Strategies to challenge the simulation of confined fires

Salmon F.; Mindeguia J. -C.; Lacanette D.; Sirieix C.; Leblanc J. -C.; Ferrier C.

摘要

The numerical simulation of fires concerns an increasingly wide range of applications, among which archaeology. The Chauvet-Pont d'Arc Cave (France) presents thermal marks on some of its walls. These marks result from prehistorical fires and archaeologists would like to know their characteristics (fire location, mass of fuel, number of fires, etc) to make assumptions about their functions. Being impossible to carry out fires in the cave, combustion simulation is a suitable tool to discuss this question. However, simulating a fire in a confined geometry is still challenging and some inherent difficulties must be overcome. In that respect, we reproduced four experimental fires in a cave-like geometry. Four tepee-like hearths, composed of different initial wood masses (16, 32, 60 and 90 kg), were burnt in an underground quarry. Twenty-seven thermocouples measured the temperature in the cold and hot gas layers, as well as in the ceiling jet area. The measurements in the ceiling jet resulting from the 90 kg fire are successfully compared to the corrected Delichatsios correlations. In addition, the measured mass loss rate is compared to a tailored modeling for tepee hearths. We also propose three strategies to simulate the combustion process of the 90 kg hearth: (i) with a significant refinement in the ceiling jet area (approximately 1,500,000 cells) and the law of the wall, (ii) without refinement but with Newton's law of cooling and (iii) without refinement but with simplifying assumptions and adjustments. While the first and third approaches provide meaningful results, the second case is found to be inconvenient for compartment fires. Based on experimental data, this study aims to give some keys to perform simulations of compartment fires (in tunnels, buildings, car parks, etc) and numerically approximate the combustion of wood.

机译：火灾的数值模拟涉及越来越多的应用范围，其中考古学。 Chauvet-Pont D'Arc Cave（法国）在一些墙壁上呈现热标记。这些标志是由普遍博物火和考古学家造成的，想知道他们的特征（火灾地点，燃料量，火灾数量等），以使其功能的假设。无法在洞穴中进行火灾，燃烧模拟是一个合适的讨论这个问题的工具。然而，在狭窄的几何形状中模拟火灾仍然挑战，必须克服一些固有的困难。在这方面，我们在洞穴的几何形状中复制了四次实验火灾。由不同的初始木质群体（16,32,60和90千克）组成的四个Tepee的壁炉，在地下采石场中被烧毁。二十七热电偶测量了冷热气体层中的温度，以及天花板喷射区域。与校正的Delichatsios相关相比，由90kg火灾产生的天花板射流中的测量结果。此外，将测量的质量损失率与Tepee Headths的定制建模进行了比较。我们还提出了三种策略来模拟90千克壁炉的燃烧过程：（i）在天花板喷气机面积（约1,500,000个细胞）和墙壁规律中具有显着的改进，（ii）没有细化，但与牛顿的法律冷却和（iii）无细化，但具有简化假设和调整。虽然第一个和第三种方法提供了有意义的结果，但第二个案例被发现对隔间火灾不方便。基于实验数据，本研究旨在提供一些钥匙，以进行隔室火灾的模拟（在隧道，建筑物，停车场等），并在数值上近似木材燃烧。

Strategies to challenge the simulation of confined fires

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