Turbulence, Vortex and External Explosion Induced by Venting
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摘要: 基于k-ε湍流模型和Eddy-dissipation燃烧模型，采用同位网格SIMPLE算法，对充满甲烷-氧气预混气的带导管柱形泄爆容器向空气中泄爆的情形进行了数值模拟．根据计算结果，分析了泄爆后外流场中可燃云团、火焰和压力的变化过程．结果表明，外部爆炸是因射流火焰点燃高压区中的可燃云团，从而引起的剧烈湍流燃烧所致．同时还讨论了外流场湍流和涡量的分布特征．射流火焰进入外部可燃云团后，湍流主要分布在平均动能梯度较大的区域，而不在火焰阵面上．涡量分布主要受斜压效应的影响，在压力和密度梯度斜交区域，其值较大．Abstract: The process of explosion venting to air in a cylindrical vent vessel connected to a duct,filling with a stoichiometric methane-oxygen gas mixture,was simulated numerically by using a colocated grid SIMPLE scheme based on k-epsilon turbulent model and Eddy-dissipation combustion model. The characteristics of the combustible cloud,flame and pressure distribution in the external flow field during venting were analyzed in terms of the predicted results.The results show that the external explosion is generated due to violent turbulent combustion in the high pressure region within the external combustible cloud ignited by a jet flame.And the turbulence and vortex in the external flow field were also discussed in detail.After the jet flame penetrating into the external combustible cloud,the turbulent intensity is greater in the regions with greater average kinetic energy gradient,rather than in the flame front;and the vortex in the external flow field is generated primarily due to the baroclinic effect,which is greater in the regions where the pressure and density gradients are nearly perpendicular.
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Key words:
- explosion /
- vented explosion /
- external explosion
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