Development of predictive modelling tools of combustion instability for gas turbines

Combustion-based energy technology has been underpinning modern industrial development and is expected to do so for the foreseeable future. It may sound old-fashioned to advocate combustion-based technology, but it is the current status and there are strong reasons for it. Although there is rapid growth of renewable technologies such as wind, tide, solar, etc, however, those renewable energies still suffer from reliability, flexibility, and cost-effectiveness.

Although more reliable and stable, modern gas turbines recently faces a problem of combustion instability. The combustion instability is defined as an unstable combustion arising from a coupling between pressure and heat release. In an enclosed combustion chamber, small disturbances are trapped, and grow to larger pressure/temperature fluctuations due to a coupling. Although the fundamental nature of combustion instability was identified 100 years ago by Rayleigh, the detailed coupling mechanisms in practical systems are not fully understood. Complex combustor geometries and its multi-physics nature have been hindering a clear understanding of combustion instability mechanisms.

The proposed PhD project is aimed to develop a robust, reduced-order modelling to capture the onset of combustion instability for gas turbines and similar combustion systems. The student would conduct high fidelity simulation of oscillating flames and performed careful analysis to investigate:
- Identification of the relationship between the flame curvature and the turbulent flame speed;
- Quantification of turbulent Markstein lengths at given flow conditions;
- Identification of individual contributing terms on the turbulent Markstein length;
- Comparisons of simulated turbulent Markstein length with the derivations from reduced order modelling and experimental measurements.

This project will be conducted in collaboration with Georgia Institute of Technology, USA and Newcastle University.