Bio: Yunji Gao is an academic researcher from Southwest Jiaotong University. The author has contributed to research in topics: Flame spread & Spontaneous combustion. The author has an hindex of 8, co-authored 44 publications receiving 178 citations. Previous affiliations of Yunji Gao include China University of Mining and Technology & Chinese Ministry of Public Security.
TL;DR: In this article, the effect of spacing between wall and thin fuels on upward flame spread was investigated for the first time using 1mm thick PMMA sheets, including two-face burning case, and experiments were performed on uniform PMMA (polymethyl-methacrylate) samples with 200mm height, 50mm width, and 1mm thickness.
Abstract: Experiments were carried out to study the effect of spacing between wall and thin fuels on upward flame spread. The front flame height, back flame height, pyrolysis height, burnout length, and pyrolysis spread rate were measured by video image analysis with spacings of 2 mm, 7 mm, 13 mm, 19 mm, and 25 mm. Experiments were performed on uniform PMMA (polymethyl-methacrylate) samples with 200 mm height, 50 mm width, and 1 mm thickness. The results are as follows: (1) As the spacing increased, the front flame height, back flame height, pyrolysis height, and burnout length showed the same trajectory, first increased and then decreased. The maximum trajectory was observed at a spacing of 6.5% of the wall height. (2) At an infinite length of PMMA, the pyrolysis zone and pyrolysis spread rate would reach an asymptotic steady state, and the pyrolysis and burnout spread rates will be asymptotically equal. (3) Of particular interest is the maximum mass-loss rate for a wall spacing/sample height ratio (0.065) due to enhanced the radiation fluxes. In this study, the effects of spacing between wall and fuels on upward flame spread was investigated for the first time using 1 mm thick PMMA sheets, including two-face burning case.
TL;DR: In this paper, the longitudinal and cross-sectional temperature distributions are measured in reduced-scale tunnel fire experiments with different fire power conditions, and the results from the burning experiments are analyzed.
TL;DR: In this paper, the influence of vertical channel with various structure factors (α) on downward flame spread over extruded polystyrene (XPS) foam is investigated, and a model is established to predict the total, convective and radiative heat fluxes transferred to preheating zone.
TL;DR: In this article, the authors investigated the ceiling maximum smoke temperature and longitudinal decay in tunnel fires using a horseshoe shaped 1:3.7 scale-model tunnel constructed by concrete and a full-scale model tunnel established by SIMTEC for the first time.
TL;DR: In this paper, the authors investigated the spontaneous ignition of high-pressure hydrogen during its sudden release into the L-shaped tube and found that the reflected shock wave moving forward is reflected several times by the tube wall until it disappears and oblique shock is generated.
01 Jan 2016
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TL;DR: In this article, the effects of hydrogen fraction and explosion venting duct length on jet flame propagation characteristics of premixed H2-air mixtures were analyzed through experiment and simulation, showing that when hydrogen fraction was high enough, part of the unburned hydrogen was mixed with air to reach an ignitable concentration, resulting in the secondary combustion was easier produced and the duration of the secondary flame increased.
TL;DR: In this paper, the authors explored the basic characteristics of the underexpansion jet flame in premixed H2/air explosion venting, and discussed the formation of two under-expansion structures (Mach disk and diamond shock wave) of such jet flames.
TL;DR: A dynamic quantitative risk analysis method for natural gas pipelines in a utility tunnel is developed that provides a predictive analysis of the gas pipeline accident evolution process from causes to consequences and examines key challenges in gas pipeline risk management in utility tunnels.
Abstract: With rapid urbanization in China, many underground utility tunnels have been established these years. This huge underground construction facilitates city life, but may introduce societal risks due to the installation of high‐risk pipelines. Natural gas pipelines have the potential to cause catastrophic accident if a gas leakage and a subsequent explosion occurs. The potential hazards in the gas compartments of a utility tunnel are quite different from those in conventional directly buried gas pipelines. This study developed a dynamic quantitative risk analysis method for natural gas pipelines in a utility tunnel. First, potential accident scenarios of natural gas pipelines situated in a utility tunnel were identified and implemented in a Bow‐tie diagram based on case studies of typical gas pipeline accidents and expert experience. Then, a Bayesian network was established from the Bow‐tie diagram using a mapping algorithm. Based on a comprehensive analysis of the results of probability updating and sensitivity analysis, critical influencing factors were identified. The proposed framework provides a predictive analysis of the gas pipeline accident evolution process from causes to consequences and examines key challenges in gas pipeline risk management in utility tunnels. © 2019 American Institute of Chemical Engineers Process Saf Prog: e12051 2019
TL;DR: In this article, the authors revisited the problem of opposed fire spread under limited and excessive oxygen supply and reviewed various near-limit fire phenomena, as recently observed in flaming, smoldering, and glowing spread under various environment and fuel configurations.