Pressure loading of detonation waves through 90-degree bend in high pressure H2–O2–N2 mixtures

Uchida, Masahiro; Suda, Toshiyuki; Fujimori, Takahiro; Fujii, Tadashi; Inagaki, Tetsuhiko

doi:10.1016/j.proci.2010.06.152

Cited by 12 publications

(9 citation statements)

References 10 publications

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“…The maximum overpressures and velocities obtained from Figure 2 and 3 were 8-11 barg and 300-600 m/s, respectively. As mentioned earlier, the high compression effect was observed at the end of the pipe (straight pipe), thus, it can be said that the steep pressure rise (detonationlike) was affected by the strong interaction between the hot flame and reflected shock/acoustic wave, due to the highly compressed flame front [22,27]. The condition occurs when an initially laminar flame is hit head-on by the shock waves, producing a sudden release of pressure [22].…”

Section: Overpressure Along Pipementioning

confidence: 92%

“…The condition occurs when an initially laminar flame is hit head-on by the shock waves, producing a sudden release of pressure [22]. This release sends a strong rarefaction wave to propagate back into the unburned gases, that creates an unburned gas jet, penetrating the burned gas and developing the shear layers, subsequently produces an extreme turbulence that causes a sudden increase in the burning rate whereby 'trains' of compressed waves are formed [22,27]. A study by Karlovitz et al, [28] suggested that the wrinkling of the flame front (turbulisation) can be so great, such that the pockets of trapped unburned gas preheat and collapse in a strong reaction burst.…”

Section: Overpressure Along Pipementioning

confidence: 99%

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Effect of pipe size on acetylene flame propagation in a closed straight pipe

Zubaidah¹,

Kasmani²,

Mustafa³

et al. 2017

J. MECH. ENG. SCI.

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The understanding of flame propagation mechanism in a tube or pipe as a function of scale is needed to describe explosion severity. Acetylene is an explosively unstable gas and will lead to a violent explosion when ignited. To achieve the goal, an experimental study of premixed acetylene/air mixture at stoichiometry concentration was carried out in a closed straight pipe with different sizes of L/D (ratio of length to diameter) to examine the flame propagation mechanism. Pipes with L/D=40 and 51 were used. From the results, it was found that the smaller pipe with L/D=40 enhanced the explosion severity by a factor of 1.4 as compared to that of the bigger pipe with L/D=51. The compression effect at the end of the pipe plays an important role to attenuate the burning rate, leading to higher flame speeds and hence, increases the overpressure. In the case of L/D=40, the compression effect is more severe due to the larger expansion ratio, and this phenomenon would decrease the quenching effect and subsequently promote flame acceleration. Fast flame speeds of up to 600 m/s were measured in the smaller pipe during explosion development. From the results, it can be seen that the compression effect plays a major role in contributing to the higher burning rate and affects the overall explosion and flame speed development. Furthermore, the compression effect is more severe in the smaller pipe that leads to the detonation-like event. This mechanism and data are useful to design a safety device to minimise explosion severity.

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Section: Overpressure Along Pipementioning

confidence: 92%

Section: Overpressure Along Pipementioning

confidence: 99%

Effect of pipe size on acetylene flame propagation in a closed straight pipe

Zubaidah¹,

Kasmani²,

Mustafa³

et al. 2017

J. MECH. ENG. SCI.

View full text Add to dashboard Cite

show abstract

“…The results showed that obstacles promoted the acceleration of hydrogen flame in the experimental pipe section. In terms of pipe structure, Uchida et al [7] studied the influence of explosion wave on the internal pressure of pipeline in 90° elbow, and the results determined that the pressure load of elbow in two positions was greater than that of straight pipe. One is the peak pressure at the outer edge of the bend due to compression.…”

Section: Introductionmentioning

confidence: 99%

The effect of pipe-line structure on the flammability characteristics of hydrogen-air premixed gas under end-opening conditions

Zhou

Chen

et al. 2023

THERM SCI

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The pipe structures and opening conditions have an important influence on gas explosion, but little research has been done on the coupling analysis of the two. In order to reveal the effect of pipe structure on the flammability characteristics of hydrogen-air premixed gas under end-opening conditions, the flame structure, flame propagation velocity, explosion pressure and flow field distribution in the explosion process of hydrogen-air premixed gas in different pipe structures were analyzed by numerical simulation. The results show that the flame propagation velocity and pressure are less influenced by the end-opening structure in the initial ignition stage, however, when the flame propagates to the pipe end, the flame propagation velocity in each pipe structure is significantly enhanced. The 90? elbow has a certain inhibitory effect on the flame development, while the T-shaped bifurcation structure can effectively increase the degree of gas detonation. In pipe with large aspect ratio, due to the wall effect, the effect of acoustic oscillation disturbance on the flame front and the airflow release effect of the end-opening, there are two peaks and two troughs in the pressure rise rate curve of each pipeline structure.

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“…Edwards [19] studied the shock wave propagation in 90-degree bend by experiment and points out the relationship between the shock wave velocity and the curvature of the pipe. Frolov [20,21] investigated the detonation wave propagation characteristics of the U-bend tubes by experiment and numerical simulation Uchida [22] explored a comparative study on detonation wave propagation in 90 • straight tube and bend and points out two locations in pipe where pressure values are greater than those in the straight tube. One location is in the outer wall surface of bend and the other appears in the downstream of the bend exit because of the effect of transverse waves.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Pipe Bending Curvature on H2-O2 Gaseous Detonation Wave Front

Zhao

et al. 2021

Applied Sciences

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The influence of different bend curvatures on the detonation wave propagation was analyzed by an advanced numerical simulation system. The mechanism of propagation properties is revealed by cellular structure, internal and external boundary pressure distribution, propagation process of detonation wave and chemical reaction. The cellular structure and detonation wave front of bend with different curvature are very different. The simulation results show that the detonation wave with regular cell structure propagating through the curved parts induces detonation cell size increased by diffraction near the inner wall while detonation reflected on the bottom surface resulting in decrease of cell size. Detonation wave was affected by the rarefaction wave and compression wave in the bent pipe. The pressure distribution of the bend shows that the peak pressure in the 450 curvature is the largest, which should be paid more attention in industrial design. The chemical reaction could indicate the propagation characteristics of detonation wave, and different propagation characteristics have different profiles of chemical components.

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Pressure loading of detonation waves through 90-degree bend in high pressure H2–O2–N2 mixtures

Cited by 12 publications

References 10 publications

Effect of pipe size on acetylene flame propagation in a closed straight pipe

Effect of pipe size on acetylene flame propagation in a closed straight pipe

The effect of pipe-line structure on the flammability characteristics of hydrogen-air premixed gas under end-opening conditions

The Influence of Pipe Bending Curvature on H2-O2 Gaseous Detonation Wave Front

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