Smoke Management System Research Articles

Improving terminal fire safety with minor impact on operational continuity using performancebased design

Bologna Airport is dealing with a significant increase in passenger flows. Even after the COVID-19 pandemic, traffic volume is rapidly growing and will soon exceed previous traffic records. Against this background, the airport has supported new infrastructure investments in order to both optimise existing terminal functional use and to comply with stringent fire safety requirements on terminal buildings, in line with new Italian airport safety legislation. In particular, Bologna Airport has planned a short-term investment specifically regarding the Terminal Smoke Management System, consisting of smoke vents and smoke extraction fans that work in coordination with fire detection systems and other fire suppression systems already installed into the building, and with the Terminal Fire Emergency Plan. For this kind of system, the Italian laws and standards set a basic prescriptive approach that simplifies the design phase with conservative solutions, with invasive, costly and time-consuming installations that are generally not compatible with operational continuity needs for terminal areas. As an alternative, a performance-based design approach is allowed for more customised solutions, focusing more closely on the design phase and terminal functional strategy. This case study shows how Bologna Airport implemented a performance-based design approach in order to minimise the impact of the new system installation throughout the terminal, optimising the engineering solutions with no constraints from the terminal functional flexibility point of view as well as saving over 75 per cent costs and construction time, compared to a traditional prescriptive approach.

Optimization of an automated smoke control system in an industrial atrium

Pool fires are the most common hazard in many industrial applications. Therefore, automated fire control systems and occupational safety design codes and procedures are of major importance in industrial building systems design. Smoke is the main factor that causes deaths and casualties in fires. Thus, fire safety engineering (FSE) considers smoke management system as one of the most important factors. In this study, smoke generation during pool fire is numerically simulated to optimize the smoke management system. The smoke and temperature distributions inside a mechanically ventilated atrium are simulated using a computational fluid dynamic (CFD) transient model after initiating a diesel pool fire in the worst case scenario. Four numerical models are simulated and their results are compared to choose the model that optimizes smoke control. The models enable better approximations of the underlying physical phenomena in smoke transport for a single phase gas mixture. A velocity field approach is predicted using a turbulent standard k-ε model to study the domain with smoke plume. The ability to demonstrate and predict the flow field inside the atrium while the roof exhaust fans are operating is also investigated. The study aids in smoke management systems' design and helps to better understand of smoke plume behavior inside large spaces.

Numerical study on smoke exhaust system in a mall with mechanical make-up techniques

This paper shows a numerical investigation on smoke management techniques inside a large building. Fifteen numerical simulations were carried out using fire dynamic simulator FDS software. The effect of adding a mechanical exhaust louver on the roof inside the building is studied. This was carried out by varying the exhaust ACH and the configuration of the exhaust openings. Also, the effect of injecting fresh air into the building was examined by investigating the effect of changing the make-up air ACH and the location of the make-up air. All cases were analyzed by studying the smoke layer height, mean soot density and the mean temperature of smoke.It was observed that the smoke hazard decreases by increasing ACH, using multiple exhaust points, and adding make-up air. As compared to no smoke management, this enhancement reaches 71.18% for the smoke layer, 31.6% lowering the average temperature, and 38.4% decreasing the average soot density. These results were achieved when six opposed supply louvers and one exhaust louver were used for the smoke management system.

A Study of the Effect of Make-Up Air Velocity on the Smoke Layer Height with Symmetric Openings in Atrium Fires

This paper presents full-scale test results and CFD modeling of smoke conditions in atrium fires in the case of symmetric make-up air opening arrangements. The atrium used for the experiments was equipped with a smoke management system capable of exhausting 132 m3/s. Thermocouple trees were installed to measure the temperature along the height of the atrium. The N-percentage method was used to determine the smoke interface height from the measured temperature profiles. Make-up air velocities of 1 m/s, 1.5 m/s and 2 m/s were selected to investigate the effect of make-up air velocity on the smoke interface height in the case of 4-side and 2-opposite side openings. The fire size varied from 1 MW to 5 MW to cover the effect of small, medium and large fires. FDS was also used to simulate the atrium fires in order to compare the predictions with the full-scale test results and evaluate the accuracy of the developed correlations. Results show that the limit of 1 m/s is too restrictive in the case of symmetric opening arrangements. A correlation is proposed based on the full-scale test results that can be used to modify the smoke layer height obtained using plume equations so that the effect of make-up air velocity on the smoke layer height is considered.

