Predicting gas dispersion in large scale underground ventilation: A particle tracking approach
Predicting gas dispersion in large scale underground ventilation: A particle tracking approach
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DOI：
10.1016/j.buildenv.2015.07.025
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发表时间：
2016
影响因子：
7.4
通讯作者：
Arif Widiatmojo;K. Sasaki;N. Widodo;Y. Sugai;Amin Yousefi Sahzabi;R. Nguele
中科院分区：
文献类型：
--
作者：
Arif Widiatmojo;K. Sasaki;N. Widodo;Y. Sugai;Amin Yousefi Sahzabi;R. Nguele
采用示踪气体测量和粒子跟踪法数值模拟相结合的方法，对大型地下隧道通风中的气体扩散进行了评价。通风系统是控制污染物和/或有害气体扩散的工具。基于网格的数值方法的使用受到通风网络空间维数的限制。因此，该技术在大型通风网络中的适用性受到限制。提出了一种基于拉格朗日的粒子跟踪方法，用于评价复杂通风系统中示踪气体从释放点到下游位置的扩散。该方法通过将质量浓度离散为粒子数来模拟质量输运。该技术通过计算通风网络中任意位置的颗粒数来模拟质量浓度，而不是在网格系统中求解输运方程来获得质量浓度。本文采用网络分裂方法模拟了粒子在结中的跃迁过程。进一步研究发现，将有效扩散系数设置为普通地下气道的47倍，速度修正系数α = 0.59，粒子追踪结果与示踪气体测量数据吻合较好。这一结果表明，在分析的方法来评估气体（或污染物）的扩散和停留时间在大型通风系统的常规通风网络分析，必须考虑机械扩散和延迟的影响，由于气体的捕获机制。
The present work highlights the gas dispersion evaluation in large underground tunnel ventilation by means of tracer gas measurement and numerical simulation using particle tracking method. Ventilation system is a tool to control pollutants and/or hazardous gas spreading. The use of grid-based numerical method is limited by the spatial dimension of ventilation network. Therefore, the applicability of such technique for large ventilation network is constrained. A Lagrangian based Particle Tracking method is proposed to evaluate the dispersion of tracer gas from a releasing point to the downstream position in a complex ventilation system. This method simulates mass transport by discretizing mass concentration into numbers of particles. Rather to solving the transport equation in grid system to obtain the mass concentration, this technique simulates mass concentration by counting number of particles at any specified position within the ventilation network. In this research, the network splitting scheme was used to simulate particles' transition in junctions. Further, it was found that by setting effective diffusion coefficient to 47 times larger than those for common underground airway and with velocity correction factor of α = 0.59, a good agreement between particle tracking result and tracer gas measurement data can be achieved. This results suggests that the analytical approach in evaluating gas (or pollutant) dispersion and residence time in large ventilation system by the means of conventional ventilation network analysis have to consider both mechanical dispersion and the effect of delay due to trapping mechanism of gas.