Effects of User Dependence on the Prediction Results of Visibility in Fire Simulations

To improve the reliability of safety assessments in domestic performance-based designs (PBDs), the problem of the input parameters being dependent on fire-simulation users was quantitatively analyzed. Thus, the results of statistical analyses of domestic PBD reports evaluated over the last 5 years were examined. It was determined that the uncertainties of the input parameters might have a relatively larger influence on the statistical deviations than the measurement uncertainties. Accordingly, a sensitivity analysis was performed by considering the statistical deviations of the input parameters that could greatly influence the prediction results of visibility, which are important for the available safe egress time. The main results were as follows: a large change in visibility was observed owing to deviations of the heat release rate and soot yield. Based on this study, it is expected that more accurate results can be obtained if the objectivity of input parameters determined by user dependence can be secured in domestic PBDs.

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Heat release rate: The single most important variable in fire hazard

Fire Safety Journal ◽

10.1016/0379-7112(92)90019-9 ◽

1992 ◽

Vol 18 (3) ◽

pp. 255-272 ◽

Cited By ~ 471

Author(s):

Vytenis Babrauskas ◽

Richard D. Peacock

Keyword(s):

Heat Release ◽

Heat Release Rate ◽

Release Rate ◽

Fire Hazard ◽

Important Variable ◽

In Fire

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Adjoint Methods for Elimination of Thermoacoustic Oscillations in a Model Annular Combustor via Small Geometry Modifications

Volume 4A: Combustion, Fuels, and Emissions ◽

10.1115/gt2018-75692 ◽

2018 ◽

Cited By ~ 2

Author(s):

José G. Aguilar ◽

Matthew P. Juniper

Keyword(s):

Sensitivity Analysis ◽

Time Delay ◽

Heat Release ◽

Combustion Chamber ◽

Heat Release Rate ◽

Release Rate ◽

Gas Turbines ◽

Acoustic Pressure ◽

Annular Combustor ◽

Thermoacoustic Oscillations

In gas turbines, thermoacoustic oscillations grow if moments of high fluctuating heat release rate coincide with moments of high acoustic pressure. The phase between the heat release rate and the acoustic pressure depends strongly on the flame behaviour (specifically the time delay) and on the acoustic period. This makes the growth rate of thermoacoustic oscillations exceedingly sensitive to small changes in the acoustic boundary conditions, geometry changes, and the flame time delay. In this paper, adjoint-based sensitivity analysis is applied to a thermoacoustic network model of an annular combustor. This reveals how each eigenvalue is affected by every parameter of the system. This information is combined with an optimization algorithm in order to stabilize all thermoacoustic modes of the combustor by making only small changes to the geometry. The final configuration has a larger plenum area, a smaller premix duct area and a larger combustion chamber volume. All changes are less than 6% of the original values. The technique is readily scalable to more complex models and geometries and the inclusion of further constraints, such that the combustion chamber itself should not change. This demonstrates why adjoint-based sensitivity analysis and optimization could become an indispensible tool for the design of thermoacoustically-stable combustors.

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Defining the Heat Release Rate per Unit Area for Use in Fire Safety Engineering Analysis

Fire Science and Technology 2015 ◽

10.1007/978-981-10-0376-9_42 ◽

2016 ◽

pp. 419-426 ◽

Cited By ~ 1

Author(s):

Charles Fleischmann

Keyword(s):

Heat Release ◽

Heat Release Rate ◽

Release Rate ◽

Fire Safety ◽

Unit Area ◽

Safety Engineering ◽

Engineering Analysis ◽

Fire Safety Engineering ◽

In Fire

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Sensitivity Analysis of FDS Results for the Input Uncertainty of Fire Heat Release Rate

Journal of the Korean Society of Safety ◽

10.14346/jkosos.2016.31.1.025 ◽

2016 ◽

Vol 31 (1) ◽

pp. 25-32 ◽

Cited By ~ 3

Author(s):

Jae-Ho Cho ◽

Cheol-Hong Hwang ◽

Joosung Kim ◽

Sangkyu Lee

Keyword(s):

Sensitivity Analysis ◽

Heat Release ◽

Heat Release Rate ◽

Release Rate ◽

Input Uncertainty

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Use of the mass spectrometer for heat release rate analysis in fire calorimeters

Fire and Materials ◽

10.1002/fam.769 ◽

2001 ◽

Vol 25 (5) ◽

pp. 203-207 ◽

Cited By ~ 3

Author(s):

P.A. (Tony) Enright ◽

Paul Vandevelde

Keyword(s):

Heat Release ◽

Mass Spectrometer ◽

Heat Release Rate ◽

Release Rate ◽

Rate Analysis ◽

In Fire

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Fire Safety Assessment of Epoxy Composites Reinforced by Carbon Fibre and Graphene

Applied Composite Materials ◽

10.1007/s10443-020-09824-4 ◽

2020 ◽

Vol 27 (5) ◽

pp. 619-639 ◽

Cited By ~ 1

Author(s):

Qiangjun Zhang ◽

Yong C Wang ◽

Constantinos Soutis ◽

Colin G. Bailey ◽

Yuan Hu

Keyword(s):

