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

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Jinwei Qiu ◽  
Bingyou Jiang ◽  
Mingyun Tang ◽  
Liang Zhou ◽  
Bo Ren
Keyword(s):  
Shock Wave ◽  
Attenuation Coefficient ◽  
Propagation Characteristics ◽  
Gas Explosion ◽  
Bending Angle ◽  
Pipe System ◽  
Confined Spaces ◽  
Air Explosion ◽  
Gas Volume ◽  
Initial Peak

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.

Study on Hazard Effects of Gas Explosion in Coal Laneways

2011 ◽  
Vol 402 ◽  
pp. 846-849
Author(s):  
Lei Pang ◽  
Tong Wang ◽  
Yu Shu Xie ◽  
Wei Yao ◽  
Qi Zhang
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Temperature Field ◽  
High Temperature ◽  
Flame Front ◽  
Axial Distance ◽  
Distribution Characteristics ◽  
Gas Explosion ◽  
Flame Region ◽  
Air Explosion

Methane-air explosion is one of the main accidents in coal mines. In this paper, the hazard effects of the gas explosion in a long straight coal laneway were studied by virtue of numerical simulation. Distribution characteristics of the shock wave overpressure, the flame speed and the temperature field were obtained. Along the increasing axial distance, shock wave overpressure increases in original methane-air area and decreases beyond the original methane-air area. Range of flame exceeds original methane-air area. Flame accelerates continually in original methane-air area and decelerates beyond the original methane-air area. The temperature attenuates slowly along the increasing distance in the flame area by virtue of flame front, and attenuates quickly along the increasing distance beyond the flame region. High temperature hazard involves farther area beyond original methane-air area.

Experimental Study on Propagation Characteristics of Gas Explosion Shock Wave while Pipe Turning

2014 ◽  
Vol 962-965 ◽  
pp. 919-925
Author(s):  
Yuan Fu ◽  
Ji Ren Wang ◽  
Bao Shan Jia
Keyword(s):  
Shock Wave ◽  
Attenuation Coefficient ◽  
Coal Mine ◽  
Shock Pressure ◽  
Gas Explosion ◽  
Turning Angle ◽  
Coal Mine Gas ◽  
Gas Disaster ◽  
Initial Shock

Coal mine gas disaster has the characteristic of destructive and complexity, in connection with the frequently of coal mine gas disaster, the paper studied on the propagation of gas explosion shock wave while pipe cross-sectional area changing from the experimental angle, designed the test system, the data of shock wave pressure when the pipe turning angle more or less than 90 degree was given, analyzed two situations: one was to analysis the influence of initial shock pressure effect on the attenuation coefficient under determination of pipeline turning angle; another was to analysis the influence of pipe turning angles effect on the attenuation coefficient under determination of initial shock wave overpressure, pointed out that the shock wave initial pressure and pipe turning angles were the two important factors which affect the shock wave overpressure attenuation coefficient. By comparison, the initial shock pressure had the larger influence. At last, the shock wave overpressure attenuation coefficient diversification formula was given when pipe turning angles was more or less than 90 degree.

Coupling effects of foam ceramics on the flame and shock wave of gas explosion

2012 ◽  
Vol 50 (4) ◽  
pp. 797-800 ◽  
Author(s):  
Jinfeng Zhang ◽  
Zhongqiang Sun ◽  
Yanmin Zheng ◽  
Zhaogui Su
Keyword(s):  
Shock Wave ◽  
Gas Explosion ◽  
Coupling Effects

Discussion on plasma shock waves generated by high-power pulsed laser

2003 ◽  
Vol 793 ◽  
Author(s):  
ZhiHua Li ◽  
DuanMing Zhang ◽  
Li Guan
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Pulsed Laser ◽  
Point Explosion ◽  
Propagation Characteristics ◽  
The Difference ◽  
Plasma Shock Wave ◽  
First Time ◽  
Plasma Shock ◽  
The Ideal

ABSTRACTSedov-Taylor theory is modified to describe plasma shock waves generated in a pulsed laser ablating process. Under the reasonable asymptotic behavior and boundary conditions, the propagating rules in the global free space (including close areas and mid-far areas) of pulsed-laser-induced shock waves are established for the first time. In particular, the temporal behavior of energy causing the difference of the propagation characteristics between the practical plasma shock wave and the ideal shock wave in point explosion model is discussed in detail.

scholarly journals Explosion disaster distribution characteristics and outlet open-close effect of turning roadway

2020 ◽  
Author(s):  
Pengfei Lv ◽  
Minghua Ju ◽  
Jiaxu Zhang ◽  
Lei Pang ◽  
Kai Yang
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Human Body ◽  
Nonlinear Dynamic Analysis ◽  
Distance Effect ◽  
Distribution Law ◽  
Destructive Effect ◽  
Bending Angle ◽  
Finite Element Program ◽  
Minimal Impact

