Critical ventilation velocity for tunnel fires occurring near tunnel exits

Ventilation is an effective method for controlling smoke during a tunnel fire. The “critical ventilation velocity” u_cr is generally defined as the minimum velocity at which smoke is prevented from spreading against the longitudinal ventilation flow in tunnel fire situations. This study conducted small-scale experiments to investigate u_cr for situations when tunnel fire occurs near tunnel exits. The model tunnel was 4 m long, 0.6 m wide and 0.6 m tall, and the fires were located at 0.5 m, 1.0 m and 1.5 m from the tunnel exit. 6.3×6.3 cm² and 9.0×9.0 cm² square asoline fuel pans were used as fire source. Results show that u_cr decreases as the fire approaches the tunnel exit.     

Studies on buoyancy driven two-directional smoke flow layering length with combination of point extraction and longitudinal ventilation in tunnel fires

This paper investigates the buoyancy-driven smoke flow layering length (both upstream and downstream) beneath the ceiling with combination of point extraction and longitudinal ventilation in tunnel fires. A theoretical model is developed based on previous back-laying model with only longitudinal ventilation, with modified actual heat release rate, as well as modified upstream and downstream opposing longitudinal air flow velocities by the induced flow velocity due to point extraction. Experiments are carried out in a reduced scale model tunnel with dimensionless of 72 m×1.5 m×1.3 m. A LPG porous gas burner is used as fire source. The smoke flow layering length both upstream and downstream are identified based on temperature profiles measured along the ceiling, for different experiment conditions. CFD simulations with FDS are also performed for the same scenarios. Results show that with combination of point extraction and longitudinal ventilation, the smoke flow layering length is not symmetric where it is longer downstream than that upstream. The upstream smoke layering length decreases, while the downstream layering length increases with increase in longitudinal ventilation velocity; and they both decrease with increase in point extraction velocity. The predictions by the proposed theoretical model agree well with the measurements and simulation results.     

Experimental study of the effectiveness of a water system in blocking fire-induced smoke and heat in reduced-scale tunnel tests

A water system, consisting of several water mist nozzles, has been installed in a reduced-scale tunnel. Its effectiveness in blocking fire-induced smoke and heat is tested, with and without longitudinal ventilation. A total of 14 fire tests have been carried out, with 250 ml methanol in an iron tray (25 cm × 20 cm) as fuel. Temperatures have been measured by 30 thermocouples, located upstream and downstream of the fire location. The aim is to assess the effectiveness of the water system in preventing smoke spread and in reducing the temperature in the tunnel. Interaction of the water with the fire is avoided. The impact of water pressure, ventilation velocity and nozzle arrangement on the effectiveness in smoke blocking and temperature reduction is discussed. The result confirms that the water system effectively reduces the temperatures and prevents smoke spreading in the absence of longitudinal ventilation. However, strong longitudinal ventilation (0.8 m/s ventilation velocity in the reduced-scale tunnel, corresponding to critical velocity in full-scale (1:10) tunnel) reduces the effectiveness in blocking the smoke spreading by the water system, although the temperature reduction downstream the water system remains in place. Higher water pressure makes the cooling effect stronger, because more and smaller water droplets are injected into the tunnel. For a given level of water pressure level, the impact of the nozzle row configuration is small in the tests.     

Longitudinal ventilation for smoke control in a tilted tunnel by scale modeling

Longitudinal ventilation systems are commonly installed in new tunnels in large cities of the Far East including Mainland China, Hong Kong and Taiwan. Many tunnels are found in big cities and some of them are inclined at an angle to the horizontal. However, smoke movement in tilted tunnels is not fully understood. In some of the tunnels, the ventilation system was designed based on presumed smoke movement pattern without experimental demonstration. Smoke movement pattern in a tilted tunnel model was studied by using a scaled model. A 1/50 tunnel model of length 2 m with adjustable angle to the horizontal was constructed by transparent acrylic plastics. A small 0.097 kW propanol pool fire was used as the heat source combined with burning pellets generating smoke. A fan placed at the upstream end was used to create longitudinal ventilation. Different ventilation rates were set using a transformer to control or adjust the fan speed. Experiments were performed with the tunnel angle varying up to 30° to the horizontal. Effect of smoke screens was also studied. The observed smoke movement patterns indicated that the shape of the buoyant plume inside the tunnel depends on the tilted angle. Smoke would flow along the tunnel floor due to gravity. The bending angle of the plume depends on the tunnel angle. Tunnel inclined at greater angles to the horizontal would give larger amount of smoke flow. Smoke movement pattern for a tilted tunnel with smoke screens was observed to be very different from some design projects. All results will be reported in this paper.     

