Effect of bifurcation on premixed methane-air explosion overpressure in pipes

Lin, Baiquan; Guo, Chunhui; Sun, Youhong; Zhu, Chuanjie; Hong, Youshi; Yao, Hao

doi:10.1016/j.jlp.2016.07.011

“…The propagation of gas explosion in different pipeline structures or with different obstacles has been studied extensively through experiments and numerical simulations [8][9][10][11]. Lin et al [12][13][14][15] conducted a series of studies on the influence of obstacles, bifurcated pipes, single bend, U-shaped pipe and Z-shaped pipe, and T-shaped pipes in confined spaces on the shock wave and flame wave of a gas explosion. Yu et al [16][17][18][19] studied the influences of the number, size, shape, and position of obstacles on the propagation of a blast wave by means of experiments and numerical simulations.…”

Section: Introductionmentioning

confidence: 99%

Effect of Different Bend Pipes on the Propagation Characteristics of Premixed Methane-Air Explosion in Confined Spaces

Jinwei

¹

,

Jiang

²

,

Tang

³

et al. 2021

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To explore the effect of different bend pipes on the propagation characteristics of premixed methane-air explosion, the experimental explosion pipe system and numerical model were established. By adopting the comparative analysis of experiments and numerical modeling, it conducted researches on the overpressure evolution of gas explosion shock wave in pipes with different bends and obtained the expressions of attenuation coefficient of shock wave overpressure. The results showed that the change of pipe direction accelerated the attenuation of gas explosion shock wave. The propagation attenuation of gas explosion in the bend pipe was mainly affected by the bending angle and initial peak overpressure before bending. With the increase of the bending angle, the attenuation coefficient of gas explosion shock wave gradually increased. For the same bending angle, the attenuation coefficient of gas explosion shock wave increased with the increase of gas volume. The obtained coupling relationships between attenuation coefficient, bending angle, and initial peak overpressure before bending were useful for estimating the overpressure value after the bend. The results presented in this paper have important significance for the assessment of structures that have been damaged in the mine laneway of gas exploration accidents, further enriching the gas exploration spread theory.

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“…e results demonstrated that maximum overpressure, density, temperature, gas velocity, explosion-proof distance, and combustion rate decrease with the increase of the equivalent pipe diameter. Lin et al [28] conducted an experiment on the effect of premixed methane-air explosion overpressure by using three different types of bifurcation pipe; the result showed that the peak overpressure had a downtrend before the bifurcation, a sharp increase after the bifurcation until the maximum was reached, and a downtrend at the pipe end.…”

Section: Introductionmentioning

confidence: 99%

Influence of Cavity Width on Attenuation Characteristic of Gas Explosion Wave

Xu

¹

,

Mu

²

,

Li

³

et al. 2021

Shock and Vibration

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This study aimed to investigate the influence of cavity width on the attenuation characteristic of gas explosion wave. Attenuation mechanism of gas explosion wave through cavity was obtained by numerical simulation. The gas explosion shock wave energy can be greatly attenuated through the cavity structure in five stages, namely, plane wave, expansion, oblique reflection, Mach reflection, and reflection stack, to ensure that it is eliminated. Cavities with various width sizes, namely, 500 ∗ 300 ∗ 200, 500 ∗ 500 ∗ 200, and 500 ∗ 800 ∗ 200 (length ∗ width ∗ height, unit: mm), were experimented to further investigate the attenuation characteristics through a self-established large-size pipe gas explosion experimental system with 200 mm diameter and 36 m length. Results showed an evident attenuation effect on flame duration light intensity (FDLI) and peak overpressure with increasing cavity width. Compared with 300 mm, the overall FDLI decreased by 83.0%, and the peak overpressure decreased by 71.2% when the cavity width was 800 mm. The fitting curves of the FDLI and peak overpressure attenuation factors to width-diameter demonstrated that the critical width-diameter was 2.19 when the FDLI attenuation factor was 1. The FDLI attenuation factor sharply decreased at the width-diameter ratio range from 1.5 to 2.5 and basically remained steady at 0.17 at the width-diameter ratio range from 2.7 to 4.0. The peak overpressure attenuation factor gradually decreased with the increase of width-diameter ratio and changed from 0.93 to 0.28 with width-diameter ratio from 1.5 to 4.0. The research results can serve as a good reference for the design of gas explosion wave-absorbing structures.

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“…Wen [6] studied that the overpressure value generated when the angle of 90° between the obstacles and the inner wall of the pipeline is the largest in the same obstacle length with different obstacles angles. For the obstacles with the same angle, the larger the blocking rate, the lower the maximum flame speed Lin [7] experimentally researched on the effect of different bifurcation angles on premixed methane air explosion overpressure in pipes, the peak overpressure evolution in pipes exhibited a downward trend before the bifurcation, a sharp increase after the bifurcation until reaching the maximum, and it also found that gas explosion propagation was affected by the joint action of turbulence induced by obstacles and the abrupt increase of the cross-sectional area. Kim [8] studied the flame behavior and blast waves during unconfined hydrogen deflagrations.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Effect of Air Pollution Caused by Methane-Air Deflagration Characteristics

Zhang¹,

Feng²,

Zhang³

et al. 2020

Rev. Chim.

1

0

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In order to study the effect of combustible gas cloud releasing from FPSO upper deck facilities deflagration characteristics on air pollution, a semi-open open test pipe system was built. By changing the initial conditions such as the obstacles length, distance between obstacles, section shape of obstacles and pipe system structure, the flame propagation mechanism and overpressure changing rules of methane / air deflagration were analyzed. As a result of that, the degree of sufficiency of methane combustion was analyzed, which could be seen as air pollution level. With the increase of the length of obstacle and decrease of the distance between obstacles, the induced turbulence increased, the compression effect of unburned gas became stronger, the combustion of combustible gas became more intense and sufficient, and the flame propagation speed and the maximum overpressure increased. The effect of square cross section was more obvious on inducing turbulence than that of rectangular cross section and circular cross section. The flame front was divided into many small flames by the pipe structure obstacle, and the flame front showed as a `spiny` shape. Under the effect of �spiny� flame, the methane combustion was more sufficient, and the maximum overpressure value was 3.1 times of the circular section obstacle condition. In conclusion, as the methane-air deflagration becoming more serious, although the overpressure and flame speed would be higher and the extent of damage to the surrounding facilities would be more serious, the air pollution causing by unburned gas would abate.

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Effect of bifurcation on premixed methane-air explosion overpressure in pipes

Cited by 31 publications

References 17 publications

Effect of Different Bend Pipes on the Propagation Characteristics of Premixed Methane-Air Explosion in Confined Spaces

Effect of Different Bend Pipes on the Propagation Characteristics of Premixed Methane-Air Explosion in Confined Spaces

Influence of Cavity Width on Attenuation Characteristic of Gas Explosion Wave

Experimental Study on the Effect of Air Pollution Caused by Methane-Air Deflagration Characteristics

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