A STUDY OF THE FIRE SMOKE PROPAGATION IN SUBWAY STATION UNDER THE EFFECT OF PISTON WIND

A running traffic train induces piston wind in the subway. The influence of piston wind on fire smoke propagation in subway is investigated numerically. The flow field structure in fire platform, temperature contours and velocity profiles at certain positions are obtained at various scenarios respectively. Three methods are adopted to reduce the impact of piston wind on smoke layers. Results show that large-scale vortexes and tremendous horizontal inertial force would be produced under the influence of piston wind; and that smoke stratification would be broken totally under its influence, therefore toxic gas would spread to subway hall through stairs. So the former smoke management system in a subway station becomes less effective. Results also show that combination of enhanced the volume flux of pressurization at the subway hall and lowering the height of smoke screens around stairs are necessary to restrict hazard smoke on the floor on fire. The bypass wind tunnel and ventilation shaft are useful to attenuate the magnitude of piston wind.

CFD analysis of smoke transport inside an aircraft cargo compartment

This paper presents a CFD model for smoke dissipation inside a 707 cargo compartment under fire conditions. The model can provide information on temperature distribution and smoke transport. The mass conservation, momentum, energy, and turbulence model equations were solved using the finite-volume method with a passive scalar approach to model the smoke (CO, CO2 and soot) transport. In order to validate the adopted procedure, the numerical results are compared with both experimental data and also CFD results provided by Federal Aviation Administration developed code. Temperature profiles along the ceiling cargo compartment exhibit a buoyant plume pattern that rises directly above the localized fire source, strikes the ceiling, and creates a ceiling jet flow. Predictions obtained for smoke concentration are in good agreement with experimental results. It is shown that the proposed method should be useful for designing a smoke management system and the CFD smoke transport model has potential to satisfy the certification process.

Smoke Management System Design for Airport Terminal

“Open Cabin” includes a solid roof which has enough fire resistance, covers over the entire region whose fire load is relatively high, such as commercial building with a large area. Performance design using “Open Cabin” concept of big space, is to protect areas whose fire load is relatively high from fire using the local fire protection measures (automatic alarm system, automatic sprinkler system, fire compartment and smoke resistance facilities), in order to make up fire protection measures which cannot be set in full range within big space. Then there is no need to separate big space physically for limiting the spread of fire and smoke.

Numerical study on smoke movement driven by pure helium in atria

The hot smoke test is often used for commissioning fire smoke management system in atrium buildings, in which liquid fuel is burnt to generate a buoyant plume mixed with artificial tracer smoke to model a fire smoke. The method is usually costly and often causes safety concerns. This paper studied an alternative method of using a cold smoke test, in which pure helium is used to create the buoyant plume. A method was developed to determine the supply rate of pure helium necessary to achieve the same buoyancy effect as that of the corresponding hot smoke test. Computational fluid dynamics (CFD) simulations of the helium smoke tests were conducted and compared to the measured hot smoke tests in a full-scale naturally ventilated atrium and a sub-scale atrium with mechanical ventilation. A new method was added in the CFD model to track the smoke layer height for the simulations of helium smoke based on the concentrations of smoke and helium. It is found that the predicted smoke layer heights based on the mass fractions of the tracer smoke are generally close to the measured ones in the hot smoke tests of different heat release rates. A non-dimensional temperature in the hot smoke test is also found closely related to the dimensionless helium concentrations in the helium smoke test for the atria modeled. Although the consumption of pure helium for a full-scale helium smoke test can be very high, it is promising to use the pure helium smoke test in the lab-scale experiments as the preliminary tests of full-scale and/or lab-scale testing of real fires.

Preliminary Study on Exhaust Efficiency of Smoke Management System in Tunnel Fires

Exhaust efficiency in tunnel fires with mechanical means was discussed. Heat exhaust efficiency and smoke exhaust efficiency were defined and studied under two different exhaust modes (longitudinal exhaust and transverse exhaust) respectively. Exhaust efficiency depends on smoke generation rate, exhaust rate, heat loss through walls of tunnel, configuration of extraction installations and so on. Under smoke extraction, smoke exhaust efficiency equals 1 if a quasi-steady vented stage without upstream outflow forms, otherwise smoke exhaust efficiency is less than 1. Heat exhaust efficiency is always less than 1 since part of the heat released by the fire is lost through the solid boundaries of tunnel by radiative and convective heat transfer between the smoke and ceiling lining. Based on experimental data obtained from a series of fire tests in a model tunnel, heat exhaust efficiency was estimated and influencing factors were discussed. In tunnel fires with transverse mechanical exhaust system, heat exhaust efficiency varies from 20% to 50%. Heat exhaust efficiency increases along with the reduction of the number of exhaust inlets turned on while extracting and decreases along with the increase of the area of exhaust inlet. However, quantitative influence of inlet position on exhaust efficiency still need further study and will be reported later.

