Task 4.2: High-fidelity simulation of nonlinear dynamics of turbulent flame
This task will perform advanced numerical simulations to explore any nonlinear transitions in the flame dynamics, in particular in the run-up to thermoacoustic instability or flame flashback. Recent work at TUM (Jaensch et al 2016) has demonstrated that a hybrid CFD/state-space approach makes possible high-fidelity simulations of the self-excited instability of a laminar flame. In task 4.2 a similar approach will be applied to the turbulent swirling flame of the BRS burner, housed in Prof. Sujith's thermoacoustics laboratory at IIT Madras. We plan to exploit the fact that LES of turbulent reacting flows provides high-resolution data sets of all relevant flow quantities; the investigation of the effect of hydrogen in the fuel is then straightforward. Mode-based post-processing will be applied to this data, and the nonlinear dynamics and flow features will be related to one another. Ultimately, we will identify features that characterise the transition to instability or flashback. This should lead to the development of a monitoring system that detects impending bifurcations.