Parallel Computation of Smoke Movement During a Car Park Fire

In this paper the use of Fire Dynamics Simulator (FDS) for parallel computer simulation of the smoke movement during a fire of two passenger cars in an underground car park is investigated. The simulations were executed on a high-performance computer cluster. A specific problem of FDS parallel computation using Message-Passing Interface (MPI) is a separate solution of governing equations on computational subdomains causing a loss of accuracy. Therefore, the impact of parallelisation on simulation accuracy in the case of using a greater number of computational cores of the computer cluster is studied with the aim to increase the computational performance and enable practical application of such simulations for fire safety measures. The geometrical model and material properties of the cars used in the simulation have been verified by a full-scale fire experiment in open air. We describe the results of a series of simulations of several fire scenarios with different numbers of parked cars and ventilation configurations and determine times and locations at which conditions in the car park become untenable for human life. The simulation indicates that proper ventilation prolongs tenable conditions by several minutes

Predicting Smoke Detector Responce Using a Quantitative Salt-Water Modeling Technique

This investigation provides a detailed analysis of the hydraulic analogue technique used as a predictive tool for understanding smoke detector response within a complex enclosure. There currently exists no collectively accepted method for predicting the response of smoke detectors; one of the most important elements in life safety. A quantitative technique has been developed using salt-water modeling and planar laser induced fluorescence (PLIF) diagnostics. The non-intrusive diagnostic technique is used to temporally and spatially characterize the dispersion of a buoyant plume within a 1/7th scale room-corridor-room enclosure. This configuration is geometrically similar to a full-scale fire test facility, where local conditions were characterized near five ionization type smoke detectors placed throughout the enclosure. An evaluation of the scaled local conditions and dispersive event times for both systems was used to formulate a preliminary predictive detector response model for use with the hydraulic analogue

Classification of critical levels of CO exposure of firefigthers through monitored heart rate

Smoke inhalation poses a serious health threat to firefighters (FFs), with potential effects including respiratory and cardiac disorders. In this work, environmental and physiological data were collected from FFs, during experimental fires performed in 2015 and 2019. Extending a previous work, which allowed us to conclude that changes in heart rate (HR) were associated with alterations in the inhalation of carbon monoxide (CO), we performed a HR analysis according to different levels of CO exposure during firefighting based on data collected from three FFs. Based on HR collected and on CO occupational exposure standards (OES), we propose a classifier to identify CO exposure levels through the HR measured values. An ensemble of 100 bagged classification trees was used and the classification of CO levels obtained an overall accuracy of 91.9%. The classification can be performed in real-time and can be embedded in a decision fire-fighting support system. This classification of FF’ exposure to critical CO levels, through minimally-invasive monitored HR, opens the possibility to identify hazardous situations, preventing and avoiding possible severe problems in FF’ health due to inhaled pollutants. The obtained results also show the importance of future studies on the relevance and influence of the exposure and inhalation of pollutants on the FF’ health, especially in what refers to hazardous levels of toxic air pollutants.publishe

Numerical Simulations of Small-scale and Full-scale Fire Experiments

A fundamental part of fire safety engineering is dedicated to the application of numerical fire models. Accurate predictions of real-life fires are needed in scenarios related to fire growth, smoke propagation, occupant egress, and structural integrity. In the context of building safety, fire modelling tools can be used to predict the response of materials to fire situations, and are increasingly prevalent in performance based design. In the present work, heat transfer and fire simulations are created with the objective to predict the resultant fire effects of different experiments. The simulations range in complexity from algebraic finite difference models to computational fluid dynamics (CFD) calculations. For each set of simulations, numerical predictions are compared with experimental data, whenever available. FireFOAM, an open source computational fluid dynamics solver, is selected as the modelling tool of choice. In the present study, four sets of simulations are conducted based upon experimental work. Firstly, a small scale test apparatus, the cone calorimeter, is investigated. Predictions from both a finite difference model and a CFD model compare favourably to the experimental results, and it is confirmed that a 1D finite difference model is not appropriate for the experimental configuration. Secondly, a full-scale fire experiment is investigated. The CFD simulations are extended to include the effects of turbulence and combustion. Large Eddy Simulation (LES) is selected for the turbulence modelling with a one equation eddy-viscosity model. Infinitely fast chemistry is assumed, and the eddy dissipation concept (EDC) is employed where combustion is controlled by the rate of turbulent mixing. Thirdly, a two-step reaction mechanism is implemented to account for compartment fires with under-ventilated combustion and more complex fuels. Chemistry based upon Arrhenius rate constants is assumed, and the Partially Stirred Reactor (PaSR) approach is employed. Good agreement is found for species and temperature predictions, with over-prediction of carbon dioxide concentrations due to modelling the reaction rates too fast. Finally, a preliminary CFD study is carried out for a multi-compartment fire where a wall section separates two compartments. Heat transfer is found to be over-predicted through the non-degrading wall section. To enhance the capabilities of the simulations, pyrolysis is recommended to be implemented to enable modelling of representative wall sections and realistic fuel loads

Parallel Computer Simulation of Fire in Road Tunnel and People Evacuation

Advances in CFD (Computational Fluid Dynamics) and significant increase of computational power of current computers have led to widespread use of CFD in aerodynamics, fluid dynamics, combustion engineering and other academic disciplines. One of such disciplines is computer modelling and simulation of fire in human structures. Fire is a very complicated and complex phenomenon. Fire research deals with such processes as combustion, radiation, heat transfer, turbulence, fluid dynamics, and other physical and chemical processes. Several advanced fire and smoke simulation systems have been developed to solve various aspects of fire safety in various conditions and environments. In this paper, the use of parallel version of the CFD simulator FDS (Fire Dynamics Simulator) for the simulation of fire spread and smoke development in a short road tunnel is described. In order to study the impact of the computational domain decomposition on the accuracy and reliability of simulation results, several simulations of a chosen fire scenario ran on the HP blade cluster utilizing different numbers of processors. The obtained parameters of fire and smoke were used to investigate the influence of the fire on people evacuation in the tunnel with active ventilation for a given traffic situation

Influence of natural smoke vent opening in stairway of multistorey building

Stairway used as an escape as well as firefighter's route during evacuation. In addition, stairway connecting different floors of a building and becomes a path for the smoke spread in fire event. In a building, every escape route should be installed with smoke control system to ensure the prevention of dangerous smoke accumulation at those areas. The fire perimeter in terms of heat output and smoke generation is highly depends on building occupancy and the efficacy of smoke confinement may have a great challenge. In this paper, numerical simulations were conducted to study the efficacy of natural smoke vent to confine fire-induced smoke transportation in the stairways of multi-storeys buildings. The simulation used Fire Dynamic Simulator (FDS) was conducted on a full-scale building where the influences of smoke vent opening at different fire size were discussed. When the value of heat release rate (HRR) were kept constant, the different vent's size opening had a different influence on the efficacy of smoke vent and an appropriate opening size was obtained and proposed for further action. The finding of this study can assist the fire engineer to ensure that the smoke vent installation play a good role in confinement of smoke diffusion