1. Compartment fire dynamics in taller timber buildings : guidance for performance-based fire safety engineeringIan Pope, Antonela Čolić, Chamith Karannagodage, Ahmed Ahmed Ali Awadallah, Andrea Lucherini, 2025, samostojni znanstveni sestavek ali poglavje v monografski publikaciji Povzetek: In comparison to non-combustible construction materials commonly used for taller buildings, timber elements can significantly alter the fire dynamics in a compartment. This fundamentally challenges many of the conventional fire safety strategies and design approaches for mid-rise and high-rise buildings. Consequently, many building industry practitioners are questioning the limitations of existing methodologies, while searching for additional ways to account for this different fire behaviour in the design, construction, and operation of timber buildings. In seeking to address these questions, this chapter describes the state-of-the-art and recent advances in understanding the fire behaviour in compartments with areas of exposed timber (e.g., engineered wood products), and protected timber elements that may contribute to the fire if their encapsulation fails. Relevant experimental findings and engineering approaches to date are summarised and discussed, and design guidance is provided in relation to the typical phases of realistic or ‘natural’ fires, namely the growth phase, the fully-developed phase, the fire decay, and the cooling phase. Critical fire phenomena and their impacts on the fire safety strategy are addressed, such as fire spread; active fire suppression; heat induced delamination and char fall-off; and self-extinguishment.
Ključne besede: timber, fire dynamics, fire safety, self-extinguishment, heat induced delamination, char fall-off
Objavljeno v DiRROS: 18.11.2025; Ogledov: 212; Prenosov: 83
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2. Predicting the total wall time of CFD simulations of single-compartment firesMartin Veit, Andrea Lucherini, Georgios Maragkos, Bart Merci, 2024, objavljeni znanstveni prispevek na konferenci Povzetek: The total wall time is often difficult to predict a priori in compartment fire simulations due to dynamic phenomena that can occur, e.g., flame extinction. The wall time is dependent on multiple physical factors in the simulation, along with simulation factors and the system used to compute the model. Specifically, the CFL number of a simulation is highly influential to the wall time, as this restricts the time step size. In this paper, the prediction of the total wall time for a single-compartment fire is investigated considering varying fire heat release rates and compartment ventilation factors. It is shown that an increasing heat release rate increases the total wall time due to higher velocities inside the compartment. Furthermore, when the compartment becomes under-ventilated, the wall time becomes more difficult to predict early on in the simulation, as steady state conditions are reached later, compared to well-ventilated cases. The time at which the wall time can be accurately predicted changed from a few physical seconds in the well-ventilated case, to up to 60 physical seconds for the under-ventilated case.
Ključne besede: simulations, computational fluid dynamics, fire dynamics simulator, wall time
Objavljeno v DiRROS: 19.12.2024; Ogledov: 685; Prenosov: 369
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3. CFD-based analysis of deviations between thermocouple measurements and local gas temperatures during the cooling phase of compartment firesFlorian Put, Andrea Lucherini, Ruben Van Coile, Bart Merci, 2024, izvirni znanstveni članek Povzetek: Data from thermocouple (TC) measurements play a pivotal role in fire safety science and engineering studies. It is well-known that there are deviations from the actual local gas temperature and many studies have led to the development of correction factors. The present study focuses on these deviations inside compartments through a systematic series of CFD simulations, performed with Fire Dynamics Simulator (FDS), version 6.8.0. A canonical cubic box is used as geometry. This allows for the demonstration of the impact of the presence of smoke, with variable optical thickness, on the TC data as retrieved from FDS. Significant differences are observed between TC measurements and local gas temperatures. Corrections as developed for TC measurements in open atmospheres cannot be readily applied in compartment configurations, where smoke properties change both spatially and temporally.