Engineering Numerical Simulation on the Amount of Make-up Air for Mechanical Smoke Exhaust in Atrium

Smoke is one of the major hazards on to the occupants in atrium fires. It is commonly accepted that the smoke should be timely exhausted. Make-up air must be supplied simultaneously to the atrium in order to keep the smoke exhausting efficiency. The amount of make-up air therefore acts as a key factor of the smoke management system design. Numerical simulations were performed in this study to investigate the impact of make-up air on the smoke exhausting efficiency. Results show that when a 30% or more of the amount of smoke exhaust for make-up air is able to be kept smoke exhausting process efficient. The “as much as possible” concept for make-up air should not be considered regarding the research results.

A critical study on fire-induced aerodynamics of balcony spill plumes

Balcony spill plume is one of the main plume forms in an atrium fire, its thermal behavior which is important to the designers for the smoke control system design is still not well understood now. The fire-induced aerodynamics of balcony spill plume would be studied by the numerical method in this paper. Some uncertainties relating to the available calculation methods for the smoke production rate would be reexamined. Numerical results indicated that using an entrainment coefficient 0.11 would be better than 0.16 in describing the entrainment behavior, end effect should not be ignored for the plume being not two-dimensional (2-D). Suitable empirical spill plume equations would be recommended for the smoke management system design.

Using FDS to Simulate Smoke Layer Interface Height in a Simple Atrium

This study examines the possible effects of various make-up air supply arrangements and velocities in an atrium smoke management system. Variations include velocities ranging from 0.5 to 3.0 m/s. The arrangement of make-up air supply injection points include symmetrically located vents placed low in the spaced, an array of vents distributed from the floor to the ceiling, and asymmetrically located vents. Fire Dynamic Simulator version 4.06 is applied to simulate ten scenarios in a 30.5 m cubical domain with a fire source simulating a stack of pallets with an approximate peak heat release rate of 5 MW. Results show that make-up air supply velocities should be diffused such that little to no velocity effects reach the fire. Make-up air should be supplied to the fire symmetrically for the best chance of not disturbing the fire plume. Disturbing the fire and smoke plume results in a significant increase in the smoke production rate, as evidenced by a deeper smoke layer.

Mass flow rates across layer interface in a two-layer zone model in an atrium with mechanical exhaust system

Two-layer zone models are commonly used for studying smoke filling in enclosures. There, a clear distinct layer of hot smoke lies above a cool air layer. No mixing of air mass is assumed across the layer interface plane. Based on that, empirical equations are derived in designing atrium smoke management system guides such as NFPA-92B. As observed physically, there might be mass flow across the layer interface of the two layers in the atrium when a mechanical smoke exhaust system is operating. Such a two-layer picture might not be resulted in a big hall. In this paper, exchange mass flow rate across the two layers will be studied based on earlier experimental data on atrium hot smoke tests. It is found that for most of the tests, the mass flow rate across the smoke layer interface can be 30% of the mass exhaust rate of the smoke exhaust system.

Evacuation with smoke control for atria in green and sustainable buildings

The concepts of green buildings and sustainable buildings are promoted actively in the developed countries. Targets are on protecting the environment, using less energy through natural ventilation provisions and daylight utilization, developing better waste management and taking water conservation into account. Architectural and building design, electrical and mechanical systems, and building management have to be upgraded. However, there are problems in dealing with fire safety, especially in complying with the existing prescriptive fire codes. An obvious example leading to hot arguments is the green or sustainable buildings with an atrium. Smoke spreading would give problems and evacuation design under smoke was identified to be a key issue. Providing more emergency exits might give a faster evacuation time, but would give security problems. An alternative solution is to install a smoke management system to keep the smoke layer high. Better designs can be achieved by integrating the evacuation time with the smoke filling time under different scenarios. Evacuation design can be improved by installing a smoke exhaust system. System performance by fire safety management would provide adequate safety. This point will be demonstrated in this paper.