The effect of fuel area size on behavior of fires in a reduced-scale single-track railway tunnel

A set of experiments was carried out in a 1/9 reduced-scale single-track railway tunnel to investigate the effect of fuel area size on the temperature distribution and behavior of fires in a tunnel with natural ventilation. Methanol pool fires with four different fuel areas 0.6 × 0.3 m² (1 pan), 1.2 × 0.3 m² (2 pans), 2.4 × 0.3 m² (4 pans) and 3.6 × 0.3 m² (6 pans), were used in these experiments. Data were collected on temperatures, radiative heat flux and mass loss rates. The temperature distribution and smoke layer in the tunnel, along with overflow dimensions and radiant heat at the tunnel entrance were analyzed. The results show that as the fuel area enlarges, the fire gradually becomes ventilation-controlled and the ceiling temperature over the center of fire source declines. Burning at the central region of fire source is depressed due to lack of oxygen. This makes the temperature distribution along the tunnel ceiling change from a typical inverted V-shape to an M-shape. As observed in the experiments, a jet flame appeared at tunnel entrances and both the size and temperature of the flame increased with the enlargement of fuel area leading to a great threat to firefighters and evacuees in actual tunnel fires.     

Automatic fire detection in road traffic tunnels

Fire detection experiments in a road traffic tunnel were performed in the Runehamar test tunnel 5th–8th March 2007. The Runehamar test tunnel is a full profile road traffic tunnel, 1.65 km long, located outside Åndalsnes, Norway. The goal was to examinate smoke and heat detection systems to determinate what kind of principle best suited for detecting a fire in an early stage. The systems were tested during small Heptane pool fires, varying between 0.16 m² and 1 m², giving heat release rates from 0.2 MW to 2.4 MW accordingly, and one car fire of about 3–5 MW, and with wind conditions varying from 1.1 m s^?1 to 1.6 m s^?1. The size of the fires, were designed to be in the range from impossible to difficult to detect. The results were conclusive. Earliest detection of a car fire, fire starts inside, was by smoke detection given fixed limits (3000 μg m^?3). With open pool fires, or immediate flames, continues fibre optical heat detection systems was faster given the limits 3 °C/4 min.     

Investigation of the effect of tunnel ventilation on crib fires through small-scale experiments

This paper adopts a series of 1:20 scale tunnel experiments based on a series of large-scale tunnel experiments to study the influence of forced ventilation on fires. The small-scale tunnel has dimensions of 0.365 m (W)×0.26 m (H)×11.9 m (L). Cribs using a wood-based material provide the fuel source and forced ventilation velocities from 0.23 to 1.90 m/s are used. From the study of the measured heat release rate (HRR) and mass loss rate data it is found that the forced air velocity affects the fire spread rate and burning efficiency and further affects peak HRR values at different air velocities. A simple model to describe these influences is proposed. This model is used to reproduce the enhancement of peak HRR for cribs with different porosity factors noted by Ingason [1] and to assess the effects of using different length of cribs on peak HRR. The results from these analyses suggest that different porosity fuels result different involvement of burning surface area and result different changes in peak HRR. However, no significant difference to the enhancement on fire size is found when the burning surface area is similar. It is also found that the trend in the enhancement on fire size by using sufficiently long crib and available ventilation conditions matches the predictions of Carvel and Beard [2] for two-lane tunnel heavy goods vehicle fires.     

Full-scale experiment and CFD simulation on smoke movement and smoke control in a metro tunnel with one opening portal

Three full-scale model experiments were conducted in a unidirectional tube, which is a part of a metro tunnel with one end connected to an underground metro station and the other end opened to outside in Chongqing, PR China. Three fire HRRs, 1.35 MW, 3 MW and 3.8 MW were produced by pool fires with different oil pan sizes in the experiments. Temperature distributions under the tunnel ceiling along the longitudinal direction were measured. At the same time, CFD simulations were conducted under the same boundary conditions with the experiments by FDS 5.5. In addition, more FDS simulation cases were conducted after the FDS simulation results agreed with the experimental results. The simulation results show that the smoke temperature and the decay rate of the temperature distribution under the tunnel ceiling along the longitudinal direction increase as HRR increases. The smoke exhausts effectively from the tunnel under mechanical ventilation system, whether the emergency vent is activated as a smoke exhaust or an air supply vent. The operation mode of the mechanical ventilation system depends on the evacuation route.     