Ključne besede: thermocouple measurements, CFD simulations, heat transfer, compartment fires, cooling, fire dynamics, FDS
Objavljeno v DiRROS: 28.10.2024; Ogledov: 838; Prenosov: 330
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4. Thermal characterisation of the cooling phase of post-flashover compartment firesAndrea Lucherini, Balša Jovanović, Jose L. Torero, Ruben Van Coile, Bart Merci, 2024, izvirni znanstveni članek Povzetek: The main characteristics of the cooling phase of post-flashover compartment fires are studied using a simplified first-principles heat transfer approach to establish key limitations of more traditional methodologies (e.g., Eurocode). To this purpose, the boundary conditions during cooling are analysed. To illustrate the importance of a first-principles approach, a detailed review of the literature is presented followed by the presentation of a simplified numerical model. The model is constructed to calculate first-order thermal conditions during the cooling phase. The model is not intended to provide a precise calculation method but rather baseline estimates that incorporate all key thermal inputs and outputs. First, the thermal boundary conditions in the heating phase are approximated with a single (gas) temperature and the Eurocode parametric fire curves, to provide a consistent initial condition for the cooling phase and to be able to compare the traditional approach to the first- principles approach. After fuel burnout, the compartment gases become optically thin and temperatures decay to ambient values, while the compartment solid elements slowly cool down. For simplicity, convective cooling of the compartment linings is estimated using a constant convective heat transfer coefficient and all linings surfaces are assumed to have the same temperature (no net radiative heat exchange). All structural elements are assumed to be thermally thick. While these simplifications introduce quantitative errors, they enable an analytical solution for transient heat conduction in a semi-infinite solid that captures all key heat transfer processes. Comparisons between the results obtained using both approaches highlight how, even when considering the same fire energy input, the thermal boundary conditions according to the Eurocode parametric fire curves lead to an increase energy accumulated in the solid after fuel burnout and a delay in the onset of cooling. This is not physically correct, and it may lead to misrepresentation of the impact of post-flashover fires on structural behaviour.
Ključne besede: cooling phase, fire decay, fire dynamics, compartment fires, structural fire engineering, fire safety
Objavljeno v DiRROS: 15.04.2024; Ogledov: 1492; Prenosov: 731
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5. Defining the fire decay and the cooling phase of post-flashover compartment firesAndrea Lucherini, Jose L. Torero, 2023, izvirni znanstveni članek Povzetek: The current research study discusses and characterises the fire decay and cooling phase of post-flashover compartment fires, as they are often mixed up despite their important heat transfer differences. The two pha- ses are defined according to the fire heat release rate time-history. The fire decay represents the phase in which the fire heat release rate decreases from the ventilation- or fuel-limited steady-state value of the fully-developed phase to fire extinguishment. This phase is highly influenced by the fuel characteristics, ranging from fast decays for hydrocarbon and liquid fuels to slow decays for charring cellulosic fuels (wood). Once the fuel is consumed, the compartment volume enters the cooling phase, where the cooling in the gas-phase and solid-phase happens with significantly different modes and characteristic times. The thermal boundary conditions at the structural elements are then defined according to physical characteristics and dynamics within the compartment. The research study also underlines how the existing performance-based methodologies lack explicit definitions of the decay and cooling phases and the corresponding thermal boundary conditions for the design of fire-safe struc- tural elements under realistic fire conditions.
Ključne besede: razpadanje ognja, hlajenje, izgorevanje, naravna izpostavljenost ognju, dinamika požara, požari v oddelkih, požarno inženirstvo, učinkovitost, požarna varnost, fire decay, cooling, burnout, natural fire exposure, fire dynamics, compartment fires, structural fire engineering, performance-based, fire safety
Objavljeno v DiRROS: 13.11.2023; Ogledov: 1741; Prenosov: 825
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6. Experimental study of the fire dynamics in a semi-enclosure formed by photovoltaic (PV) installations on flat roof constructionsJens Steemann Kristensen, Benjamin Jacobs, Grunde Jomaas, 2022, izvirni znanstveni članek Povzetek: Flame spread experiments upon a BROOF(t4) compliant flat roof mock-up located below a vertical barrier were carried out for variations in gap height, inclination, subjacent insulation material, and the barrier type (stainless-steel board or photovoltaic (PV) module). A binary flame spread scenario was identified, where re-radiation from the flame facilitated self-sustained flame spread if the gap height to the horizontal panel was below 10 cm for the stainless-steel board and 11 cm for PV modules. These were defined as the critical gap heights. Inclination of the PV modules increased the critical gap height and caused a 25% faster flame spread rate (FSR) than the FSR below horizontal modules with the same gap height at the location of ignition. The faster FSR for inclined modules caused a 40% reduction of the maximum temperature measured at a depth of 70 mm in the insulation materials (242°C). Based on temperatures measured in the insulation materials, the 60 mm polyisocyanurate (PIR) insulation performed slightly better than the 50 mm mineral wool insulation. However, it is expected that the mineral wool would outperform the PIR insulation if tested with the same thickness, as it insulates significantly better at high temperatures. Finally, no sustained flame spread was observed on the back side polymer sheet of the PV modules, but one of the three PV module brands produced burning droplets. Based on the experiments, it can be concluded that the current standards are inadequate as the introduction of a PV system on a compliant roof construction enables flame spread.
Ključne besede: photovoltaic (PV) installations, flame spread, fire dynamics, property protection, open access
Objavljeno v DiRROS: 31.05.2023; Ogledov: 1433; Prenosov: 1158
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