LES and Multi-Step Chemical Reaction in Compartment Fires

Yuen, Anthony; Yeoh, Guan Heng; Timchenko, Victoria; Barber, Tracie

doi:10.1080/10407782.2015.1012886

Cited by 24 publications

(11 citation statements)

References 49 publications

(71 reference statements)

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“…It applies the large eddy simulation (LES) methodology and can simulate the temporal heat and mass transport, as well as gas species and smoke movement of fire plumes for low-speed flows [23]. In LES, the instantaneous fluctuation behaviours due to the turbulent mixing can be considered and fully-coupled with the combustion, soot, and radiation models [24,25]. The combustion model used in the current simulations is a mixing-controlled fast chemistry model based on the "mixed is burnt" assumption, in which the eddy dissipation concept [26,27] is applied for evaluation of the time-averaged chemical source term.…”

Section: Methodsmentioning

confidence: 99%

Fire Risk Assessment of Combustible Exterior Cladding Using a Collective Numerical Database

Chen

Yuen

Yeoh

et al. 2019

Fire

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Recent high-profile building fires involving highly-combustible external cladding panels in Australia as well as Dubai, China, and the United Kingdom have created a heightened awareness by the public, government, and commercial entities to act on the risks associated with non-compliant building structures. In this paper, a database of fire events involving combustible aluminium composite panels was developed based on (i) review of relevant major fire events in Australia and other countries, and (ii) numerical simulation of the ignitability, fire spread, and toxic emissions associated with composite panels. Through the application of large-eddy-simulation (LES)-based computational fire field models, the associated risks for a standardized two-storey building with external cladding was considered in this study. A total of sixteen simulation cases with different initial sizes of the fire and different air cavity widths in the exterior cladding assembly were examined to investigate the tolerable situations and their influences. It was discovered that for most cases, with an initial fire size greater than 400 kW/m−2, the fire will spread from the first to second floor before the allowed egress time period.

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Section: Methodsmentioning

confidence: 99%

Fire Risk Assessment of Combustible Exterior Cladding Using a Collective Numerical Database

Chen

Yuen

Yeoh

et al. 2019

Fire

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“…In essence, the mixture fraction governs the amount of the fuel mixture in each control volume element in the simulation domain. The scalar dissipation is a term that is introduced to describe the strain and extinction of the flame, in which the magnitude of this quantity depicts the departure of the combustion process away from its chemical equilibrium [31]. It should be noted that, in the present work, the GRI-MECH 3.0 detailed chemical reaction mechanisms, which includes 325 reaction steps and 53 chemical species [32], was implemented to formulate the flamelet library for the strained laminar flamelet model, with ethylene (C 2 H 4 ) being selected as the parental fuel.…”

Section: Turbulence and Combustion Modellingmentioning

confidence: 99%

Sensitivity Analysis of Key Parameters for Population Balance Based Soot Model for Low-Speed Diffusion Flames

et al. 2019

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In this article, the evolution of in-flame soot species in a slow speed, buoyancy-driven diffusion flame is thoroughly studied with the implementation of the population balance approach in association with computational fluid dynamics (CFD) techniques. This model incorporates interactive fire phenomena, including combustion, radiation, turbulent mixing, and all key chemical and physical formation and destruction processes, such as particle inception, surface growth, oxidation, and aggregation. The in-house length-based Direct Quadrature Method of Moments (DQMOM) soot model is fully coupled with all essential fire sub-modelling components and it is specifically constructed for low-speed flames. Additionally, to better describe the combustion process of the parental fuel, ethylene, the strained laminar flamelet model, which considers detailed chemical reaction mechanisms, is adopted. Numerical simulation is validated against a self-conducted co-flow slot burner experimental measurement. A comprehensive assessment of the effect of adopting different nucleation laws, oxidation laws, and various fractal dimension and diffusivity values is performed. The results suggest the model employing Moss law of nucleation, modified NSC law of oxidation, and adopting a fractal dimension value of 2.0 and Schmidt number of 0.9 yields the simulation result that best agreed with experimental data.

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“…Essentially, the mixture fraction governs the proportion of the fuel mixture in each control volume element in the discretised domain, and the first two moments of the mixture fraction, namely the mean mixture fraction, f , and the mixture fraction variance, g, are evaluated by resolving their conservation equations, respectively. Scalar dissipation is introduced to describe the strain and extinction of the flame, in which larger values of this quantity depict its departure from chemical equilibrium [49]. The scalar dissipation across the flamelet is determined based on the mean scalar dissipation of the flamelets embedded in turbulent flames at the position where f = f st , as well as the ratio of the function of the mixture fraction and density at the point of interest and at the position where f is stoichiometric.…”

Section: Numerical Detailsmentioning

confidence: 99%

Influence of Eddy-Generation Mechanism on the Characteristic of On-Source Fire Whirl

et al. 2019

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This paper numerically examines the characterisation of fire whirl formulated under various entrainment conditions in an enclosed configuration. The numerical framework, integrating large eddy simulation and detailed chemistry, is constructed to assess the whirling flame behaviours. The proposed model constraints the convoluted coupling effects, e.g., the interrelation between combustion, flow dynamics and radiative feedback, thus focuses on assessing the impact on flame structure and flow behaviour solely attribute to the eddy-generation mechanisms. The baseline model is validated well against the experimental data. The data of the comparison case, with the introduction of additional flow channelling slit, is subsequently generated for comparison. The result suggests that, with the intensified circulation, the generated fire whirl increased by 9.42 % in peak flame temperature, 84.38 % in visible flame height, 6.81 % in axial velocity, and 46.14 % in velocity dominant region. The fire whirl core radius of the comparison case was well constrained within all monitored heights, whereas that of the baseline tended to disperse at 0.5 m height-above-burner. This study demonstrates that amplified eddy generation via the additional flow channelling slit enhances the mixing of all reactant species and intensifies the combustion process, resulting in an elongated and converging whirling core of the reacting flow.

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LES and Multi-Step Chemical Reaction in Compartment Fires

Cited by 24 publications

References 49 publications

Fire Risk Assessment of Combustible Exterior Cladding Using a Collective Numerical Database

Fire Risk Assessment of Combustible Exterior Cladding Using a Collective Numerical Database

Sensitivity Analysis of Key Parameters for Population Balance Based Soot Model for Low-Speed Diffusion Flames

Influence of Eddy-Generation Mechanism on the Characteristic of On-Source Fire Whirl

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