Experimental and numerical study of low frequency oscillatory behaviour of a large-scale hydrocarbon pool fire in a mechanically ventilated compartment

Prétrel, Hugues; Suard, Sylvain; Audouin, L.

doi:10.1016/j.firesaf.2016.04.001

Cited by 37 publications

(23 citation statements)

References 21 publications

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“…Secondly, the frequency increases with the ARR, in average from 16 to 26 mHz (corresponding to periods from 38 to 63 s). This trend is similar to the one observed in large-scale experiments by Prétrel et al (2016).…”

Section: Influence Of Renewal Ratesupporting

confidence: 90%

“…For fires in enclosures equipped with mechanical ventilation, such as in nuclear facilities, low-frequency oscillatory behavior can be encountered, leading to large pressure variations that can affect the confinement levels and hence the safety of the installation. This LF oscillatory behavior was observed by Audouin et al (2013) and Prétrel et al (2016) from experiments on heptane pool fires in the large-scale DIVA facility of IRSN (Institut de Radioprotection et de Sûreté Nucléaire). They reported frequencies in the range of 5-7 mHz for 0.5-MW heptane pool fires and air renewal rates between 12 and 17 h -1 .…”

Section: Introductionsupporting

confidence: 53%

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Experimental study on low-frequency oscillating behavior in mechanically-ventilated compartment fires

Mense¹,

Pizzo

Pretrel³

et al. 2019

JAFM

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This study focuses on fire behavior in a mechanically-ventilated compartment, with a special emphasis on the low-frequency (LF) oscillatory behavior that has been occasionally observed. LF oscillations, typically in the order of a few mHz, can lead to large thermodynamic pressure variations, which in turn can cause fire safety issues (e.g. loss of confinement, mechanical damages). To address these issues, small-scale experiments are conducted varying the air renewal rate (ARR) in the compartment from 8 to 20 h-1 and the ventilation configuration. The fire source consists of heptane fuel loaded in a pan with a diameter of 18 cm. Depending on the ARR, LF oscillations are observed on the time evolution of the burning rate, and thus of all the other variables, with a frequency in the range of 16-26 mHz. As the ARR increases, there are three distinct regimes of burning behavior observed in this study: (1) rapid extinction due to smoke filling; (2) LF oscillating burning, followed by blow-off extinction after a few oscillations; and (3) LF oscillating burning, where extinction occurs because of the burning rate "runaway" due to an intensification of the heat transfer through the rim of the container. The oscillatory behavior and fire extinction result from the competition between oxygen supply and fuel vapor supply due to the heat feedback to the fuel tray. Both regimes (2) and (3) are accompanied by displacements of the flame out of the pan towards regions where oxygen is present. The influence of ARR and ventilation configuration (i.e. air inlet location and blowing direction) on the burning rate and LF oscillation properties (frequency, amplitude) is examined and discussed.

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Section: Influence Of Renewal Ratesupporting

confidence: 90%

Section: Introductionsupporting

confidence: 53%

Experimental study on low-frequency oscillating behavior in mechanically-ventilated compartment fires

Mense¹,

Pizzo

Pretrel³

et al. 2019

JAFM

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“…For the PR2_VSP_3 test for which conditions are close to the extinction limit, three large oscillations of the burning rate are observed with an average frequency of 6.7 10 −3 Hz (average period of 148 seconds) and large amplitude of about 20 g/s for an average value of 14.8 g/s. These are typical to low frequency behavior and very similar to fire oscillations encountered in one forced‐ventilated room without vent . They are explained as a coupling between the burning rate, the pressure in the room that governs the oxygen entrance, and the convective time for the oxygen to reach the burning area.…”

Section: Analysis Of the Testsupporting

confidence: 53%

“…These are typical to low frequency behavior and very similar to fire oscillations encountered in one forced-ventilated room without vent. 27 They are explained as a coupling between the burning rate, the pressure in the room that governs the oxygen entrance, and the convective time for the oxygen to reach the burning area. This oscillatory behavior can also be related to several recent studies showing the occurrence of oscillatory fire and ghosting flame phenomena with vent in naturally ventilated room, without mechanical ventilation.…”

Section: Analysis Of the Burning Ratementioning

confidence: 99%

Experimental and numerical analysis of fire scenarios involving two mechanically ventilated compartments connected together with a horizontal vent

Prétrel

Vaux

2019

Fire and Materials

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Summary This work deals with an experimental and numerical investigation of a fire scenario involving two rooms mechanically ventilated and connected together with a horizontal vent. The objective is to improve the understanding of the physical phenomena and to assess the capability of computational fluid dynamics (CFD) numerical simulations to predict flow field for such a fire scenario. The study is based on a set of large‐scale fire experiments performed in the framework of the OECD PRISME‐2 project in the DIVA multi‐room facility of the Institut de Radioprotection et de Sûreté Nucléaire (IRSN) and of numerical simulations performed with the ISIS CFD code. The fire scenario consists of two rooms, one above the other, mechanically ventilated and connected to each other with a horizontal vent of 1 m2. The fire is a heptane pool fire located in the lower room. The analysis focuses on the coupling between the burning rate, the flow at the vent, and the configuration of the mechanical ventilation. Several regimes of combustion are encountered from well‐ventilated steady fire to under‐ventilated unsteady and oscillatory fire. The results show that the burning rate is controlled by both the mechanical ventilation and the downward flow from the vent. The numerical simulations highlight the specific pattern of the oxygen concentration field induced by the downward flow at the vent.

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“…In addition to the large scale fire tests, extra support tests for the characterization of fire sources, in open atmosphere, were performed to provide additional data for validation purposes. As in the previous PRISME project, the analytical working group evaluated the capabilities of various fire modelling codes to simulate fire scenarios based on the PRISME 2 results . The output of the PRISME 2 project has been summarized in the OECD/NEA application report…”

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confidence: 99%

Fire development in multi‐compartment facilities: PRISME 2 project

et al. 2019

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Experimental and numerical study of low frequency oscillatory behaviour of a large-scale hydrocarbon pool fire in a mechanically ventilated compartment

Cited by 37 publications

References 21 publications

Experimental study on low-frequency oscillating behavior in mechanically-ventilated compartment fires

Experimental study on low-frequency oscillating behavior in mechanically-ventilated compartment fires

Experimental and numerical analysis of fire scenarios involving two mechanically ventilated compartments connected together with a horizontal vent

Fire development in multi‐compartment facilities: PRISME 2 project

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