Abstract
In this work, the performances of two recently developed finite-rate dynamic scale similarity (SS) sub-grid scale (SGS) combustion models (named DB and DC) for non-premixed turbulent combustion are a priori assessed based on three Direct Numerical Simulation (DNS) databases. These numerical experiments feature temporally evolving syngas jet flames with different Reynolds (Re) numbers (2510, 4487 and 9079), experiencing a high level of local extinction. For comparison purposes, the predicting capability of these models is compared with three classical non-dynamic SS models, namely the scale similarity resolved reaction rate model (SSRRRM or A), the scale similarity filtered reaction rate model (SSFRRM or B), and a SS model derived by the “test filtering” approach (C), as well as an existing dynamic version of SSRRRM (DA). Improvements in the prediction of heat release rates using a new dynamic model DC are observed in high Re flame case. By decreasing Re, dynamic procedures produce results roughly similar to their non-dynamic counterparts. In the lowest Re, the dynamic methods lead to higher errors.
Highlights
In the governing equations of Large Eddy Simulation (LES) of reactive flows with detailed kinetics, transport equations of the filtered species mass fractions are solved
– developing dynamic versions of finite-rate Scale Similarity (SS) Sub-grid scale (SGS) models B and C, – assessing their prediction capability by using 3 Direct Numerical Simulation (DNS) databases of complex 3D temporal non-premixed jets in which the flames experience a high level of local extinction
In [21], the turbulent kinetic energy (TKE) spectrum of the H case DNS was constructed at the mid plane of the jet at the same time instant used in this study
Summary
In the governing equations of Large Eddy Simulation (LES) of reactive flows with detailed kinetics, transport equations of the filtered species mass fractions are solved. The EDC and PaSR, which have been developed for Reynolds Average Naiver Stokes (RANS), are being extended to LES In their general form (i.e., Bardina’s approach [15] for the closure of the SGS stress field), Scale Similarity models are soft deconvolution methods [16, 17], which use low order approximations to reconstruct the exact field based on filtered fields. – developing dynamic versions of finite-rate SS SGS models B and C, – assessing their prediction capability by using 3 DNS databases of complex 3D temporal non-premixed jets in which the flames experience a high level of local extinction. Three classical non-dynamic finite-rate SS SGS combustion models are selected: the two proposed in [13] (i.e. SSRRRM and SSFRRM) and the one developed based on Germano’s test filtering approach [20, 21].
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