Abstract In this study, under the open-close conditions of a roadway outlet, the nonlinear dynamic analysis finite element program ANSYS/LS-DYNA was used to build models of explosions on roadways with 0˚ and 90˚ bending angles, to compare and analyse the shock wave propagation characteristics and variation laws. Moreover, the destructive effect of the explosion on the partition was analysed based on the level of damage caused to the human body by shock wave overpressure. The results show that the bending angle has an impact on the space-time distribution law of the explosion shock waves on the roadway. As the bending angle increases, the peak overpressure attenuation of the shock waves becomes prominent, and the arrival time for the same distance increases. The closure of the roadway outlet has a distance effect on the peak overpressure of the shock waves. The explosion shock waves cause the peak overpressure to rise sharply owing to the reflection and stacking effects near the closure. In the far zone of the outlet, the attenuation of the shock waves is too fast and has minimal impact on the peak overpressure. Additionally, overall, the closure of the roadway outlet increases the damage range of the explosion shock waves and the severity of their effect on the human body. With an increase in the bending angle, the damage range and severity decrease. These results can provide a reference for explosion disaster evaluation and prevention.

scholarly journals Experimental Study on the Damage Characteristics of Polymer Slabs Subjected to Air Contact and Close-In Explosions

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Zhidong Liu ◽  
Xiaohua Zhao ◽  
Hongyuan Fang ◽  
Xueming Du ◽  
Binghan Xue ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shock Wave ◽  
Failure Mode ◽  
Explosive Charge ◽  
Time History ◽  
Dynamic Mechanical Properties ◽  
Charge Weight ◽  
Pressure Time ◽  
Static Mechanical ◽  
Air Explosion

As a new antiseepage reinforcement material, polyurethane grouting material has been widely studied in terms of its static mechanical properties. However, research on its dynamic mechanical properties is relatively rare. In this research, considering the influence of the explosive charge weight, the air contact and close-in explosion experiments of polymer slabs were carried out. The failure mode and damage spatial distribution characteristics of polymer slabs were explored. Pressure time history curve of air shock wave was obtained using an air shock wave tester. The influence of polymer slabs on the propagation of air explosion shock wave was compared and analyzed. The results show that, under the air contact explosion, the polymer slab mainly suffers local damage, while under close-in explosion, overall damage is the main damage mode. With the increase of the explosive charge weight, the failure mode of the polymer slab transits from surface crack and slight spalling to local and whole crushing.

Influence of Moisture of Wheat on Acoustic Wave Propagation Characteristics

2020 ◽  
Vol 63 (5) ◽  
pp. 1315-1326
Author(s):  
Chi Zhang ◽  
Aini Dai ◽  
Haiying Yang ◽  
Zidan Wu ◽  
Xiaoguang Zhou ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Moisture Content ◽  
Acoustic Wave ◽  
Attenuation Coefficient ◽  
Wave Velocity ◽  
Propagation Constant ◽  
Pso Algorithm ◽  
Average Radius ◽  
Propagation Characteristics ◽  
Acoustic Wave Propagation

HighlightsA novel measuring device was developed for the propagation constant of acoustic waves in grain.Increase in moisture of wheat from 1.1% to 7.8% (wet basis) decreased the wave velocity and increased the attenuation coefficient.Increase in moisture of wheat from 7.8% to 21.2% increased the wave velocity and decreased the attenuation coefficient.Using the Johnson-Champoux-Allard (JCA) model and particle swarm optimization (PSO) algorithm, the influence of moisture on the pore structure in wheat was characterized.Abstract. Acoustic methods have been widely used for the measurement of grain moisture content and temperature as well as for detecting the presence of insects in grain. Therefore, this study was conducted to understand the influence of wheat moisture content on acoustic wave propagation characteristics. A novel device was developed for measuring the acoustic wave propagation constant. The propagation constants of 12 samples of wheat were measured, with each sample having a different moisture content in the range from 1.1% to 21.2% (wet basis). The results showed that the acoustic wave velocity decreased slightly with an increase in moisture from 1.1% to 7.8%, while the attenuation coefficient increased slightly. When the moisture increased from 7.8% to 21.2%, the velocity increased gradually, while the attenuation coefficient decreased. A quadratic equation described the results well. In addition, a Johnson-Champoux-Allard (JCA) model was adopted to study the influence of moisture on the pore structure of wheat samples. With the increase in moisture from 1.1% to 21.2%, the average radius of interconnection between two adjacent pores decreased from 0.275 to 0.262 mm at moisture below 7.8% and then increased to 0.304 mm, and the average radius of the pores decreased from 0.773 to 0.481 mm at moisture below 7.8% and then increased to 1.2 mm. Keywords: Acoustic standing wave tube, JCA model, Moisture content, Propagation constant, PSO algorithm, Wheat.

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