Overpressure prediction of combustible gas explosion in confined space
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摘要: 为避免密闭空间内可燃预混气体爆炸事故造成的伤害,对其进行较为准确的爆炸超压预测是抗爆设计和日常安全管理的关键。结合已有文献实验数据,利用光滑层流火焰传播理论模型建立了爆炸超压模型;对比发现,当体积较大时,光滑层流火焰传播理论模型存在较大的误差。较大体积密闭空间爆炸火焰传播过程中的不稳定性造成火焰前锋面褶皱并引起湍流燃烧,导致火焰前锋面表面积大幅增加,且在火焰传播过程中表现出自相似分形特征。依据褶皱及湍流火焰传播过程中的自相似分形特征,基于分形燃烧理论和相关经验数据,进一步建立了考虑可燃预混气体爆炸火焰褶皱及湍流火焰传播的爆炸超压预测模型,并与实验所得结果进行了对比。结果表明:当密闭空间体积较大时,利用褶皱及湍流火焰传播理论建立的爆炸超压模型进行峰值压力估算时,两种工况下实验所得和理论计算所得相对误差分别为10.4%和11.1%,较光滑层流火焰传播理论爆炸超压模型相比,误差分别减少了72.3%和50.6%。本文所建立理论模型与实验所得结果具有较好的一致性,在一定程度上可满足结构抗爆设计或日常安全管理的需要。Abstract: In order to avoid damages caused by the explosion of combustible premixed gas in confined space, it is vital to make accurate explosion overpressure prediction in anti-explosion design or daily safety management. Based on the experimental data in literatures, this paper firstly constructd the prediction model of explosion overpressure based on the smooth and laminar flame propagation theory, and then points out it failed to accurately predict the explosion of large-volume confined space. Subsequently we analyzed the instability of flame propagation in large-volume confined space and its resulting frontal wrinkles and turbulent combustion, which greatly increases the surface of the flame front and exhibits self-similar fractal characteristics during flame propagation. Based on the fractal combustion theory and relevant empirical data, we further construct the explosion overpressure prediction model for flammable premixed gas explosion with considering flame wrinkling and turbulent combustion. At the same time, the experimental results are compared. The results demonstrate that the relative errors of experimental and theoretical calculation are 10.4% and 11.1% respectively when the volume of confined space is large, and the peak pressure is estimated by using the explosion overpressure model based on the flame propagation theory of wrinkling and turbulent. The errors are reduced 72.3% and 50.6% than that of the smooth and laminar flame propagation theory explosion overpressure model. The theoretical model established in this paper is in good agreement with the experimental results, and it can meet the needs of structural explosion-resistant design or daily safety management to a certain extent.
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Key words:
- laminar flame /
- turbulent flame /
- explosion overpressure /
- predictive model
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实验 可燃气类型 体积浓度b/% 体积V/m3 初始温度T0/K 初始压力P0/MPa SL/(cm·s−1) 1 CH4 10.0 0.12 298 0.1 37 2 CH4 10.0 3.80 294 0.1 35 3 H2 30.0 0.12 298 0.1 273 4 H2 29.5 6.37 373 0.1 434 表 2 实验与理论计算峰值超压值
Table 2. Peak overpressure of experimental and theoretical calculations
实验 实验超压/MPa 光滑层流火焰传播理论 褶皱及湍流理论火焰传播理论 峰值超压/MPa 相对误差/% 峰值超压/MPa 相对误差/% 1 0.76 0.76 0 − 2 2.44 0.42 82.7 2.22 10.4 3 0.75 0.72 3.0 − 4 0.45 0.15 66.7 0.50 11.1 -
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