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Gas explosion is one of the most major types of accident in mining projects, and the flame front with high temperature is major hazardous factor induced by this kind of accident. Support engineering provides an available way to solve problems related to ground movements, but very likely has a great influence on the gas explosion accident process, especially the flame propagation, and then aggravates mining risk. However, until now it has not been received much attention from scientific works. The paper aims to discuss these issues.

A commercial CFD software package AutoReaGas suitable for gas explosion is used to carry out the numerical investigation of gas explosion process in a straight coal tunnel with typical support engineering, especially the unsteady explosion field and the flame propagation process in it.

Support engineering composed by multiple bars take positive influence on flame acceleration: the flame speed is much faster than that under no support bars, and the smaller support spacing induces greater flame speed near the ignition. The support bars also exert negative influence on flame acceleration: the larger support spacing induces greater flame speed in most region of the tunnel. Furthermore, a traditional viewpoint that denser obstacles induce greater explosion effects is one-sided according to this study.

At present, no one concerns the aggravating influence of support engineering on accident risk in practical mining projects because of small geometric dimension. This work examines the effect of steel support system on evolution processes of gas explosion accidents, especially the flame propagation. The conclusions provide quantitative scientific basis for this kind of the accidents in risk evolution and accident investigation of mining engineering.

The purpose of this paper is to ascertain the harm to personnel and equipment caused by an external explosion during natural gas explosion venting. The external explosion characteristics induced by the indoor natural gas explosion are the focal points of the investigation.

Computational fluid dynamics technology was used to investigate the large-scale explosion venting process of natural gas in a 6 × 3 × 2.5 m room, and the characteristics of external explosion under different scaled vent size (K_v = A_v/V2/3, 0.05, 0.08, 0.13, 0.18) were numerically analyzed.

When K_v = 0.08, the length and duration of the explosion fireball are 13.39 and 450 ms, respectively, which significantly expands the degree and range of high-temperature hazards. The suitable flow-field structure causes the external explosion overpressure to be more than twice that indoors, i.e. the natural gas explosion venting overpressure may be considerably more hazardous in an outdoor environment than inside a room. A specific range for the K_v can promote the superposition of outdoor rupture waves and explosion shock waves, thereby creating a new overpressure hazard.

Little attention has been devoted to investigating systematically the external explosion hazards. Based on the numerical simulation and the analysis, the external explosion characteristics induced by the indoor large-scale gas explosion were obtained. The research results are theoretically significant for mitigating the effects of external gas explosions on personnel and equipment.

Explosions are the main type of accident causing casualties in underground coal mines. Little attention has been devoted to investigating the flame propagations for methane‐air explosion in a tunnel with full scale. This paper seeks to address this topic.

Based on the numerical simulation and the analysis, the propagation rule of flame and temperature waves inside and outside the space occupied by methane/air mixture at the various concentrations in a tunnel were obtained in this work.

The original interface of methane‐air mixture and air moves forward in the explosion and the original mixture area extends. For the methane‐air mixture with rich fuel concentration, the flame speed increases with distance within a range beyond the original position of the interface between the mixture and air. The flame speed reaches maximum value outside the original area of methane‐air mixture with rich fuel concentration.

Based on the numerical simulation and the analysis, the propagation rule of flame and temperature wave inside and outside the space occupied by methane/air mixture at the various concentrations in a tunnel were obtained.

The purpose of this paper is to understand a flameproof distance necessary to avoid the flame harms to underground personnel which may have great significance to the safety of underground personnel and the disaster relief of gas explosions in coal mines.

Through a roadway with a length of 100 m and a cross-section area of 80 mm×80 mm, the flame propagation of premixed methane-air deflagrations were simulated by using AutoReaGas software for various fuel concentrations (7, 8, 9.5, 11, and 14 percent), fuel volumes (0.0128, 0.0384, 0.064, and 0.0896 m3), initial temperatures (248, 268, 288, 308, and 328 K), and initial pressures (20, 60, 101.3, 150, and 200 kPa).