Influence of traffic force on pollutant dispersion of CO,NO and particle matter (PM2.5) measured in an urban tunnel in Changsha,China

Environmental safety issues and ventilation problems caused by the construction of urban tunnel have increasingly been attracting people’s attention. Previous studies in China have mainly focused on vehicle emissions and ventilation control technologies in road tunnels, resulting in a research gap on urban tunnel ventilation engineering design. Therefore, a detailed monitoring investigation was conducted from May 22 to June 2, 2013 in Changsha Yingpan Road Tunnel, China. The study aim was to measure the traffic characteristics, air velocity and the carbon monoxide (CO), nitrogen oxides (NO_x) and fine particulate matter (PM_2.5) concentrations in this tunnel, which has two lanes per bore and multiple ramps. Measurement results show that during the workday morning peak, the maximum traffic flow was 1560 passenger-car-unit/h per lane with vehicle speed around 33.6 km/h in the eastbound tunnel, the average air velocity was 3.07 m/s, and the proportion of the light-duty vehicles (LDV) was 97.3%. Under the traffic force (not open fan), the CO and NO average concentrations at the main tunnel outlet were 20.3 ppm and 1.65 ppm, respectively. The gas pollutant concentrations are effectively controlled within the multiple-ramps tunnel and the design air volume flow is noticeably reduced. The traffic air flow was found to provide 32.5% of the required air volume to dilute NO_x in blocked traffic condition (vehicle speed of 10 km/h). In addition, the PM_2.5 concentration is mainly affected by the value of background outside the tunnel. The result can provide a quantitative assessment method to support pollutant concentration control and contribution of requested air volume by traffic flow in urban complex structure tunnel.     

Experiments of evacuation speed in smoke-filled tunnel

Among tunnel fire safety strategies, evacuation speed in smoke, which is the basic evacuation performance characteristic, is one of the most important factors when assessing safety. An evacuation experiment in a full-scale tunnel filled with smoke has been done in order to clarify the relation between extinction coefficient up to Cs = 1.0 m⁻¹, which includes Cs = 0.4 m⁻¹ as a Japanese road tunnel fire prevention standard, and evacuation speed. The maximum, minimum and mean values of normal walking speeds are almost constant regardless of the extinction coefficient. As for the emergency evacuation speeds, the maximum speed is largely influenced by extinction coefficient, decreasing rapidly from 3.55 m/s at Cs = 0.30 m⁻¹ to 2.53 m/s at Cs = 0.75 m⁻¹ while the minimum and mean speeds are almost constant with a slight decrease as Cs increases. The maximum evacuation speed trends in the present experiments and those in Frantzich and Nillson (2003, 2004) and Fridolf et al. (2013), lie on the same decreasing logarithmic curve as a function of extinction coefficient.     

Safe velocity of on-fire train running in the tunnel

The safety of a running train on fire in a tunnel is a key issue for rescue operations, and the train velocity is mainly related to its safety. In this study, the relationship between the wind velocity and heat release rate (HRR), temperature field around the train, and flame/smoke pervasion rule were investigated under the conditions of variable train velocity, fire location, and fire source location. Beijing Metro was considered as a typical example, in which the safe velocity was estimated to be ∼41.83 km h⁻¹. Assuming the occurrence of fire at the center of the train, the numerical simulations of the flow field using the sliding grid of CFD were performed for a full-scale tunnel under different HRRs. When the fire source reached to the target section, the velocities of all the monitoring points rapidly increased. The velocities increased as the train tail arrived at the target section. The velocities at the measuring points increased with the increase in height, excluding the value of the position with a distance of 0.025 m from the tunnel ceiling. The average temperature and concentration of smoke in the annular space between the train and tunnel ceiling had the minimum values when the running train on fire moved with a speed of 45 km h⁻¹. Thus, the safe velocity of a subway train on fire should be managed between 41.83 km h⁻¹ and 45 km h⁻¹.     

