Proposing a general formula to calculate the critical velocities in tunnels with different cross-sectional shapes

Savalanpour, Hamidreza; Farhanieh, Bijan; Afshin, Hossein

doi:10.1016/j.tust.2020.103798

Cited by 14 publications

(2 citation statements)

References 40 publications

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“…Through numerical simulations, Gannouni 8 investigated how the fire source height could affect the critical velocity V cr and found that the V cr was decreased with increasing the fire source height. The critical velocity was forecast by a modified formula proposed by Savalanpour et al 9 after studying the seven different cross-sectional shapes' critical velocities. The critical velocity of actual tunnels with various cross-sections was measured to confirm their correction formula.…”

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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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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“…CFD models, mainly numerical simulations, simulate air pollutants' diffusion and decay processes based on hydrodynamics under pre-defined conditions [22][23][24][25]. Previous studies have focused on identifying the key influencing factors of air pollutants inside tunnels and their mechanisms of action, including tunnel slope [26], building section size [27], natural wind [28], traffic wind [29], ventilation system [30], meteorological variables [31], nearby vegetation [32,33], particulate properties [34], etc. Song et al investigated utilizing mutual validation between field tests and model experiments.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Air Pollutants in Extra-Long Road Tunnel with the Combination of Pollutants Nonlinear Evolution and Machine Learning Method

et al. 2022

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The extra-long expressway tunnel has a high socio-economic effect on inter-regional development, with high traffic and strong traffic winds. Nevertheless, the impacts of the tunnel traffic volume on pollutant evolution are rarely considered. This study conducted a field measurement in a real-world extra-long highway tunnel for 578 days. For the first time, the nonlinear dynamics of traffic pollutants (CO, VOCs, NO2, PM2.5, PM10) were analyzed using the Multifractal Detrended Fluctuation Analysis approach. Using the Random Forest model, the impacts of traffic and environmental parameters on air quality were quantified. The findings indicated that COVID-19 had a considerable impact on tunnel traffic, although the variance in pollutant concentration was not very noteworthy. The bidirectional effect of traffic was the main reason for this phenomenon. The Canonical Correlation Analysis was unable to quantify the correlation between pollutants and environmental parameters. The pollutant concentration evolution has a steady power-law distribution structure. Further, an inverse Random Forest model was proposed to predict air pollutants. Compared with other prediction models (baseline and machine learning), the proposed model provided higher goodness of fit and lower prediction error, and the prediction accuracy was higher under the semi-enclosed structure of the tunnel. The relative deviations between the predictions and measured data are less than 5%. These findings ascertain the nonlinear evolutionary mechanisms of pollutants inside the expressway tunnel, thus eventually improving tunnel environmental sustainability. The data in this paper can be used to clarify the changes in the traffic environment under the COVID-19 lockdown.

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Effects of Fire Parameters on Critical Velocity in Curved Tunnels: A Numerical Study and Response Surface Analysis

Jafari,

Farhanieh,

Afshin

2024

Fire Technol

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Proposing a general formula to calculate the critical velocities in tunnels with different cross-sectional shapes

Cited by 14 publications

References 40 publications

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

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

Evaluation of Air Pollutants in Extra-Long Road Tunnel with the Combination of Pollutants Nonlinear Evolution and Machine Learning Method

Effects of Fire Parameters on Critical Velocity in Curved Tunnels: A Numerical Study and Response Surface Analysis

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