Numerical Investigation of Smoke Propagation in Road Tunnels Caused by a Burned Truck

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Taher Halawa
Keyword(s):  
Detailed Comparison ◽  
Fire Size ◽  
Air Jets ◽  
Longitudinal Ventilation ◽  
Road Tunnels ◽  
Low Visibility ◽  
Computational Fluid Dynamics Cfd ◽  
Ventilation Strategies ◽  
Research Gap ◽  
Special Case

Abstract The efficiency of smoke extraction for longitudinal and transverse tunnel ventilation systems was studied in this paper by conducting numerical simulations using computational fluid dynamics (CFD). The smoke was assumed to result from a fire initiated from a truck inside the tunnel. The most dangerous issue regarding the fire inside tunnels is smoke as it leads to low visibility and choking and may lead to death. The most important result of this paper refers to that the longitudinal ventilation design does not provide efficient smoke extraction compared to the transverse ventilation design as the air jets push the smoke in the downstream direction and then the smoke spreads randomly after the flow loses its momentum gradually. There is a big drop in the visibility for the longitudinal ventilation design that appeared many times and at many locations downstream the fire location. On the other hand, the transverse ventilation design provided more efficient smoke extraction as the jet fan upstream the fire is turned off while the supply fan downstream the fire is reversed to work as an exhaust fan. As a conclusion based on the findings of this paper, it may be said that the transverse ventilation design provided more safe conditions, lower contaminants concentrations, and higher visibility values compared to the longitudinal ventilation design. This work tends to add more information to minimize the research gap related to having a detailed comparison between the two ventilation strategies for a special case where the fire size is relatively large in a long tunnel.

scholarly journals Risk Analysis of Road Tunnels: A Computational Fluid Dynamic Model for Assessing the Effects of Natural Ventilation

2020 ◽  
Vol 11 (1) ◽  
pp. 32
Author(s):  
Ciro Caliendo ◽  
Gianluca Genovese ◽  
Isidoro Russo
Keyword(s):  
Natural Ventilation ◽  
Fluid Dynamic ◽  
Movement Time ◽  
Radiant Heat ◽  
Heat Fluxes ◽  
Maximum Heat ◽  
Road Tunnels ◽  
Maximum Heat Release ◽  
Computational Fluid Dynamics Cfd ◽  
Time Required

We have developed an appropriate Computational Fluid Dynamics (CFD) model for assessing the exposure to risk of tunnel users during their evacuation process in the event of fire. The effects on escaping users, which can be caused by fire from different types of vehicles located in various longitudinal positions within a one-way tunnel with natural ventilation only and length less than 1 km are shown. Simulated fires, in terms of maximum Heat Release Rate (HRR) are: 8, 30, 50, and 100 MW for two cars, a bus, and two types of Heavy Goods Vehicles (HGVs), respectively. With reference to environmental conditions (i.e., temperatures, radiant heat fluxes, visibility distances, and CO and CO2 concentrations) along the evacuation path, the results prove that these are always within the limits acceptable for user safety. The exposure to toxic gases and heat also confirms that the tunnel users can safely evacuate. The evacuation time was found to be higher when fire was related to the bus, which is due to a major pre-movement time required for leaving the vehicle. The findings show that mechanical ventilation is not necessary in the case of the tunnel investigated. It is to be emphasized that our modeling might represent a reference in investigating the effects of natural ventilation in tunnels.

Influence of the Pressure Load in the Efficiency of a Longitudinal Ventilation System in Road Tunnels

2009 ◽  
Author(s):  
Mo´nica Galdo-Vega ◽  
Carlos Santolaria-Morros ◽  
Jesu´s Manuel Ferna´ndez Oro ◽  
Katia Maria Argu¨elles-Di´az
Keyword(s):  
Momentum Transfer ◽  
Ventilation System ◽  
Operating Conditions ◽  
Traffic Density ◽  
Moderate Pressure ◽  
Pressure Gradients ◽  
Operational Parameters ◽  
Satisfactory Description ◽  
Longitudinal Ventilation ◽  
Road Tunnels

