Temperature distribution and flow field characteristics of multiple fire whirls in a vertical shaft
This paper investigates the temperature distribution and flow field characteristics of multiple fire whirls in a vertical shaft. The pool number n, diameter D, and dimensionless flame spacing S/D (S: flame spacing) were varied. The results suggest that the merged flame zone in multiple fire whirls i...
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| Language: | English |
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Elsevier
2025-05-01
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| Series: | Case Studies in Thermal Engineering |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2214157X25003223 |
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| author | Rongshui Qin Lingfeng He Xuesong Dai Zijian Yan Zelong Zhang Chao Ding Yan Jiao |
| author_facet | Rongshui Qin Lingfeng He Xuesong Dai Zijian Yan Zelong Zhang Chao Ding Yan Jiao |
| author_sort | Rongshui Qin |
| collection | DOAJ |
| description | This paper investigates the temperature distribution and flow field characteristics of multiple fire whirls in a vertical shaft. The pool number n, diameter D, and dimensionless flame spacing S/D (S: flame spacing) were varied. The results suggest that the merged flame zone in multiple fire whirls includes three different zones similar to pool fires, namely continuous flame, intermittent flame and plume. A simplified flame shape model is established for two pool numbers, using the flame merging point as a boundary. A correlation between the normalized height of the merged flame zone and the centerline excess temperature distribution is developed by introducing a virtual origin to represent the effect of fire geometry. The results also indicate that the increase in circulation enlarges the contact area between the flame and fuel, inducing more air into the merged flame zone and enhancing the burning rate, and an optimum flame spacing exists to maximize it. Furthermore, based on the flame trailing effect, a relationship is established for the tangent values of the outer burners’ flame tilt angles in multiple fire whirls, varying with induced wind speed under different controlling parameters. It is revealed that flame tilt angle shows a non-linear increase with wind intensity and the theoretical predictions agree well with the experimental results. Finally, numerical simulations characterize the flow distribution around multiple fire whirls. It is found that with increasing S/D, whirls are mainly concentrated in the central region of the merged flames, with the surrounding areas being relatively weaker. Simultaneously, a critical S/D exists where the maximum tangential velocity peaks, influenced by competing interactions from the flames. Besides, the maximum tangential velocity shows a monotonic increase with the increase of S/D in some experimental conditions, influenced by the number and size of pools. |
| format | Article |
| id | doaj-art-185285c5c4e446e7b2ccd5f2811cb3fd |
| institution | OA Journals |
| issn | 2214-157X |
| language | English |
| publishDate | 2025-05-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Case Studies in Thermal Engineering |
| spelling | doaj-art-185285c5c4e446e7b2ccd5f2811cb3fd2025-08-20T02:28:07ZengElsevierCase Studies in Thermal Engineering2214-157X2025-05-016910606210.1016/j.csite.2025.106062Temperature distribution and flow field characteristics of multiple fire whirls in a vertical shaftRongshui Qin0Lingfeng He1Xuesong Dai2Zijian Yan3Zelong Zhang4Chao Ding5Yan Jiao6School of Civil Engineering, Anhui Jianzhu University, Hefei, 230601, ChinaSchool of Environment and Energy Engineering, Anhui Jianzhu University, Hefei, 230601, ChinaSchool of Architecture and Urban Planning, Anhui Jianzhu University, Hefei, 230601, ChinaState Key Laboratory of Fire Science, University of Science and Technology of China, JinZhai Road 96, Hefei, Anhui, 230026, ChinaSchool of Environment and Energy Engineering, Anhui Jianzhu University, Hefei, 230601, ChinaSchool of Environment and Energy Engineering, Anhui Jianzhu University, Hefei, 230601, China; Corresponding author.School of Environment and Energy Engineering, Anhui Jianzhu University, Hefei, 230601, China; Corresponding author.This paper investigates the temperature distribution and flow field characteristics of multiple fire whirls in a vertical shaft. The pool number n, diameter D, and dimensionless flame spacing S/D (S: flame spacing) were varied. The results suggest that the merged flame zone in multiple fire whirls includes three different zones similar to pool fires, namely continuous flame, intermittent flame and plume. A simplified flame shape model is established for two pool numbers, using the flame merging point as a boundary. A correlation between the normalized height of the merged flame zone and the centerline excess temperature distribution is developed by introducing a virtual origin to represent the effect of fire geometry. The results also indicate that the increase in circulation enlarges the contact area between the flame and fuel, inducing more air into the merged flame zone and enhancing the burning rate, and an optimum flame spacing exists to maximize it. Furthermore, based on the flame trailing effect, a relationship is established for the tangent values of the outer burners’ flame tilt angles in multiple fire whirls, varying with induced wind speed under different controlling parameters. It is revealed that flame tilt angle shows a non-linear increase with wind intensity and the theoretical predictions agree well with the experimental results. Finally, numerical simulations characterize the flow distribution around multiple fire whirls. It is found that with increasing S/D, whirls are mainly concentrated in the central region of the merged flames, with the surrounding areas being relatively weaker. Simultaneously, a critical S/D exists where the maximum tangential velocity peaks, influenced by competing interactions from the flames. Besides, the maximum tangential velocity shows a monotonic increase with the increase of S/D in some experimental conditions, influenced by the number and size of pools.http://www.sciencedirect.com/science/article/pii/S2214157X25003223Multiple fire whirlsTemperature distributionCirculationFlame tilt angleCFD simulation |
| spellingShingle | Rongshui Qin Lingfeng He Xuesong Dai Zijian Yan Zelong Zhang Chao Ding Yan Jiao Temperature distribution and flow field characteristics of multiple fire whirls in a vertical shaft Case Studies in Thermal Engineering Multiple fire whirls Temperature distribution Circulation Flame tilt angle CFD simulation |
| title | Temperature distribution and flow field characteristics of multiple fire whirls in a vertical shaft |
| title_full | Temperature distribution and flow field characteristics of multiple fire whirls in a vertical shaft |
| title_fullStr | Temperature distribution and flow field characteristics of multiple fire whirls in a vertical shaft |
| title_full_unstemmed | Temperature distribution and flow field characteristics of multiple fire whirls in a vertical shaft |
| title_short | Temperature distribution and flow field characteristics of multiple fire whirls in a vertical shaft |
| title_sort | temperature distribution and flow field characteristics of multiple fire whirls in a vertical shaft |
| topic | Multiple fire whirls Temperature distribution Circulation Flame tilt angle CFD simulation |
| url | http://www.sciencedirect.com/science/article/pii/S2214157X25003223 |
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