Modelling the Piston Effect in Subway Tunnels Using Fire Dynamics Simulator

Lanchava, Omar; Iliaş, Nicolae; Nozadze, Giorgi; Radu, Sorin Mihai; Moraru, Roland Iosif; Khokerashvili, Zaza; Arudashvili, Nino

doi:10.30638/eemj.2019.083

Cited by 18 publications

(16 citation statements)

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“…Under fire conditions, after a certain period of time, the influence of the operation of the fans on the ventilation flow decreases, despite the direction in which the temperature effect will be develop -to the side of increase the dynamic pressure; to the side of decrease the air density or both sides. Consequently, the collapse is the process of the emergence and distributing of dynamic pressure due by fire that is commensurable with fan's dynamic pressure [11][12][13][14]. We are noted that the dynamic pressure originated by the fire is algebraically summed up with the pressure developed by the ventilator.…”

Section: Collapse Of Ventilation Systemsmentioning

confidence: 99%

“…Buoyancy capacity of one gas towards the other is shown with dimensionless parameter, numeral of Richardson ( ), which shows the exchange of masses in between the streams and differs from the aforementioned Froude's number ( ), that indicates to the general form of the layer in ventilation stream. The results obtained through the numerical analysis for tunnel fires controlled by ventilation have been presented in the works [21][22][23].…”

Section: Positive and Negative Directions Of Ventilation Streammentioning

confidence: 99%

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Critical velocity analysis for safety management in case of tunnel fire

Lanchava

Iliaş

2020

MATEC Web Conf.

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Heat, smoke and other toxic products may spread along the tunnel, in both directions from the seat of fire, causing different kinds of damage to people. Anyway, underground fire causes complicated results, which is preventing factor for life rescue and evacuation, creating difficulties for firemen and life rescue crew. Analysis of the critical speed, which is necessary for the effective management of combustion products, has been made for tunnel fires with high heat release rate. The characteristic changes in the critical Froude number in the work are presented in accordance with the critical speed. Particularly, it was noted that the formula determining the critical speed requires knowledge of the average smoke temperature, while the formula for calculating the last value includes the value of the required critical speed. In order to overcome this, Froude’s critical number Frc=4.5 has been introduced, which is not the way of solution, as it directly means constant critical velocity for the fire of any power and accordingly, does not correspond to experimental data.

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Section: Collapse Of Ventilation Systemsmentioning

confidence: 99%

Section: Positive and Negative Directions Of Ventilation Streammentioning

confidence: 99%

Critical velocity analysis for safety management in case of tunnel fire

Lanchava

Iliaş

2020

MATEC Web Conf.

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“…The issue of the spread of uncontrolled air flow through the ventilation shafts, as we know, was not considered in the works of other authors. In the papers [2][3][4] deals theoretical analysis of the piston effect and results of numerical modelling in subway tunnels. In the papers [5,6] tables and graphs of changes in air flows generated by the piston effect are presented depending on the speed of the train and the degree of fill rate of the tunnel.…”

Section: ___________________________mentioning

confidence: 99%

“…In the papers [2][3][4] deals theoretical analysis of the piston effect and results of numerical modelling in subway tunnels. In the papers [5,6] tables and graphs of changes in air flows generated by the piston effect are presented depending on the speed of the train and the degree of fill rate of the tunnel. In the paper [7] it is noted that the piston effect is characterized by two phases: non-stationary and stationary.…”

Section: ___________________________mentioning

confidence: 99%

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Numerical simulation of air flow in short metro ventilation shafts caused by a piston effect

Iliaş

Lanchava

Nozadze³

2020

MATEC Web Conf.

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Protecting the infrastructure of the metro from unauthorized actions with the help of ventilation openings of the systems is one of the main security problems of this type of transport. This article discusses the problem of the dynamics of distribution of the mass flow rate of ventilation air in a two-component system “tunnel vertical ventilation shaft”, due to the piston effect of a moving train. The dependence of the mass flow rate of ventilation air passing in both directions in short ventilation shafts (up to 10 m), on the speed, location of the rolling stock and cross-sectional area of the ventilation shaft is investigated. It is shown, that at speeds of 10–20 m / s of rolling stock and sections of the ventilation shaft of more than 4 m2, the mass flow rate of air passing through the ventilation shaft must be taken into account with the mass flow rate of ventilation air in the transport tunnel for assessing the safety of the harmful aerosols. These processes can have a significant impact on the air quality of the underground infrastructure of the metro.

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Study of propagation of harmful factors of fire in short road tunnels with different inclinations

et al. 2021

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The paper considers the spread of combustion products caused by fires with different heat release rates: 5, 10, 15, 20, 30, 50 MW in up to 400 m long tunnels. The slope of the tunnels on numerical models is - 0, 1, 3, 5, 7, 9%. The cross-sectional area of the tunnel is 42.5m2. The paper describes the dynamic variability of damaging factors caused by the “chimney effect” such as carbon monoxide and temperature. Modeling was done with FDS software by using the finite volume method. The time of process modeling is 180 s. The minimum cell size of the finite volume is 0.25x 0.25 x 0.25m. The hearth of fire is in the central part of the tunnel. The obtained results are given in the plane of the central longitudinal section of the tunnel. The boundary condition is given as an increment of the dynamic pressure caused by the height difference between the portals in normal conditions. The dependence of fire-induced backlayering distance on the fire heat release rate and the increment of the dynamic pressure caused by tunnel inclination are studied. The theoretical results and those obtained by modeling of the backlayering distance and velocity are analyzed and compared. The locations of high-risk factors for each damaging factor along the tunnel are identified. Their quasi-stationary nature is described and the intervals of transient processes typical to each factor are determined in the course of modeling. It is advisable to use the obtained results to respond to emergencies caused by fire in relevant tunnels.

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Modelling the Piston Effect in Subway Tunnels Using Fire Dynamics Simulator

Cited by 18 publications

References 0 publications

Critical velocity analysis for safety management in case of tunnel fire

Critical velocity analysis for safety management in case of tunnel fire

Numerical simulation of air flow in short metro ventilation shafts caused by a piston effect

Study of propagation of harmful factors of fire in short road tunnels with different inclinations

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