Development of Adaptive Closure Models for Large Eddy Simulations of Lean Blow-Out Conditions

The objective of the proposed Phase II effort is to establish fundamental understanding of combustion-physical mechanisms leading to blowout, the critical evaluation of model limitations in predicting these blowout processes and the development of an improved combustion model to enable the prediction of lean blowout (LBO) in swirl-stabilized combustors. For this, high-resolution numerical simulations of an experimental laboratory-scale swirl combustor will be performed at transient blowout conditions. Different operating regimes will be considered to establish a comprehensive understanding of relevant blowout mechanisms for premixed, partially premixed, and diffusion flame regimes. By considering an experimental swirl-combustor configuration, existing measurements will allow for assessment of the predictive capabilities. High-resolution transient LBO simulations will complement the existing measurements and form a basis for combustion model analysis. To effectively interrogate these transient and multidimensional results, data analysis tools will be developed. These tools will be employed for analyzing the transient approach to blowout with specific emphasis on describing the spatial and temporal evolution of blowout phenomena. The present effort aims at pursuing the development of the strategy initiated in Phase I for predicting the onset of blowout with numerical simulations.