A Preliminary Discussion on Selecting Active Fire Protection Systems for Atria in Green or Sustainable Buildings

Sprinkler systems are a common fire protection strategy used in shopping malls, whether there is an atrium or not. Because of the typically high headroom in an atrium, it is often difficult to activate a sprinkler due to a fire at the floor level. Further, flooding the atrium floor with excessive water from a sprinkler can affect evacuation and can cause serious property damage. Sprinkler systems do not satisfy the water conservation criterion for green or sustainable buildings. Alternative systems using less water should be designed for a ‘green or sustainable’ shopping mall with an atrium. The alternative active fire protection systems proposed in this paper are: • Water gun in atrium spaces; • Intelligent fire detection systems in atria; • Water mist fire suppression systems in shops adjacent to an atrium. An atrium in a ‘green or sustainable’ shopping mall is taken as an example. The feasibility of using the above fire protection systems is discussed. The potential advantage of less water use for green or sustainable buildings will be pointed out. Further, designing static smoke exhaust with roof vents for protecting the atrium with minimum use of electric power will be outlined, bearing in mind that a smoke management system is also regarded as an active fire protection system in some countries.

Large eddy simulations for studying tunnel smoke ventilation

Computational fluid dynamics are applied to simulate the smoke movement in a ventilated tunnel fire through large eddy simulation (LES). Several scenarios with different ventilation rates are considered by taking the fire as a volumetric heat source. Results predicted by LES are compared with those from a turbulent kinetic energy; thermal conductivity-dissipation of the turbulent kinetic energy model. These include temperature fields, flame shape and the smoke movement pattern. It is found that thermal stratification and smoke backflow can be predicted successfully by LES. The possibility of applying LES as an engineering tool to smoke management system design in tunnels is discussed. (A) Reprinted with permission from Elsevier.

A new model on simulating smoke transport with computational fluid dynamics

A new model is proposed for simulating smoke movement induced by a fire. Smoke is taken as a collection of particles with size described by a certain distribution function. Movement of the particles will be studied by dividing the physical problem into two parts: solid phase and air phase. The Lagrangian approach is used for studying motion of the solid phase, with the air flow simulated by computational fluid dynamics (CFD). Interaction between the air phase and the solid phase will be described by the particle-source-in-cell method. k– ε types of turbulence models are used in the simulation of air flow. Some of the results are also compared with the fire dynamics simulator model based on large eddy simulation developed at the Building and Fire Research Laboratory, National Institute of Standards and Technology, USA. Application of the model for designing smoke management system is also illustrated. This model should be useful for designing smoke management system as it describes an intermediate step while using CFD.

Possibility of Applying a Performance-based Approach for Designing Means of Escape in a Public Transport Interchange

Performance-based design on building fire safety provisions as an alternative to prescriptive code design is going to be developed in Hong Kong. But how to do this is not yet clear. In this transition period, alternative approach to design for projects with difficulties in complying with prescriptive codes is allowed. Projects would be considered case by case individually. There are always arguments on the design for means of escape (MoE), as the usable floor area will be affected. In this paper, the prescriptive approach of the MoE code with respect to the local buildings characteristics and occupants characteristics are reviewed. Deficiency and inadequacy of the MoE code, which is not yet updated quick enough for getting an appropriate fire safety solution for some building or occupancy types, are discussed. The possibility of adopting performance-based design approach in this transition period is examined. MoE design in a public transport interchange is taken as an example in this paper. Evacuation for the disabled is also discussed. Aspects on designing smoke management system are outlined. The alternative of using drencher system is examined through full-scale burning tests.

Effectiveness of High-Capacity Smoke Exhaust in Large Spaces

Current codes in many countries require that the smoke layer in an atrium or other large space be maintained above the highest means of egress in the space. The smoke exhaust capacity needed to maintain the smoke layer above the highest level of the means of egress can be substantial if that level is near the top of a tall atrium. However, the air entrained along the clear height of the plume that creates the vast quantity of smoke also acts to dilute the smoke. As such, a cost-effective design for an atrium smoke management system may be suggested that causes people to be exposed to the dilute smoke. The adequacy of such a design requires that the qualities of the remaining smoke layer be estimated. A first order analysis to estimate the properties of the smoke layer is described in this paper. Properties of interest include the concentration of gas species, visibility reduction and temperature. In some cases, the visibility may be reduced below 1 m even though the temperature rise and generation of toxic gases are relatively modest. However, with a smoke exhaust rate of 200 kg/s in an atrium, the hazard associated with the smoke layer temperature and CO concentration is modest for a wide range of fuels.

A comprehensive study of externally venting flames —: Part II: Plume envelope and centre-line temperature comparisons, secondary fires, wind effects and smoke management system

In this part, comparisons are presented between predicted and experimental plume characteristics in terms of plume envelope and centre-line temperatures of venting flames during full-scale flashover fires. Window cracking times and heat transfer from the external plume are discussed in relation to the possibility of a secondary fire. Surface and line approximations are developed to represent the change in the external plume temperature with height, width and depth within the plume above the window opening.