Research on Gas Explosion Pressure and Flame Propagation Characteristics in Turning Pipelines.

In order to investigate the overpressure and flame propagation characteristics of gas explosions in turning pipelines, this study designed a transparent organic glass pipeline test system with different turning angles (30°, 60°, 90°, 120°, and 150°) and conducted a series of experimental studies to analyze the explosion shock wave overpressure and flame propagation behavior. The experimental results show that with the increase of the turning angle of the pipeline, the overpressure of the explosion shock wave significantly increases. In terms of flame propagation characteristics, when the turning angle is small, the flame can adhere to the outer wall of the pipeline corner and gradually fill the entire pipeline section.

Determination of Effective Radius under the Condition of Nonuniform Gas Occurrence and Borehole Plastic Failure.

In order to solve the problem of the blindness of borehole layout when the nonuniform occurrence of gas and the neglect of plastic failure around the borehole will underestimate the gas production, a gas-solid coupling model is established for considering plastic failure. The finite element software COMSOL Multiphysics is used to investigate the evolution of the effective radius during the nonuniform occurrence of gas, and the relationship between the effective radius and the borehole spacing is determined. The results show that the permeability around the borehole increases significantly when plastic failure is considered and the rising area is butterfly shaped, with a maximum increase of 94 times.

Research on Hydraulic Fracturing Pressure Relief and Improvement Permeability Technology of the Soft Coal Seam Roof.

Aiming at the characteristics of low permeability and large gas content of deep soft coal seam, hydraulic fracturing pressure relief and improvement permeability technology of the roof are proposed. FLAC was used to invert the roof hydraulic fracturing of the soft coal seams. On this basis, the dynamic evolution characteristics of permeability before and after fracturing were given by the COMSOL multiphysics software.

Online evaluation method of coal mine comprehensive level based on FCE.

An online evaluation method of coal mine comprehensive level based on Fuzzy Comprehensive Evaluation method (FCE) is proposed. Firstly, following the principles of fairness, systematicness and hierarchy, taking research and development, production, sales, finance, safety and management as the first level indicators, a set of multi-level evaluation indicator system of coal mine comprehensive level combining objective and subjective evaluation indicators is established. Secondly, according to the characteristics of the indicator system, the specific process of FCE of coal mine comprehensive level is given.

Synergistic inhibition effect on the self-acceleration characteristics in the initial stage of methane/air explosion by CO and ultrafine water mist.

Cellular instability is responsible for the self-acceleration of a flame, and such acceleration might cause considerable damage. This paper presents an experimental study on the inhibition effect of CO and an ultrafine water mist on the self-acceleration characteristics of a spherical flame in the initial stage of a 9.5% methane/air explosion in a constant volume combustion bomb.