The acceleration of flames in tube explosions with two obstacles as a function of the obstacle separation distance

Na’inna, Abdulmajid M.; Phylaktou, Herodotos N.; Andrews, Gordon E.

doi:10.1016/j.jlp.2013.08.003

Cited by 60 publications

(13 citation statements)

References 14 publications

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“…8 lie close to the line with C = 4 in Eq. 6 [33], but the previous results of Na'inna et al with two interacting grid plates with 30% BR [17,18] were closer to C = 2 at the higher u'/SL of this work. ST/SL ratios of 55 to 120 were found for two interacting bar type grid plates with a BR of 20%.…”

Section: Turbulent Burning Velocity As a Function Of The Predicted Pecontrasting

confidence: 56%

“…The spacing between the double obstacles was systematically varied from 0.5 m to 2.75 m. A clear effect of obstacle separation distance on gas explosion severity (flame speed and overpressure) was established with an obstacle separation of 1.75 m which produced close to 300 kPa overpressure and a flame speed of 500 m/s. These values were higher by a factor of two when compared to the overpressure and flame speed with an obstacle separation distance of 2.75 m. Na'inna et al [17] also showed that there is an agreement between the dependence of maximum explosion severity on the separation distance and turbulence profile determined in cold flow by other researchers. Nonetheless, the results showed that the peak acceleration of the flame emerged further downstream of the obstacle than the position of maximum turbulence determined in the cold flow studies.…”

Section: Introductionmentioning

confidence: 67%

“…Also included in Fig. 8 are the previous results of Na'inna et al [17,18] for orifice plate circular hole grid plates of 30% BR with varying separation distance and for different mixture reactivities. Figure 8 also includes the data range from the review of turbulent to laminar burning velocity ratio of Phylaktou et al [32,33], which extends to ST/SL of 120.…”

Section: Turbulent Burning Velocity As a Function Of The Predicted Pementioning

confidence: 99%

“…Na'inna et al [17] reported an experimental study in an elongated tube with two orifice plate obstacles of 30% BR each and 10% methane/air as explosible mixture. The spacing between the double obstacles was systematically varied from 0.5 m to 2.75 m. A clear effect of obstacle separation distance on gas explosion severity (flame speed and overpressure) was established with an obstacle separation of 1.75 m which produced close to 300 kPa overpressure and a flame speed of 500 m/s.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Explosion flame acceleration over obstacles: Effects of separation distance for a range of scales

Na’inna

Phylaktou

Andrews

2017

Process Safety and Environmental Protection

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Section: Turbulent Burning Velocity As a Function Of The Predicted Pecontrasting

confidence: 56%

Section: Introductionmentioning

confidence: 67%

Section: Turbulent Burning Velocity As a Function Of The Predicted Pementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Explosion flame acceleration over obstacles: Effects of separation distance for a range of scales

Na’inna

Phylaktou

Andrews

2017

Process Safety and Environmental Protection

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“…Previous studies have shown that reducing the vent size and increasing congestion, in the form of obstacles in the path of the propagating flame front, can affect flame speeds and result in increased overpressures in vented explosions Bauwens et al, 2010;Bimson et al, 1993;Chan et al, 1983;Fakandu et al, 2013;Hall, Masri, Yaroshchyk, & Ibrahim, 2009;Mercx et al, 1993;Na'inna, Phylaktou, & Andrews, 2013a, 2013bPappas, 1983;Park, Lee, & Green, 2008;Phylaktou & Andrews, 1994;Phylaktou, 1993;Pritchard, Hedley, & Webber, 2002;Solberg, Pappas, & Skramstad, 1980;Taylor & Bimson, 1989;van Wingerden, 1984avan Wingerden, , 1984cvan Wingerden, 1989;van Wingerden & Zeeuwen, 1983a, 1983cZalosh, 1980Zalosh, , 2008.…”

Section: Introductionmentioning

confidence: 99%

The effect of vent size and congestion in large-scale vented natural gas/air explosions

Tomlin

Johnson

Cronin

et al. 2015

Journal of Loss Prevention in the Process Industries

103

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A typical building consists of a number of rooms; often with windows of different size and failure pressure and obstructions in the form of furniture and décor, separated by partition walls with interconnecting doorways. Consequently, the maximum pressure developed in a gas explosion would be dependent upon the individual characteristics of the building. In this research, a large-scale experimental programme has been undertaken at the DNV GL Spadeadam Test Site to determine the effects of vent size and congestion on vented gas explosions. Thirtyeight stoichiometric natural gas/air explosions were carried out in a 182 m 3 explosion chamber of L/D = 2 and K A = 1, 2, 4 and 9. Congestion was varied by placing a number of 180 mm diameter polyethylene pipes within the explosion chamber, providing a volume congestion between 0 and 5% and cross-sectional area blockages ranging between 0 and 40%. The series of tests produced peak explosion overpressures of between 70 mbar and 3.7 bar with corresponding maximum flame speeds in the range 35 -395 m/s at a distance of 7 m from the ignition point. The experiments demonstrated that it is possible to generate overpressures greater than 200 mbar with volume blockages of as little as 0.57%, if there is not sufficient outflow through the inadvertent venting process. The size and failure pressure of potential vent openings, and the degree of congestion within a building, are key factors in whether or not a building will sustain structural damage following a gas explosion. Given that the average volume blockage in a room in a UK inhabited building is in the order of 17%, it is clear that without the use of large windows of low failure pressure, buildings will continue to be susceptible to significant structural damage during an accidental gas explosion.

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The effect of an obstacle on methane-air explosions in a spherical vessel connected to a pipeline

et al. 2016

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A series of experiments are carried out to reveal the effect of an obstacle on the explosion intensity of a methane‐air mixture in a spherical vessel connected to a pipeline. Results show that obstacle presence, blockage ratio, and position play significant roles in explosion intensity. The oscillation amplitude of pressure both in the vessel and at the pipeline terminus weakens when an obstacle exists in the pipeline. The effects of the blockage ratio on explosion intensity are different when obstacle position changes. Explosive intensity decreases with blockage ratio when the obstacle is set at the intersection of the spherical vessel and the pipeline and in the middle section of the pipeline. Moreover, when the blockage ratio is ∼56%, the minimum explosion intensity is obtained when the obstacle is set at the middle section of the pipeline. Explosion intensity increases with blockage ratio when the obstacle is positioned near the pipeline terminus. The most dangerous case is when the obstacle is positioned near the pipeline terminus, especially when the blockage ratio is 75% or greater. The maximum pressure and the rate of pressure increase at the point of intersection of the spherical vessel and the pipeline are higher than at the middle section. The conclusions provide an important reference for designing explosion venting safety systems and explosion‐resistant designs. © 2016 American Institute of Chemical Engineers Process Saf Prog 36: 67–73, 2017

show abstract

The acceleration of flames in tube explosions with two obstacles as a function of the obstacle separation distance

Cited by 60 publications

References 14 publications

Explosion flame acceleration over obstacles: Effects of separation distance for a range of scales

Explosion flame acceleration over obstacles: Effects of separation distance for a range of scales

The effect of vent size and congestion in large-scale vented natural gas/air explosions

The effect of an obstacle on methane-air explosions in a spherical vessel connected to a pipeline

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