A Novel Multiscale Methodology for Simulating Tunnel Ventilation Flows During Fires
A Novel Multiscale Methodology for Simulating Tunnel Ventilation Flows During Fires
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DOI：
10.1007/s10694-010-0144-2
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发表时间：
2011-01-01
期刊：
影响因子：
3.4
通讯作者：
Borchiellini, Romano
中科院分区：
文献类型：
--
作者：
Colella, Francesco;Rein, Guillermo;Borchiellini, Romano
本文采用一种新颖的快速建模方法来模拟火灾期间的隧道通风流动。通过有效地结合一维（1D）和CFD（3D）建模技术，避免了完整CFD模型的复杂性和高成本以及简单区域或分析模型的不准确性。一个简单的1D网络方法被用来模拟隧道区域的流动是充分发展（远场），和详细的计算流体动力学表示使用的流动条件需要3D分辨率（近场）。这种多尺度方法先前已被应用于模拟隧道通风系统，包括射流风扇、垂直竖井和入口（Colella等人，Build Environ 44（12）：2357-2367，2009），此处应用它是为了包括火灾的影响。直接和间接的耦合策略进行了研究和比较的稳态条件。该方法已被应用到一个现代化的隧道直径为7米，长度为1.2公里。不同的火灾情况下，从10兆瓦到100兆瓦的研究与可变数量的工作射流风机。冷流情况与火灾情况的比较提供了火灾节流效应的量化，这被认为是大的，并减少了超过30%的流量为100兆瓦的火灾。重点讨论了不同的耦合方法和数值误差的控制。与完整的CFD解相比，最大流场误差可以减少到小于几个单位，但计算时间减少了两个数量级。低得多的计算成本是很大的工程价值，特别是在通风和消防安全系统的设计或评估所需的参数和灵敏度研究。
This paper applies a novel and fast modelling approach to simulate tunnel ventilation flows during fires. The complexity and high cost of full CFD models and the inaccuracies of simplistic zone or analytical models are avoided by efficiently combining mono-dimensional (1D) and CFD (3D) modelling techniques. A simple 1D network approach is used to model tunnel regions where the flow is fully developed (far field), and a detailed CFD representation is used where flow conditions require 3D resolution (near field). This multi-scale method has previously been applied to simulate tunnel ventilation systems including jet fans, vertical shafts and portals (Colella et al., Build Environ 44(12): 2357-2367, 2009) and it is applied here to include the effect of fire. Both direct and indirect coupling strategies are investigated and compared for steady state conditions. The methodology has been applied to a modern tunnel of 7 m diameter and 1.2 km in length. Different fire scenarios ranging from 10 MW to 100 MW are investigated with a variable number of operating jet fans. Comparison of cold flow cases with fire cases provides a quantification of the fire throttling effect, which is seen to be large and to reduce the flow by more than 30% for a 100 MW fire. Emphasis has been given to the discussion of the different coupling procedures and the control of the numerical error. Compared to the full CFD solution, the maximum flow field error can be reduced to less than few percents, but providing a reduction of two orders of magnitude in computational time. The much lower computational cost is of great engineering value, especially for parametric and sensitivity studies required in the design or assessment of ventilation and fire safety systems.