A Priori Validation of a Multidimensional Turbulent Premixed Combustion Model for High-Pressure Bunsen Flames

Abstract

ABSTRACT Recently, the authors proposed a model for the filtered reaction source term conditioned on Favre filtered progress variable in turbulent premixed flames based on filtering of one-dimensional laminar flame profiles. Multidimensional effects from flame propagation at oblique angles through LES filter volumes and from subgrid flame folding were considered by a Gaussian filter kernel and through a wrinkling factor, respectively. Using a DNS database (one-step Arrhenius chemistry, unity Lewis number and constant transport) of statistically flat turbulent flames at different turbulence intensities and at ambient pressure, the model had been validated a priori and some model constants were adapted. Here, the model is validated for a Bunsen flames at varying inlet velocity, turbulence level, turbulent length scale and at higher pressure. In the Bunsen flames at bar, regions of strong curvature reminiscent of Landau-Darrieus instability appear, causing a faster increase of the wrinkling factor at small filter sizes than for the lower pressure flames. The effect is captured by a simple extension of the wrinkling factor model. Very good agreement between model and DNS filtered source term distributions is achieved using this adapted combustion model.