Experimental Study on Effects of Lateral Spacing on Flame Propagation over Solid Fuel Matrix

The increasing complexity of urban structures has significantly elevated the risk and severity of façade fires in high-rise buildings. Unlike traditional models assuming continuous fuel beds, real-world fire scenarios often involve discrete combustible materials arranged in discrete fuel matrices. T...

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Main Authors: Xin Xu, Yanyan Ma, Guoqing Zhu, Zhen Hu, Yumeng Wang
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Fire
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Online Access:https://www.mdpi.com/2571-6255/8/7/284
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author Xin Xu
Yanyan Ma
Guoqing Zhu
Zhen Hu
Yumeng Wang
author_facet Xin Xu
Yanyan Ma
Guoqing Zhu
Zhen Hu
Yumeng Wang
author_sort Xin Xu
collection DOAJ
description The increasing complexity of urban structures has significantly elevated the risk and severity of façade fires in high-rise buildings. Unlike traditional models assuming continuous fuel beds, real-world fire scenarios often involve discrete combustible materials arranged in discrete fuel matrices. This study presents a systematic investigation into the influence of lateral spacing on vertical flame propagation behavior. Laboratory-scale experiments were conducted using vertically oriented polymethyl methacrylate (PMMA) fuel arrays under nine different spacing configurations. Results reveal that lateral spacing plays a critical role in determining flame spread paths and intensities. Specifically, with a vertical spacing fixed at 8 cm, a lateral spacing of 10 mm resulted in rapid flame growth, reaching a peak flame height of approximately 96.5 cm within 450 s after ignition. In contrast, increasing the lateral spacing to 15 mm significantly slowed flame development, achieving a peak flame height of just under 90 cm at approximately 600 s. This notable transition in flame dynamics is closely associated with the critical thermal boundary layer thickness (~11.5 mm). Additionally, at 10 mm spacing, a chimney-like effect was observed, enhancing upward air entrainment and resulting in intensified combustion. These findings reveal the coupled influence of geometric configuration and heat transfer mechanisms on façade flame propagation. The insights gained provide guidance for cladding system design, suggesting that increasing lateral separation between combustible elements may be an effective strategy to limit flame spread and enhance fire safety performance in buildings.
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spelling doaj-art-b1ebbb15b2fa4c0493136781c14b16ae2025-08-20T02:45:38ZengMDPI AGFire2571-62552025-07-018728410.3390/fire8070284Experimental Study on Effects of Lateral Spacing on Flame Propagation over Solid Fuel MatrixXin Xu0Yanyan Ma1Guoqing Zhu2Zhen Hu3Yumeng Wang4Jiangsu College of Safety Technology, Xuzhou 221000, ChinaJiangsu College of Safety Technology, Xuzhou 221000, ChinaSchool of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, ChinaJiangsu College of Safety Technology, Xuzhou 221000, ChinaJiangsu College of Safety Technology, Xuzhou 221000, ChinaThe increasing complexity of urban structures has significantly elevated the risk and severity of façade fires in high-rise buildings. Unlike traditional models assuming continuous fuel beds, real-world fire scenarios often involve discrete combustible materials arranged in discrete fuel matrices. This study presents a systematic investigation into the influence of lateral spacing on vertical flame propagation behavior. Laboratory-scale experiments were conducted using vertically oriented polymethyl methacrylate (PMMA) fuel arrays under nine different spacing configurations. Results reveal that lateral spacing plays a critical role in determining flame spread paths and intensities. Specifically, with a vertical spacing fixed at 8 cm, a lateral spacing of 10 mm resulted in rapid flame growth, reaching a peak flame height of approximately 96.5 cm within 450 s after ignition. In contrast, increasing the lateral spacing to 15 mm significantly slowed flame development, achieving a peak flame height of just under 90 cm at approximately 600 s. This notable transition in flame dynamics is closely associated with the critical thermal boundary layer thickness (~11.5 mm). Additionally, at 10 mm spacing, a chimney-like effect was observed, enhancing upward air entrainment and resulting in intensified combustion. These findings reveal the coupled influence of geometric configuration and heat transfer mechanisms on façade flame propagation. The insights gained provide guidance for cladding system design, suggesting that increasing lateral separation between combustible elements may be an effective strategy to limit flame spread and enhance fire safety performance in buildings.https://www.mdpi.com/2571-6255/8/7/284flame spreadheat transferlateral spacingfaçade firesfuel matrix
spellingShingle Xin Xu
Yanyan Ma
Guoqing Zhu
Zhen Hu
Yumeng Wang
Experimental Study on Effects of Lateral Spacing on Flame Propagation over Solid Fuel Matrix
Fire
flame spread
heat transfer
lateral spacing
façade fires
fuel matrix
title Experimental Study on Effects of Lateral Spacing on Flame Propagation over Solid Fuel Matrix
title_full Experimental Study on Effects of Lateral Spacing on Flame Propagation over Solid Fuel Matrix
title_fullStr Experimental Study on Effects of Lateral Spacing on Flame Propagation over Solid Fuel Matrix
title_full_unstemmed Experimental Study on Effects of Lateral Spacing on Flame Propagation over Solid Fuel Matrix
title_short Experimental Study on Effects of Lateral Spacing on Flame Propagation over Solid Fuel Matrix
title_sort experimental study on effects of lateral spacing on flame propagation over solid fuel matrix
topic flame spread
heat transfer
lateral spacing
façade fires
fuel matrix
url https://www.mdpi.com/2571-6255/8/7/284
work_keys_str_mv AT xinxu experimentalstudyoneffectsoflateralspacingonflamepropagationoversolidfuelmatrix
AT yanyanma experimentalstudyoneffectsoflateralspacingonflamepropagationoversolidfuelmatrix
AT guoqingzhu experimentalstudyoneffectsoflateralspacingonflamepropagationoversolidfuelmatrix
AT zhenhu experimentalstudyoneffectsoflateralspacingonflamepropagationoversolidfuelmatrix
AT yumengwang experimentalstudyoneffectsoflateralspacingonflamepropagationoversolidfuelmatrix