| 张首蕤,刘乃安,高威.边缘高度对中尺度正庚烷池火燃烧和流动特性影响的实验研究[J].火灾科学,2024,33(3):137-145. |
| 边缘高度对中尺度正庚烷池火燃烧和流动特性影响的实验研究 |
| Experimental study on the lip height effect on combustion and flow characteristics of n-heptane pool fire |
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| DOI：10.3969/j.issn.1004-5309.2024.03.01 |
| 基金项目:国家重点研发计划项目(2022YFC3003000);国家自然科学基金项目(51936011、52020105008);中央高校基本科研业务费(WK2320000058) |
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| 中文关键词: 边缘高度 火焰高度 速度分布 脉动频率 |
| 英文关键词:Lip height Flame height Velocity distribution Pulsation frequency |
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| 中文摘要: |
| 开展了不同边缘高度下的正庚烷池火燃烧和流动特性的实验研究,着重分析了边缘高度对火焰形态、速度分布和脉动行为的影响。结果表明,池火的火焰高度随边缘高度的增加而减小,火焰宽度随边缘高度的增加而先增加后减小,其中伴随了瑞利-泰勒不稳定性的影响。边缘高度显著增强了燃烧流动的不稳定性,影响卷吸空气流进入油盘内部的途径和方式,促进了火焰底部涡旋结构的生成。火焰出现了底部下沉现象,显著影响近场区的轴向速度分布。随着高度的增加,火焰的轴向速度分布逐渐向高斯自相似分布转变。边缘高度对火焰脉动产生了两方面的影响机制:一是促进入流空气的扰流而加剧火焰的不稳定性和震荡;二是显著影响火焰的空气入流途径,导致火焰流动和震荡减弱。这两方面机制的竞争导致了火焰脉动频率随着边缘高度增加而呈现非单调变化。 |
| 英文摘要: |
| In this study, an experimental investigation was conducted to examine the combustion and flow characteristics of n-heptane pool fires, specifically focusing on the influence of lip height on flame morphology, velocity distribution, and pulsation behavior. The results demonstrate that increasing the lip height leads to a decrease in flame height and an initial increase followed by a decrease in flame width due to Rayleigh-Taylor instability effects. Moreover, lip height significantly enhances flow instability, alters the entrained airflow pattern into the fuel pan, and promotes vortex generation at the base of the flame. As for axial height variations, there is a gradual transition from irregular to self-similar flame velocity distribution attributed to the pronounced sinking of the bottom region, affecting axial velocity distribution in near-field regions. Additionally, two mechanisms contribute to flame pulsation induced by lip height; one mechanism promotes airflow disturbance and exacerbates flame instability, while another restricts air inflow pathways, potentially weakening overall flame dynamics. The competition between these mechanisms results in a non-monotonic variation of pulsation frequency as lip height increases. |
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