Mechanical Properties ◽

Heat Conduction ◽

Carbon Fibre ◽

Heat Release ◽

Heat Release Rate ◽

Release Rate ◽

Structural Integrity ◽

Composite Panel ◽

Maximum Temperature ◽

In Fire

Abstract This paper presents a coupled numerical investigation to assess the reaction to fire performance and fire resistance of various types of epoxy resin (ER) based composites. It examines the fire response of carbon fibre (CF) reinforced ER (CF/ER), ER with graphene nanoplatelets (GNP/ER) and CF reinforced GNP/ER (CF/GNP/ER). Thermal, physical and pyrolysis properties are presented to assist numerical modelling that is used to assess the material ability to pass the regulatory vertical burn test for new aircraft structures and estimate in-fire and post-fire residual strength properties. Except for the CF/GNP/ER composite, all other material systems fail the vertical burn test due to continuous burning after removal of the fire source. Carbon fibres are non-combustible and therefore reduce heat release rate of the ER composite. By combining this property with the beneficial barrier effects of graphene platelets, the CF/GNP/ER composite with 1.5 wt% GNP and 50 wt% CF self-extinguishes within 15 s after removal of the burner with a relatively small burn length. Graphene drastically slows down heat conduction and migration of decomposed volatiles to the surface by creating improved char structures. Thus, graphene is allowing the CF/GNP/ER composite panel to pass the regulatory vertical burn test. Due to low heat conduction and reduced heat release rate, the maximum temperatures in the CF/GNP/ER composite are low so the composite material retains very high in-fire and post-fire mechanical properties, maintaining structural integrity. In contrast, temperatures in the CF/ER composite are much higher. At a maximum temperature of 86 °C, the residual in-fire tensile and compressive mechanical strengths of CF/GNP/ER are about 87% and 59% respectively of the ambient temperature values, compared to 70% and 21% respectively for the CF/ER composite that has a temperature of 140 °C at the same time (but the CF/ER temperature will be higher due to continuing burning). Converting mass losses of the composites into char depth, the post-fire mechanical properties of the CF/GNP/ER composite are about 75% of the ambient condition compared to about 68% for the CF/ER composite.

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Fire Performance of Nylon Nanocomposites Fabricated by Melt Intercalation

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.334-335.737 ◽

2007 ◽

Vol 334-335 ◽

pp. 737-740

Author(s):

Russel J. Varley ◽

Andrew M. Groth ◽

Kok Hoong Leong

Keyword(s):

Heat Release ◽

Heat Release Rate ◽

Release Rate ◽

Fire Performance ◽

Fire Retardancy ◽

Cone Calorimetry ◽

Char Layer ◽

Transmission Electron ◽

Peak Heat Release Rate ◽

In Fire

This paper presents results of a study carried out to evaluate the effects of an organomodified nanoclay, either on its own or in combination with a polyimide, upon the fire performance of a commercially available nylon. The fire performance, as determined using cone calorimetry showed that up to 40% improvement in the peak heat release rate could be achieved at addition levels of only around 5wt% of nanoclay. The level of improvement was shown to be strongly dependent upon nanoscale dispersion with a more highly exfoliated morphology, as determined using transmission electron microscopy, which showed a greater reduction in the peak heat release rate compared to a more ordered intercalated structure. Investigation of the mechanism of fire retardancy showed that the reduction in the heat release rate is due to the nanoclay reinforcing the char layer which prevented combustible products from entering in to the gaseous phase. Generally, though, the time to ignition is unaffected by nanoclay additions. The addition of the polyimide to the nanoclay reinforced nylon was inconclusive showing little evidence of further improvements in fire performance.

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Analysis of Zone Fire Models and their Application in Structural Fire Design

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.322.127 ◽

2021 ◽

Vol 322 ◽

pp. 127-135

Author(s):

Nicole Svobodová ◽

Martin Benýšek ◽

Radek Štefan

Keyword(s):

Heat Release ◽

Heat Release Rate ◽

Release Rate ◽

Concrete Slab ◽

Software Tools ◽

Structural Fire ◽

Fire Models ◽

Fire Modelling ◽

Input Parameters ◽

Fire Design

This paper is focused on a comparison of zone fire modelling software tools and their application in structural fire design. The analysis of the zone models is performed for five selected computer programs, namely Argos, Branzfire, B-RISK, CFAST, and OZone. The limits and input parameters ofthe zone fire modelling software tools are described. In each software, two variants of the analysed compartment are created for simulating two types of fire scenario, including the fuel-controlled fire and the ventilation-controlled fire. The burning regimes are defined based on two heat release rate(HRR) curves, determined according to EN 1991-1-2. The HRR curves parameters are used as the main input data into the fire modelling software. The fire simulation method in each fire modelling software is selected based on the software capabilities. Although each program requires a different amount of input parameters, the aim was to create the same model in all programs and to compare the results. The fire modelling software outputs are exported into a spreadsheet. Subsequently, a comparison of the resulting graphs is performed, particularly the heat release rate graphs and the upper layertemperature evolution graphs. The fire resistance assessment of a simply-supported concrete slab panel is performed for all zone fire models and then the results are compared. The fire modelling software tools are finally quantitatively and qualitatively evaluated and compared to assess their differences.

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