Abstract

Numerical prediction of soot production in turbulent flames is extremely challenging, as it involves complex physical and chemical processes whose modeling presents today many uncertainties. The modeling of soot growth and oxidation reactions is a key aspect for soot prediction accuracy, as it may greatly contribute to the soot mass yield as numerically observed by Rodrigues et al. [1] in a turbulent non-premixed ethylene-airflame. Surface reactions are commonly described by a HACA-based model that is known to provide good agreement with experimental data in laminar premixed flames, while failing the description of laminar diffusion flames. A modification of the HACA-RC model [2], which is an extended version of the original HACA mechanism [3], is proposed here based on the work of Hwang et al. [4] in order to obtain a soot model that performs reasonably well on both premixed and diffusion laminar flames. To assess its accurary validations are performed on different laminar flames by comparison with available experimental data. Then, the impact of such modification on the prediction of turbulent flames is evaluated by performing two Large Eddy Simulations (LES) of a model gas turbine combustor using the new model and the reference HACA-RC model. The obtained results are compared to the experimental data in terms of soot volume fraction. Discrepancies between the two LES results are finally explained by analyzing the different source terms of soot production.

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