Wind and Fire Coupled Modelling—Part II: Good Practice Guidelines

Węgrzyński, Wojciech; Lipecki, Tomasz; Krajewski, Grzegorz

doi:10.1007/s10694-018-0749-4

Cited by 18 publications

(11 citation statements)

References 148 publications

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“…As there are no guidelines for this particular use of numerical modelling, we recommend following the recommendations of OECD [26]. Some useful considerations on CFD modelling in fire safety engineering may be also found in [47].…”

Section: The Results For Mixtures With a Small Value Of ∆ρmentioning

confidence: 99%

Numerical Modelling of the Fire Extinguishing Gas Retention in Small Compartments

Boroń¹,

Węgrzyński²,

Kubica³

et al. 2019

Applied Sciences

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Active fire protection systems are critical elements of good process safety. Among them, gaseous extinguishing systems provide quick, clean suppression and prolonged protection due to long retention process of the gas. Standard design methods do not provide sufficient tools for optimisation of the retention process, thus the necessity for development and validation of new tools and methods—such as Computational Fluid Dynamics (CFD) simulations. This paper presents a simplified approach to CFD modelling, by the omission of the discharge phase of the gas system. As the flow field after discharge is stable and driven mainly by the hydrostatic pressure difference, buoyancy and diffusion, this simplified approach appears as an efficient and cost-effective approach. This hypothesis was tested through performing CFD simulations, and their comparison against experimental measurements in a bench scale in a small compartment (0.72 m3), for six mixtures that differ in their density. Modelling the retention of the standard IG55 mixture was very close to the experiment. Modelling of mixtures with a density close to the density of ambient air has proven to be a challenge. However, the obtained results had sufficient accuracy (in most cases relative error <10%). This study shows the viability of the simplified approach in modelling the retention process, and indicates additional benefits of the numerical analyses in the determination of the fire safety of protected premises.

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Section: The Results For Mixtures With a Small Value Of ∆ρmentioning

confidence: 99%

Numerical Modelling of the Fire Extinguishing Gas Retention in Small Compartments

Boroń¹,

Węgrzyński²,

Kubica³

et al. 2019

Applied Sciences

Self Cite

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“…The comparisons detailed in this analysis show the potential for the presented model to estimate multi-modal wind direction distributions representing complicated wind behaviours, which include re-circulation regions on leeward slopes. The expression of the wind as a boundary condition in modelling is an accomplishment of the meso-scale atmospheric phenomena via an Atmospheric Boundary Layer simulation in CFD [33]. This implementation typically needs to have three terms specified, including a vertical profile for average speed, the turbulence features and the upstream aerodynamic roughness length.…”

Section: Fire Modelling and Wind Interactionmentioning

confidence: 99%

Existing Improvements in Simulation of Fire–Wind Interaction and Its Effects on Structures

Ghodrat

Shakeriaski

Nelson

et al. 2021

Fire

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This work provides a detailed overview of existing investigations into the fire–wind interaction phenomena. Specifically, it considers: the fanning effect of wind, wind direction and slope angle, and the impact of wind on fire modelling, and the relevant analysis (numerical and experimental) techniques are evaluated. Recently, the impact of fire on buildings has been widely analysed. Most studies paid attention to fire damage evaluation of structures as well as structure fire safety engineering, while the disturbance interactions that influence structures have been neglected in prior studies and must be analysed in greater detail. In this review article, evidence regarding the fire–wind interaction is discussed. The effect of a fire transitioning from a wildfire to a wildland–urban interface (WUI) is also investigated, with a focus on the impact of the resulting fire–wind phenomenon on high- and low-rise buildings.

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“…A sample view of the numerical mesh in the vicinity of the ventilator (the area where sprinkler activation time was assessed) is shown in Figure 2. The mesh was created following the guidelines presented in [37] and was verified following a mesh sensitivity analysis. For this purpose, one case (fire scenario 2, closed vent) was simulated on three different models.…”

Section: Case Study-numerical Modelmentioning

confidence: 99%

“…On the other hand, increasing the mesh size to δx = 0.2 m resulted in significant differences in activation time for almost all of the scenarios. In consequence, the medium (δx = 0.1 m) mesh was chosen for the rest of The mesh was created following the guidelines presented in [37] and was verified following a mesh sensitivity analysis. For this purpose, one case (fire scenario 2, closed vent) was simulated on three different models.…”

Section: Case Study-numerical Modelmentioning

confidence: 99%

3D Mapping of the Sprinkler Activation Time

et al. 2020

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Sprinkler activation is one of the key events defining the course of a compartment fire. The time when activation occurs is commonly used in the determination of the design fire scenario, which is the cornerstone of the design of building fire safety features. A well-known model of sprinkler activation (response time index (RTI) model) was introduced into the numerical scheme of the ANSYS Fluent computational fluid dynamics (CFD) package. The novel way in which the model is used is the calculation of the time for sprinkler activation within each discrete cell of the domain. The proposed novel approach was used in a case-study to assess the effects of comfort mode natural ventilation on a sprinkler’s activation pattern. It was found that hinged vents in the comfort mode had a significant effect on sprinkler activation, both in terms of delaying it as well as limiting the total number of cells in which the sprinkler would have activated. In some scenarios with a hinged vent, no activation was observed in the central point of the vent, possibly indicating problems with the autonomous triggering of the fire mode of such a device. It was also found that the RTI and C (related to the conductive transport of sprinkler fitting) parameter values had a moderate influence on sprinkler activation time—only for high-temperature sprinklers (≥ 141 °C). This study shows the applicability of the 3D activation time mapping for research focused on the fire safety of sprinkler-protected compartments and for the performance-based approach to sprinkler system design. Even though the RTI model is the industry standard for the determination of sprinkler response, the model implementation in ANSYS Fluent was not validated. This means that sources of uncertainty, mainly connected with the determination of flow velocity and temperature are not known, and the model should be used with caution. An in-depth validation is planned for subsequent studies.

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Wind and Fire Coupled Modelling—Part II: Good Practice Guidelines

Cited by 18 publications

References 148 publications

Numerical Modelling of the Fire Extinguishing Gas Retention in Small Compartments

Numerical Modelling of the Fire Extinguishing Gas Retention in Small Compartments

Existing Improvements in Simulation of Fire–Wind Interaction and Its Effects on Structures

3D Mapping of the Sprinkler Activation Time

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