Estimation of the effects of water mist system on the tunnel critical velocity due to smoke cooling

Deng, Tao; Norris, Stuart; Sharma, Rajnish N.

doi:10.1016/j.tust.2021.104299

Cited by 9 publications

(2 citation statements)

References 35 publications

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“…Similar results were obtained by Li and Ingason [94], who emphasized the effect of ventilation on the effectiveness of water suppression systems. Model-scale simulations have been applied to study the interaction of water mist with other safety systems, such as evaluating critical velocity with and without mist suppression and using the ratio between the water evaporation rate and fire burning rate as a fundamental parameter [95,96]. The designed direction of nozzles can also influence the suppression results [97], along with the balance of ventilation velocity and the water mist setting [98].…”

Section: T31 Water Mist and Water Spraymentioning

confidence: 99%

A Critical Review of Fire Tests and Safety Systems in Road Tunnels: Limitations and Open Points

Lombardi

Berardi

Galuppi

2023

Fire

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Fire tests are used to determine whether fire protection products meet the minimum performance criteria set out in codes and legislation, as well as to certify these products. Experimental large-scale fires are used to test the performance of safety systems in tunnels, which are confined environments with a high probability of accidents and significant consequences due to the evolution of the event and whether there is the capability of counteracting it by safety measures. In this study, we conducted a systematic literature review following PRISMA guidelines. We searched the Scopus and Web of Science databases for publications from 2013 to 2022, resulting in a selection of 72 articles. An analysis was conducted on the following main topics: tunnel fires, fire characteristics (measured variables, spread, and smoke), model-scale tests, automatic shutdown systems, and ventilation solutions. One of the most important contributions of this study is the suggestion that fire tests represent an effective method not only to prevent fire events in tunnels but also to ensure the resilience of the infrastructure. Based on this state-of-the-art literature review, future tunnels could be designed by linking new smart technology and artificial intelligence to create interactive and high-performing safety systems.

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Section: T31 Water Mist and Water Spraymentioning

confidence: 99%

A Critical Review of Fire Tests and Safety Systems in Road Tunnels: Limitations and Open Points

Lombardi

Berardi

Galuppi

2023

Fire

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“…Under the studied conditions, the water droplets absorbed around half of the heat that the fire source was giving out. Deng et al 15 derived one theoretical approach to estimate the decrease in critical velocity in small fires by using the concept of global energy balance and the critical Froude number theory. Through numerical simulations and full-scale experiments, they proved the Froude number theory can be applied to water mist systems.…”

Section: Introductionmentioning

confidence: 99%

Influence of the water spray particle diameter and flow rate on the smoke flow and the back-layering in tunnels with longitudinal ventilation

Gao,

Wang,

Cai

et al. 2023

Indoor and Built Environment

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When there is a fire in a tunnel, the heat released by the combustion is difficult to dissipate and the temperature inside the tunnel would rise rapidly. Longitudinal ventilation (LV) has been commonly adopted as the smoke control strategy in tunnel fires, which is essential to safeguard the tunnel structure and the trapped people. Besides the smoke control method by LV, the water mist system (WMS) can provide a powerful cooling effect for the high-temperature smoke in the tunnel. This article aims to investigate the impact of WMS on the smoke back-layering (BL) length with LV and the mutual effect process between the smoke spread and the WMS. The findings show that the BL length is restricted more effectively by the combined action of water mist and LV. Upon activation of the WMS, the water mist’s effect inhibits the smoke’s ability to spread upstream and causes the smoke layer to settle down, which disturbs the stability of the smoke layer. An unstable layer of smoke is more likely to be blown downstream by longitudinal ventilation. All water mist particle diameters show a significant reduction in smoke back-layering with an increased flow rate. The BL length would gradually reduce as the particle diameter is decreased. The tendency of flow rate and particle diameter on the BL length shows similar effects to the critical velocity ( Vcr). The Vcr is reduced with the rising flow rate and increased with expanding particle diameter.

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Improving the fire-extinguishing effect of pneumatic extinguishers with airflow-spray synergistic jet: Investigation of nozzle position and number of nozzles

Chen

Zhu

et al. 2023

Case Studies in Thermal Engineering

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Estimation of the effects of water mist system on the tunnel critical velocity due to smoke cooling

Cited by 9 publications

References 35 publications

A Critical Review of Fire Tests and Safety Systems in Road Tunnels: Limitations and Open Points

A Critical Review of Fire Tests and Safety Systems in Road Tunnels: Limitations and Open Points

Influence of the water spray particle diameter and flow rate on the smoke flow and the back-layering in tunnels with longitudinal ventilation

Improving the fire-extinguishing effect of pneumatic extinguishers with airflow-spray synergistic jet: Investigation of nozzle position and number of nozzles

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