Determination of dynamic model parameters of smoke detectors

A simple model for the dynamic response of point-type smoke detectors is described. The model is based on two independent parameters: the characteristic length and the static response threshold. Experimentally determined values of the parameters for six commonly used point-type smoke detectors are reported. In the tests the free stream flow velocity was varied in the range of 0.2–0.8 m/s and the rate of rise of smoke density in the range of 0.1–2 dB/ms. The model parameters were determined from the experimental data by using the least squares fitting with regularisation. The characteristic length was found to vary in the range of 2–10 m indicating a smoke entry time constant in the range of 10–50 s at a flow rate of 0.2 m/s typical of smouldering fires. The response of photoelectric detectors was described by the model reasonably well. In the case of ionisation detectors, significant deviations were found. A method of using the model in fire safety engineering calculations is also presented.     

An experimental study on the intermittent extension of flames in wind-driven fires

Experiments were conducted to study the intermittent extension of flames from wind-driven line fires using stationary burners. These fires are thought to share similar features with propagating wildland fires, where forward pulsations of flame have been observed to quickly ignite material far ahead of the mean flame front. However, stationary burners offer the ability to study the movement of the flame and its heating processes in greater detail than a spreading fire. In these stationary experiments, propane gas was used as a fuel with different burner sizes, 25–30 cm wide and 5–25 cm long in the direction of the flow. A specially-built wind tunnel was used to provide a well-characterized laminar flow for the experimental area. The free-stream flow velocity, measured by a hot-wire anemometer, ranged in the experiments from 0.2 to 2.7 m/s. The shape of the flame was measured using a high-speed video camera mounted perpendicular to the apparatus. A method was developed to track the extension of the flame close to the surface, simulating flame contact with unburnt fuel downstream of the fire. This extension length was then measured frame by frame and frequencies of flame presence/absence determined as a function of downstream distance. The location of maximum pulsation frequency, x_max, for each burner/wind configuration, was obtained using a level-crossing approach (essentially the variable-interval time-average (VITA) method). Further study indicates that x_max can be well estimated using mean flame properties. Probability distributions describing the location of the flame over time also showed that, the probability the flame extends far beyond the mean flame front is sensitive to increasing ambient winds and fire size.     

Gas temperatures in heavy goods vehicle fires in tunnels

Large-scale fire tests were carried out with heavy goods vehicle (HGV) cargos in the Runehamar tunnel in Norway. The tunnel is a decommissioned, two-way-asphalted road tunnel that is 1600 m long, 6 m high and 9 m wide, with a slope varying between 0.5% uphill and 1% downhill. In total four tests were performed with fire in an HGV set-up and a longitudinal ventilation flow of approximately 3 m/s. In three tests, mixtures of different cellulose and plastic materials were used; in the fourth test a commodity consisting of furniture and fixtures was used. In all tests the mass ratio was approximately 82% cellulose and 18% plastic. A polyester tarpaulin covered the cargo.One purpose of the large-scale tests was to obtain new relevant gas temperature-time data from large-scale HGV fires in tunnels. There is presently a lack of such information for road tunnels. The maximum heat release rates produced by the four different fire loads varied between 66 and 202 MW resulting in maximum gas temperatures at the ceiling ranging between 1281 and 1365 °C. A comparison with literature values shows that the gas temperatures obtained here are uniformly higher than those obtained in other similar large-scale test series conducted using solid materials. A mathematical correlation of a temperature–time curve is given and this is the best representation of the measured temperature and a combination of frequently used temperature curves for tunnels (the HC curve and the RWS curve).     

