Influence of gas radiative property models on Large Eddy Simulation of 1 m methanol pool fires

Abstract

The main objective of this work is to analyze the effects of gas radiative property models on the radiative outputs and flame structure in a 1 m diameter methanol pool fire. Large Eddy Simulation (LES) are run with the non-adiabatic steady laminar flamelet (SLF)/presumed filtered density function (FDF) model to close subgrid-scale (SGS) turbulence-chemistry and turbulence-radiation emission interactions. The radiative transfer equation (RTE) is solved using the Finite Volume Method (FVM) with different angular meshes, including uniform angular dicretizations comprising 16 (polar angle) × 24 (azimuthal angle) and 48 × 96 control angles and the FT n scheme with n up to 48. Four gas radiative property models, namely the Rank Correlated Full Spectrum k-distribution (RCFSK), the non-grey Weighted-Sum-of-Grey-Gases (WSGG), and two versions of the grey WSGG based on different evaluations of the mean path length are assessed. Model predictions with the RCFSK reproduce with fidelity the available experimental data in terms of

Modelling and effects of fuel radiation in methanol pool fires

“…These pool fires are also target flames in the MacFP workshop [22]. We performed LES of these flames in previous studies with the numerical model described in Section 3 by disregarding methanol radiation [11,12]. These simulations were performed with Code_Saturne developed at EDF [23].…”

“…A detailed description of the model was reported in the previous articles [11,12]. The numerical model solves the filtered transport equations of mass, momentum, enthalpy, mixture fraction and second moment of mixture fraction.…”

“…The computational domains and grids for both the 30 cm and 1 m methanol pools are the same as in Refs. [11,12] and are summarized in Table 1. For all the simulations, the computational domain is bounded by open boundaries at the top and sides and typical convective and outflow/inflow conditions are applied, respectively.…”

“…On the other hand, global non-grey models based on the k-distribution concept, such as the Full-Spectrum Correlated-k (FSCK) or the Spectral Line based Weighted-Sum-of-Grey-Gases (SLW) [10], combine accuracy and computational efficiency and are good candidate to be applied in LES of fire scenarios (see Refs. [11][12][13] for example). These models lie on the assumption of correlated spectrum to deal with non-homogeneous non-isothermal medium.…”

Large eddy simulation of fire-induced flows using Lattice-Boltzmann methods

“…LES of non-sooting and sooting fire plumes were reported in the literature with different levels of sophistication in the modeling of subrid-scale turbulence [4][5][6][7][8][9][10][11][12][13][14], turbulent combustion [14][15][16], radiative heat transfer [17][18][19], and soot modeling [16,20,21]. One of the difficulty in the modeling of the near field of fire plumes is that the flow, and the resulting air entrainment that controls the combustion process, is governed by the formation and growth of the flame base non-dissipative laminar instability near the edge of the pool that develops periodically to form energy containing large-scale toroidal vortices [22,23].…”