Overseas Travel Grant: Numerical Simulation and Modelling of Turbulent Premixed Flames with Detailed Chemistry

Currently, about 85\% of the world's primary energy is generated from burning coal, oil or gas; it will be decades before combustion is replaced as the main source of power generation and transport, and even longer for aircraft. The associated emissions are contributing to global climate change and to poor air quality in urban centres, and are therefore subject to increasingly stringent regulations through legislation. Alternative fuels, in particular biofuels, have the potential for net reduction in carbon emissions, but bring alternative challenges. These issues are coupled with a dependence on foreign fuel imports, exposing vulnerabilities to energy prices and security. Consequently, there is a critical need for efficient low-emission combustors for power generation and transport that are capable of burning conventional and/or alternative fuels.

This OTG proposal requests funds to visit three institutions in the US to develop four collaborations, one of which is well-established and three will be new. Two of the collaborations are based around computational software technology (Day/Bell at Lawrence Berkeley Lab, and Menon at Georgia Tech), and the other two are based around experimental datasets that can be used for comparison with numerical simulation (Driscoll at Michigan, and Lieuwen at Georgia Tech).

All four collaborations will result in an exchange of ideas, and contribute to the understanding of turbulent premixed flames that can be used for development and validation of turbulent-flame modelling approaches for applications in efficient low-emission combustion devices for power generation and transport.

The first collaboration involves a new software capability that has been designed to reduce uncertainty in models derived from experimental datasets. The idea is to use parallel computing to test models with different parameters and automatically hone in on the optimal choice. This novel approach will be applied to a engineering model that can be used to understand the chemical composition of turbulent flames to improve the prediction of emission formation.

The second collaboration involves an experimental dataset of a laboratory burner capable of investigating premixed flames exposed to extreme levels of turbulence. This will allow for direct comparison of experimental and computation data, which will be used to improve turbulent-flame models for engineering applications.

The third collaboration involves a piece of software that takes a well-established modelling approach, which is being proposed to be applied to highly-turbulent flames for comparison with the modelling approach from the first two collaborations. This second software capability can also be coupled with the software from the first collaboration, and then used to explore another particular approach to bridge the gap between length scales that are achievable through simulation with realistic length scales in experiments and industrial applications.

The fourth collaboration involves another laboratory experiment designed to recreate the conditions to explore flame instabilities that can severely damage industrial burners. Again, this collaboration will provide direct access to experimental data that can be used for comparison with numerical simulation.

The main impact of this project will be to develop collaborations between the PI, the hosts, and their associated research groups. The collaborations will lead to capability development of numerical software for the study of turbulent flames, and access to experimental data for direct comparison with numerical simulation. The resulting studies will develop fundamental understanding of turbulent combustion and enable the development and validation of engineering models that can be used to design the next generation of efficient low-emission combustors for transport and power generation. The PI and hosts will work towards publication of the resulting work in international journals and national and international conferences. The outcomes will be disseminated to the UK Consortium on Turbulent Reacting Flow and the Combustion Science and Technology SIG of the UK Fluids Network.