Empirical correlation derived by CFD simulation on heat source location and ventilation flow rate in a fire room

Tlili, Ons; Mhiri, Hatem; Bournot, Philippe

doi:10.1016/j.enbuild.2016.04.028

Cited by 19 publications

(6 citation statements)

References 19 publications

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“…Another important conclusion is the need of carefully choosing of the turbulence model to be used. The k-ε and k-ω turbulence models, which are commonly regarded as industry standards [40][41][42][43][44], may fail when used for fire modeling in a confined space. This is due to expected anisotropy of flows, high velocity gradients and the essential role of buoyancy forces.…”

Section: Discussionmentioning

confidence: 99%

A Study on the Reliability of Modeling of Thermocouple Response and Sprinkler Activation during Compartment Fires

et al. 2022

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Real and numerical fire experiments involve temperature measurements with thermocouples, and thus some considerations on numerical modeling of this process are presented and a new approach to thermocouple modeling is introduced. Using ANSYS Fluent software a well-recognized analytical thermocouple model was implemented in each cell of the computational domain, which allows for determination of thermocouple responses as a continuous field. Similarly, sprinklers are key elements of fire-protection systems. Sprinklers activation is one of the breakthrough moments during the course of a compartment fire. Therefore, assumptions on sprinkler activation time are of crucial importance when designing a fire safety system. Just as for thermocouple modeling, virtual sprinklers based on a commonly admitted response time index (RTI) model were placed in all cells. The proposed approach provides data on sprinklers activation or thermocouple response for the whole domain instead of retrieving data point by point only for predefined locations. In this study, experimental data available in the literature were used for the validation of the proposed approach. In addition, the results were compared with those obtained with the commonly used Fire Dynamic Simulator (FDS) software. The outcomes might be of a significant importance for practitioners, who deal with fire experiments and fire protection. Furthermore, some issues on accurate modeling of fire gases flow are discussed extensively. It was found that commonly applied k-ε and k-ω turbulence models might fail in the case of modeling of fire plumes in confined spaces.

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Section: Discussionmentioning

confidence: 99%

A Study on the Reliability of Modeling of Thermocouple Response and Sprinkler Activation during Compartment Fires

et al. 2022

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“…This solver has been widely used in fire research analyses and is recognized by some of the smoke control standards [26]. Some validation examples for ANSYS Fluent were given in [27][28][29][30][31]. The principal assumptions for numerical calculations and the choice of physical sub-models are summarized in Table 1.…”

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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“…Furthermore, ANSYS allows for almost unconstrained creation of complex geometry with unstructured meshes (tetrahedral, polyhedral) and efficient parallelization of the solution. Validation cases exist for ANSYS Ò Fluent Ò software in fire conditions and operation of fire ventilation systems [24][25][26][27] and it is mentioned as a viable tool in some of smoke control standards [28].…”

Section: Numerical Modelmentioning

confidence: 99%

Smart Smoke Control as an Efficient Solution for Smoke Ventilation in Converted Cellars of Historic Buildings

2020

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The paper is focused on the topic of smoke control in a confined, underground cellar area of a historical building, that is undergoing conversion to a restaurant. Similar venues were host to some of the most devastating fires in history. We have investigated the performance of a novel solution, “smart smoke control (SSC)”, and compared its performance with “traditional” smoke venting solution. The investigation was based on CFD simulations performed in a commercial code ANSYS Fluent, modified with user-defined functions to include for the steering algorithm of the SSC. The simulation results for a traditional system were unsatisfactory, while the SSC removing substantially more smoke (approx. 50% more) has provided tenable conditions over the whole course of the analysis. The results indicate that smoke control solutions based on the adaptive performance of the smoke exhaust fan, based on the conditions within the protected premise, can be favourable for compartments with the limited size of the smoke reservoir or limited space available for ducts. These findings are also true for existing buildings, where it may be advantageous to replace the existing smoke control solution with SSC. Future investigations should include full-scale experiments, and improvements in the simple algorithms used so far.

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Empirical correlation derived by CFD simulation on heat source location and ventilation flow rate in a fire room

Cited by 19 publications

References 19 publications

A Study on the Reliability of Modeling of Thermocouple Response and Sprinkler Activation during Compartment Fires

A Study on the Reliability of Modeling of Thermocouple Response and Sprinkler Activation during Compartment Fires

3D Mapping of the Sprinkler Activation Time

Smart Smoke Control as an Efficient Solution for Smoke Ventilation in Converted Cellars of Historic Buildings

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