The longitudinal ventilation system (LVS) efficiency in road tunnels is conditioned by geometric and operational parameters. Typical geometric parameters are the length of the tunnel, its slope and the transversal section. All these factors are generally fixed and thus not modifiable in the regular operation of the facility. On the other hand, operational parameters, like the working fans layout, the environmental conditions or the traffic density are case-sensitive and susceptible to influence the baseline performance of the ventilation system. In the present study, different pressure gradients, established between inlet and outlet location of the jet fan influence, are analyzed. This static resistance is shown to have a significant impact on the momentum transfer established between the jet expansion and the bulk flow inside the tunnel. For moderate pressure gradients, the jet discharged from fan is relativity well-mixed, allowing to reach uniform flow conditions in the streamwise direction. When the adverse pressure gradients become severe, the high-velocity flow is blocked, unable to mix out in the inter fan spacing and losing spanwise uniformity. At critical conditions, large recirculation areas can be developed within primary flow structures, generating turbulence and important energy losses, and even inducing reverse flow at the tunnel exit. The extreme operating conditions of a longitudinal ventilation system in a road tunnel have been studied using a 3D numerical simulation. Preliminary analysis for grid sensitivity and election of an accurate turbulence closure were performed to guarantee a valuable modeling. Following, systematic computations over a cluster of PC’s were executed using the well-tested Fluent code. RANS modeling with RSM scheme allowed a satisfactory description of three-dimensional vortical structure in the recirculation zones, especially for adverse pressure gradients. At this point, numerical results have provided a comprehensive overview of the mechanism associated to the momentum transfer of the jet expansion, comparing the performance for zero-pressure gradients with those observed for adverse conditions. Also, this paper gives valuable information about practical limits of the LVS, advancing operational conditions that compromise the ventilation efficiency.

Current Safety Issues in Road Tunnel Construction

2020 ◽  
pp. 263-287
Author(s):  
Miguel Vidueira ◽  
Jiri Pokorny ◽  
Vladimir Vlcek
Keyword(s):  
Tunnel Construction ◽  
Road Tunnel ◽  
Significant Safety ◽  
Safety Devices ◽  
Safety Issues ◽  
Safety Standards ◽  
Longitudinal Ventilation ◽  
Road Tunnels ◽  
The Future ◽  
The Subject

The construction of road tunnels is an important part of road infrastructure. The operation of road tunnels has historically been accompanied by a number of extraordinary events. Fires are among the most dangerous ones. Individual countries create their own safety standards that mutually differ to a large extent. Some of the differences of the requirements for safety devices, including the requirements for their functionality, are compared and commented on in this chapter. Moreover, attention is paid to the use of asphalt surfaces on roads and sidewalks in tunnels. This chapter also describes the approach to fire ventilation in tunnels, one of the most significant safety devices. Special attention is paid to the choice of the strategy of longitudinal ventilation, which has been the subject of many discussions. This chapter outlines the possible directions for a solution in the future.

On the Use of Solid Curtains Near Smoke Extraction Vents to Control Smoke Spread Resulting From Fire in Road Tunnels

2020 ◽  
Vol 13 (3) ◽  
Author(s):  
Taher Halawa
Keyword(s):  
High Temperature ◽  
Release Rate ◽  
Control Strategy ◽  
Smoke Control ◽  
Smoke Spread ◽  
Peak Heat Release Rate ◽  
Road Tunnels ◽  
Low Visibility ◽  
Temperature Levels ◽  
Fire Accidents

Abstract The effectiveness of the smoke control strategy plays an important role in increasing safety levels when fire accidents occur in road tunnels. This paper introduces clarifications about how the efficiency of smoke extraction control using solid curtains can be increased by placing smoke extraction vents close to the solid curtains. The effect of adding a solid curtain with different heights and at various positions relative to a smoke extraction vent was studied in this paper. A 14.3% increase in the vent flowrate occurs at the time corresponding to the fire peak heat release rate when the distance between the solid curtain and the vent is equivalent to 90% of the tunnel height and when the solid curtain height is equal to 16% of the tunnel height. High temperature and low visibility conditions occur near the solid curtain at the smoke-trapped area when the smoke curtain height exceeds 40% of the tunnel height. Using a solid curtain positioned far away from the vent with a distance equals to 90% of the tunnel height and with a height in the range from 16% to 30% of the tunnel height achieves the best results in terms of suppression of smoke spread and attaining acceptable visibility and temperature levels at the region where the smoke is trapped by the solid curtain.

