specific objectives of the second subproject, developed at Numath-UPM, are:
Development of new high-fidelity models and simulation strategy.
Identification of mechanisms of instabilities during hydrogen combustion.
Identification of instabilities suppression/reduction parameters and stratgies.
SHYGAS pursues a deeper knowledge on the physical mechanisms leading to flashback, other thermoacoustic interactions and on the manner in which a premixed lean-hydrogen swirling combustor can be optimised to (i) increase the resistance to flashback and (ii) reduce the NOx emissions at safe continuous operation conditions.
A coordinated research plan is proposed, in which the research group at UPV will focus on the experimental part, and the group at UPM on the computational part. This sub-project SHYGAS corresponds to the computational and is divided in three main workpackages.
High fidelity (LES) numerical simulations will be carried out using an in-house Spectral Element Multiphysics solver that will be upgraded as part of the project to account for the hydrogen combustion under continuous operation conditions.
Data-driven analysis techniques (POD, SPOD and DMD) will be applied to the experimental data obtained by UPV and to the high fidelity simulations, to gain physical insight and produce reduced-order models of the relevant physical mechanisms.
Stability and receptivity analyses of the flow in the combustor will deliver predictive models of the physical mechanisms driving the formation of flow patterns like vortex core precession or thermo-acoustic instabilities, that have a dramatic impact on the combustor dynamics and performance. A coordinated research plan is proposed, in which the research group at UPM focuses on the computational part, and the group at UPV on the experimental part.