The maximum combustion rate for each point follows a changing trend of increasing and decreasing with the distance increasing from the ignition source, and it increases with the fuel volume increasing or the initial pressure increasing, and decreases with the initial temperature increasing. However, increasing the initial temperature increases the flame arrival time for each point. The flameproof distance follows a changing trend of increasing and decreasing with the fuel concentration increasing, and it linearly increases with the fuel volume increasing or the initial temperature increasing. However, the flameproof distances are all 17 m for various initial pressures.

Increasing initial temperature increases flame arrival time for each test point. Flameproof distance increases and then decreases with fuel concentration increasing. Increasing fuel volume or initial temperature linearly increases flameproof distance. Initial pressure has little impact on the flameproof distance.

The reaction dynamics of combustible clouds at high temperatures and pressures are a common form of energy output in aerospace and explosion accidents. The cloud explosion process is often affected by the external initial conditions. This study aims to numerically study the effects of airflow velocity, initial temperature and fuel concentration on the explosion behavior of isopropyl nitrate/air mixture in a semiconstrained combustor.

The discrete-phase model was adopted to consider the interaction between the gas-phase and droplet particles. A wave model was applied to the droplet breakup. A finite rate/eddy dissipation model was used to simulate the explosion process of the fuel cloud.

The peak pressure and temperature growth rate both decrease with the increasing initial temperature (1,000–2,200 K) of the combustor at a lower airflow velocity. The peak pressure increases with the increase of airflow velocity (50–100 m/s), whereas the peak temperature is not sensitive to the initial high temperature. The peak pressure of the two-phase explosion decreases with concentration (200–1,500 g/m³), whereas the peak temperature first increases and then decreases as the concentration increases.

Chain explosion reactions often occur under high-temperature, high-pressure and turbulent conditions. This study aims to provide prevention and data support for a gas–liquid two-phase explosion.

Sustained turbulence is realized by continuously injecting air and liquid fuel into a semiconfined high-temperature and high-pressure combustor to obtain the reaction dynamic parameters of a two-phase explosion.

A BRIEF discussion of combustion research, which has been in progress for over three hundred years, must be limited to a specific subdivision of the field. For presentation before the Society of Automotive Engineers, it is logical that this report should be confined, in a general way, to that phase of combustion research which is concerned with explosions in gases, and particularly with explosions from which, through the medium of the internal combustion engine, usable power may be derived.

The purpose of this paper is to study propagation characteristics of methane explosion in the pipe network and analyze the propagation laws of methane explosion wave along the elbow pipe and pipe network.

Numerical simulation using software package AutoReaGas, a finite-volume computational code for fluid dynamics suitable for gas explosion and blast problems, is adopted to simulate the propagation characteristics of methane explosion and the property of flow field in complex structures.

Due to reflection effects of corners of elbow pipe, the peak overpressures at corner locations in the elbow pipe go about two times higher than that in the straight pipe. In the parallel pipe network, the peak overpressure increases significantly at the intersection point, while the flame speed decreases at the junction. All these indicate that pipe corners and bifurcations could substantially enhance explosion partly which can bring more severe damage at the corner area. The explosion violence is strengthened after flames and blast waves are superimposed, such that equipments and people in these areas need special strengthening protection.

The numerical results presented in this paper may provide some useful guidance for the design of the underground laneway structures and to take protective measures at corners and bifurcations in coal mines.

Two interesting papers on crakcase explosions in diesel engines were presented at the recent Oil and Gas Power Conference, of the American Society of Mechanical Engineers at Dallas, Texas. In the first paper “Diesel Engine Crankcase Explosion Investigation”, given by G. W. Ferguson of the Texas Company, the author drew attention to the conflicting opinions as to the composition and state of the crankcase atmosphere in a normally operated Diesel engine and the mechanism of ignition and subsequent propagation of flame throughout the crankcase atmosphere.

November 14, 1969 Contract — Construction — Supply of gas — Indemnity — Consumers to indemnify gas board against claims for injury or damage “caused by any action … of the consumers, their servants or agents whether arising directly or indirectly out of the supply of any gas or apparatus” — Escape of gas from faulty main — Explosion touched off by act of consumers' employee — Negligence — Board mainly liable v Whether entitled to be indemnified for own negligence.