Theoretical Analysis of Longitudinal Ventilation System in a Road Tunnel for Predictive Control Based on Inertia Effect

2013 ◽  
Vol 639-640 ◽  
pp. 665-669 ◽  
Author(s):  
Zhen Tan ◽  
Zhi Yi Huang ◽  
Ke Wu ◽  
Lei Ting Xu
Keyword(s):  
Theoretical Analysis ◽  
Predictive Control ◽  
Ventilation System ◽  
Settling Time ◽  
Step Response ◽  
Inertia Effect ◽  
Road Tunnel ◽  
Longitudinal Ventilation ◽  
Road Tunnels ◽  
Co Concentration

Speed control of longitudinal ventilation systems in road tunnels is being combined with typical model predictive control (MPC) strategies which may bring huge energy saving potential to the system. Theoretical analysis of the inertia effect is presented based on the energy equation of one dimensional incompressible unsteady flow, step response model is chosen to describe the dynamic behaviors of the system. The results show that the effect of jet speed change on CO concentration is nonlinear within fan’s economical working range and the settling time of CO level has similar change trend with that of the flow field but is a little longer. The system settling time is longer when jet speed decreases than it increases and is related to the change extent of jet speed. The effect of traffic intensity on CO concentration can be regarded as linear disturbance to the system output. These results may provide useful indexes to control the tunnel ventilation system more economically and lay foundation for the application of predictive control strategy in the system.

scholarly journals Measurements of Discharge through a Pump-Turbine in Both Flow Directions Using Volumetric Gauging and Pressure-Time Methods

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4706
Author(s):  
Adam Adamkowski ◽  
Waldemar Janicki ◽  
Mariusz Lewandowski
Keyword(s):  
Operation Mode ◽  
Detailed Comparison ◽  
Pump Operation ◽  
Special Procedure ◽  
Pressure Time ◽  
Mode Of Operation ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Directions ◽  
The Impact ◽  
Low Uncertainty

This article presents the original procedures for measuring the flow rate using the pressure-time and the volumetric gauging method in the case of performance tests of a reversible hydraulic machine in either turbine or pump modes of operation. Achieving the lowest possible measurement uncertainty was one of the basic conditions during implemented machine tests. It was met using appropriate measuring procedures and high-class measuring equipment. Estimation of the uncertainty for both methods was made on the basis of an analysis consistent with current requirements in this respect. The pressure-time method was supplemented by the computational fluid dynamics (CFD) analysis that allowed reducing the impact of the pipeline complex irregular geometry on the uncertainty of flow measurement. Appropriate modifications of the calculation procedure enabled accurate measurements of flow during the pump mode of operation of the tested machine as well. The volumetric gauging method, thanks to a special procedure used for accurate measurement of the water level in the upper reservoir of the power plant, allowed measuring the discharge through the tested reversible machine with very low uncertainty. The obtained results allowed for a detailed comparison and mutual verification of the methods used to measure the discharge of the tested reversible machine in both modes of its operation. The most possible causes of obtained results are discussed and summarized in the paper. The need for further research was pointed out to explain the differences obtained and their influence on the accuracy of discharge measurement using the pressure-time method in pump operation mode.

scholarly journals Fire Size and Fire Spread in Tunnels with Longitudinal Ventilation Systems

2005 ◽  
Vol 23 (6) ◽  
pp. 485-518 ◽  
Author(s):  
R. O. Carvel ◽  
A. N. Beard ◽  
P. W. Jowitt ◽  
D. D. Drysdale
Keyword(s):  
Fire Spread ◽  
Fire Size ◽  
Longitudinal Ventilation ◽  
Ventilation Systems

scholarly journals Post-COVID-19 Sustainable Architecture Design Studio

2021 ◽  
Vol 5 (1) ◽  
pp. 59-68
Author(s):  
Pattaranan Takkanon
Keyword(s):  
Teaching And Learning ◽  
Design Studio ◽  
Architecture Design ◽  
Sustainable Architecture ◽  
New Normal ◽  
Hospital Design ◽  
Online Classrooms ◽  
Computational Fluid Dynamics Cfd ◽  
Ventilation Strategies ◽  
The Impact

COVID-19 outbreak has set the beginning of new normal in many parts of the world. The impact of COVID-19 was recognized in all sectors, including higher education. Many new ways of teaching and learning are taking place. Despite lockdowns and social distancing that transformed on-site classrooms to online classrooms, architecture design studio programs should also adapt and respond to the COVID-19 pandemic as well as contribute to society by taking the real-world projects. The architectural program of the Department of Building Innovation, Faculty of Architecture, Kasetsart University in Bangkok took the initiative in designing studio project programs to acknowledge the new normal. The programs were assigned to 2nd-year Sustainable Architecture Design Studio during the 1st semester (July-November) of the academic year 2020. Physical distancing, passive design, especially ventilation strategies, were the focus. Means to prove design performance include calculation and Computational Fluid Dynamics (CFD) methods. The paper shows results of the post-COVID-19 eco canteen and 50-bed hospital design programs.

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