Numerical Simulation of a Reacting Jet in a Vitiated Cross Flow Using a Novel Progress Variable Approach
Staged/sequential combustion is a state of the art method to provide operational flexibility and reduced emissions in gas turbines. To use Computational Fluid Dynamics (CFD) to study such systems a reliable and computationally inexpensive turbulent combustion model is necessary. A key requisite for such a model is the accurate determination of the flame location in order to predict emissions, flame dynamics, and temperature distribution. Previously a model was developed for reheat combustion, based on a progress-variable method using auto-ignition reactors. However, sequential combustion systems are now being implemented where both auto-ignition and flame propagation are important. Consequently, the reheat model has been extended to consider flame propagation in mixtures that do not auto-ignite. This has been achieved by incorporating a small proportion of combustion products in the reactant mixture considered by the reactor. This approach has broadened the model’s applicability to address the full space between auto-ignition and flame propagation regimes. The revised model has been validated by comparison with reacting jet in vitiated cross-flow experiments demonstrating a significantly better prediction of the position of both attached and lifted flames than the original model.