Control of Hydrogen and Enriched-hydrogen Reacting flows with Water injection and Intensive Strain for ultra-low Emissions

Project Information

OTHERWISE

Grant agreement ID: 101078821

DOI

10.3030/101078821

EC signature date 14 December 2022

Start date 1 May 2023

End date 30 April 2028

Funded under

• European Research Council (ERC)

Total cost

€ 1 499 958,00

EU contribution

€ 1 499 958,00

Coordinated by

TECHNISCHE UNIVERSITEIT DELFT
Netherlands

Periodic Reporting for period 1 - OTHERWISE (Control of Hydrogen and Enriched-hydrogen Reacting flows with Water injection and Intensive Strain for ultra-low Emissions)

Reporting period: 2023-05-01 to 2025-10-31

Summary of the context and overall objectives of the project

Hydrogen is expected to play a central role in the transition to clean energy, especially in sectors like aviation and power generation where electrification is not always feasible. However, burning hydrogen in turbulent conditions introduces significant challenges related to flame control, NOx emissions, and overall stability. These problems become more severe when a hydrogen flame experiences strong aerodynamic strain — a condition common in practical combustors.
The ERC-funded project OTHERWISE aims to understand and control the effects of turbulent strain on hydrogen flames. It brings together high-fidelity simulations, advanced mathematical modelling, and experimental design strategies to explore how strain can be used not only as a challenge to overcome, but also as a potential tool for enhancing flame performance and reducing emissions. The project’s ultimate goal is to provide a scientific foundation for clean, safe, and efficient hydrogen-based combustion systems.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the first two years, the OTHERWISE team developed several computational tools to investigate hydrogen combustion under strain. These include:

- Advanced simulations (DNS) of turbulent hydrogen flames, with new techniques to handle complex boundary conditions and flow instabilities.
- A novel modelling approach using probability density functions (PDFs) and flamelet-based methods, which allow accurate predictions of pollutant formation and flame behaviour under strain.
- Integration of effects like water injection and preferential diffusion, which are important in practical combustion environments when hydrogen is used as fuel.

The most remarkable scientific achievement obtained so far is the strain-induced suppression of NOx emissions. Further scientific achievements include the discovery of:

- Bimodal behaviour in the distribution of key flame parameters under strong strain, and
- A previously unobserved inversion of flame response to acoustic forcing at high strain levels.

In parallel, the team is developing low-order tools to help identify combustor geometries that naturally generate controlled flame strain — a crucial step toward practical application.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The project has advanced the scientific understanding of how hydrogen flames behave under extreme conditions, especially where standard models and assumptions no longer hold. For example, the combination of preferential diffusion and aerodynamic strain has been shown to affect pollutant formation and flame stability in ways that were not previously captured by existing simulation tools.

These results pave the way for improved combustion models that are both physically accurate and computationally efficient. This is essential for designing next-generation engines and combustors that rely on hydrogen as a primary fuel. Looking forward, the outcomes of OTHERWISE may support:

- Cleaner hydrogen engines for aviation and power generation,
- Better predictive tools for industry design,
- New safety strategies for controlling flame behaviour in challenging conditions.

By tackling these issues at a fundamental level, the project contributes to the broader European goals of climate neutrality, technological leadership, and energy resilience.

High-fidelity simulation of a hydrogen flame under highly strained and turbulent conditions.