纵向通风与竖井自然排烟下隧道火灾烟气特性实验研究

中国逐渐发展成为世界上隧道和地下工程最多的国 家,其长隧道数量和长度跻身世界前列。据统计,火灾中85%的 人员死亡是由热烟气造成的,目前隧道中采用较为广泛的排烟系 统有纵向排烟系统、集中排烟系统和横向排烟系统,而针对长隧道 来说,我国广泛采用的是竖井式纵向通风,因此,研究纵向通风与 竖井排烟综合效应下隧道火灾烟气流动特性及温度分布规律具有 重要意义。本文建立了1：10 缩尺寸竖井隧道模型,主隧道长度 16.5 m,宽度1.3 m,高度0.65 m;竖井通过排烟横通道与主隧道 连接,排烟横通道设置在主隧道侧面中部,尺寸为1.2 m 长、0.6 m 宽、0.4 m 高;竖井横截面为半径0.6 m 的1/4 圆,高4.6 m。在 竖井隧道模型中开展了一系列油池火实验,选取2 种方形燃烧池 （20 cm×20 cm、23 cm×23 cm）作为火源,设置2 个纵向火源位置 （位置A：火源中心线与排烟横通道中心线距离0.375 m;位置B： 火源中心线与排烟横通道中心线距离1.375 m）,7 种纵向通风风 速（0,0.18,0.27,0.35,0.44,0.52,0.69 m/s）,定量分析不同工 况下温度分布及烟气逆流长度。研究结果表明：当无纵向通风时, 火焰与隧道地板垂直,且呈轴对称形态;当有纵向通风时,火焰向 下游偏移,且纵向通风风速越大,火焰向下游偏移越明显;当纵向 通风风速为0 m/s 时,由于竖井的存在,火源上、下游两侧烟气温 度分布并非对称,火源下游（竖井侧）烟气温度下降速度较快,与单 洞隧道烟气温度分布明显不同;随纵向通风风速增加,烟气逆流长 度和烟气温度减小,而最大温度偏移距离整体呈增加趋势;当无量 纲纵向通风风速v′＜0.19 时,主隧道最大温升△Tmax 与Q2/3/ Hef 5/3 呈正比,而当无量纲纵向通风风速v′＞0.19 时,主隧道最大 温升△Tmax 与Q? /(vb1/3Hef 5/3)呈正比,但常数系数均小于Li 等预 测模型中的常数系数;竖井隧道内无量纲纵向烟气温度分布符合 Fan 和Ji 等建立的纵向温度衰减模型,衰减系数k′在1.36~1.63 范围内变化,但其值明显大于单洞隧道纵向温度衰减系数k′;另 外,当火源位于位置A 时,最大烟气温度低于火源位于位置B 时 的最大烟气温度,无量纲纵向烟气温度衰减速度慢于火源位于位 置B 时衰减速度。     

Velocity and temperature attenuation of a ceiling-jet along a horizontal tunnel with a flat ceiling and natural ventilation

A series of fire tests was conducted in a small-scale tunnel with dimensions of 10.0 m (L) × 0.75 m (W) × 0.45 m (H) and a rectangular cross-section. Detailed measurements of the velocity and temperature within a steady fire-driven ceiling-jet running along the centre of the ceiling were conducted.Referring to a theoretical derivation process described in the literature as a starting point, correlations representing the velocity and temperature attenuation along the tunnel axis were developed.The values of the coefficients included in the developed correlation for the velocity attenuation were measured using a particle image velocimetry system during the experiments conducted in the small-scale tunnel. The value of the Stanton number was determined by considering the ceiling-jet thickness, which was derived from the velocity distribution. The values of the coefficients included in the developed correlation for the temperature attenuation were also determined based on experimental results described in the literature, which were obtained in a large-scale tunnel constructed using good heat insulation properties.Through these correlations developed for the velocity and temperature attenuations along the tunnel axis, the variation in the Richardson number of the ceiling-jet based on the distance from the fire source position along the tunnel axis was examined, and the position where the ceiling-jet changed from a shooting flow to a tranquil flow was determined. The boundary positions between the shooting and tranquil flows were determined using correlations between the velocity and/or temperature attenuation, which were compared with the variation in the Richardson number along the tunnel axis to verify their appropriateness.     

Ceiling-jet thickness and vertical distribution along flat-ceilinged horizontal tunnel with natural ventilation

A series of fire tests was conducted in a 10.0 m (L) × 0.75 m (W) × 0.45 m (H) model tunnel with a rectangular cross section, and detailed measurements were taken of the temperature and velocity within a quasi-steady state fire-driven ceiling-jet running along the centre of a ceiling.The ceiling-jet thickness was defined as the distance from the tunnel ceiling to the point where the temperature and/or velocity dropped to half of their maximums. Correlations to represent the variation in the ceiling-jet thickness along the tunnel axis were developed with the aid of a theoretical approach. The coefficients included in these correlations were determined based on the experimental results obtained. It was found that the ceiling-jet thickness derived from the temperature was 1.17 times greater than that from the velocity in the tranquil flow region.In the tranquil region, both the velocity and temperature showed top-hat distributions, with a bulging shape from the apex of the distribution towards the tunnel floor. A cubic function and coordinate transformation were applied to develop empirical formulae for the temperature and velocity distributions, which were represented by the dimensionless distance from the tunnel ceiling and dimensionless temperature rise and/or velocity at a given distance from the fire source. The correlation developed for the temperature distribution was compared with the results of large- and full-scale tunnel experiments, which verified its applicability.     

Possibility of using roof openings for natural ventilation in a shallow urban road tunnel

Naturally ventilated urban vehicular tunnels with multiple roof openings have increased in China. Unnecessary gas (polluted air or fire smoke) are expected to be exhausted out through openings. Whether its safety standards can be satisfied or not still needs to be verified. In this paper, a safe CO concentration was firstly discussed, and a heat risk level of very high to extreme up to 46 °C was given. Secondly, a real 1410 m tunnel was proposed, and a 1/10 scale model tunnel was reproduced. Ambient winds of 0.95 m/s in prototype and 0.3 m/s in model were considered. Under normal traffic test, a track circuit was constructed with model vehicles moving on it to form traffic wind, and once the air velocity was larger than 0.31 m/s, the airflows were found to be not relevant to the Reynolds number. The traffic winds were weakened by openings. For three of all tested traffic, the actual air velocities were larger than the required ones, so its air qualities were satisfied. In firing test, two sets of burning experiments were conducted with which the heat release rates (HRR) were 8.35 kW and 13.7 kW. Large amounts of smoke were exhausted out of openings, and the high-temperature was not significant. Full-scale numerical simulations were carried out to verify the experimental results respectively using Fluent 6.0 for normal traffic and FDS 4.07 for firing. The simulations were compared well with the experiments. Further FDS simulations show that the openings’ mass flow rates are influenced little by ambient temperature; with the increasing length of the buried section, much smoke accumulate inside leading to a high temperature; having 4–5 openings in one shaft group is oversize in the actual engineering design.     

Smoke concentrations inside and outside of a corridor-like enclosure

This work presents smoke measurements and correlations inside and outside of a corridor-like enclosure fires in order to determine the effects of burning on smoke concentrations inside and outside the enclosure. Thirty eight experiments were performed in a three metre long corridor-like enclosure having a cross section 0.5 m×0.5 m, door like openings in the front panel and a gaseous burner located near the closed end. Smoke concentrations were measured at two locations inside the enclosure and also in the exhaust duct of a hood collecting the fire gases from the enclosure. It was found that smoke concentration in the exhaust duct decreased whereas smoke concentration inside the enclosure increased after the flames started moving towards the opening and external burning occurred. This increased smoke concentration inside the enclosure was caused by reversion of the flow pattern inside the enclosure after the flames moved past a point towards the opening. Namely, the flow pattern changed direction behind the flame front in the sense that hot gases in the upper layer were travelling backwards towards the closed end of the corridor thus contributing to smoke increase inside the enclosure. This change of flow pattern was confirmed in all experiments by bidirectional probe velocity measurements in the upper and lower layer as well as by oxygen concentrations and temperature measurements inside the enclosure. These results are useful for CFD validation and specifically applicable for assessing smoke hazards in corridor fires in buildings where smoke concentrations can be much larger than anticipated owing to leakage to adjacent rooms behind a moving flame front.     

CFD analysis of a realistic reduced-scale modeling equipped with axial jet fan

Typically, in the experimental scale road tunnel model, the air flow induced by ventilation system is provided by an external fan. In this paper, the authors have numerically simulated full and reduced-scale tunnel in order to evaluate the possibility to realize a reduced scale of a road tunnel model with a realistic ventilation system consisting of impulsive jet fans.In particular, two different types of longitudinal ventilation systems were considered, traditional and alternative. The last one was equipped with jet fans that have the inlet/outlet sections inclined at a fixed pitch angle (α=6°) toward the tunnel floor. The jet fan was simulated as a simple momentum source that provides a pressure rise (pressure drop) across them as a function of the outflow air velocity.The analyzed tunnel consists in a 800 m one directional bore with circular cross section 5.05 m radius; the jet fans were installed at 5.67 m from the floor. Furthermore a burning Heavy Good Vehicle (HGV), placed at 450 m far away the tunnel entrance, was considered. To simulate numerically the burning vehicle, the species transport equation combustion model with Eddy-Dissipation-Concept (EDC) model was adopted.In order to create a reduced-scale model from a full scale, Froude method was applied to preserve geometrical, kinematical and dynamical similitude. Temperature and axial velocity profiles, in different tunnel sections for both considered models (full and scaled) and ventilation systems, were provided. The numerical results showed a good agreement for the both ventilation systems.