<p>A series of fire experiments in a 1/10 scale model tunnel with a lateral open shaft were conducted. Analysis was performed to explore the maximum excess temperature and longitudinal temperature decay under the influence of a mechanical exhaust system with a lateral open shaft. Three different pool sizes and numerous extraction rates were considered. The experimental results yielded intriguing insights into the correlations between the rate of smoke extraction and the ceiling temperature. The variations in the temperature distribution of ceiling smoke upstream and downstream the fire source is different under the induced longitudinal velocity, especially for the near the fire source area. An analysis of the maximum excess temperature was conducted by inducing the heat loss coefficient <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41598_2024_79576_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="12" /> </InlineMediaObject> <EquationSource Format="TEX">\(\delta\)</EquationSource> </InlineEquation>. It is 0.85 (0.71) for the induced dimensionless longitudinal velocity <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41598_2024_79576_Article_IEq2.gif" Format="GIF" Height="18" Rendition="HTML" Resolution="72" Type="Linedraw" Width="83" /> </InlineMediaObject> <EquationSource Format="TEX">\({\lambda V_{s} }^{\prime} \le 0.19\)</EquationSource> </InlineEquation> <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41598_2024_79576_Article_IEq3.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="110" /> </InlineMediaObject> <EquationSource Format="TEX">\(\left( {\left( {\lambda V_{s} } \right){\prime}> 0.19} \right)\)</EquationSource> </InlineEquation>, which indicates the effect of a large velocity on the smoke heat loss. Then, a modified model of the maximum excess temperature was given for a tunnel utilizing lateral open shaft smoke extraction. In addition, a simple model was proposed to capture ceiling temperature decay, where the decay coefficients <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41598_2024_79576_Article_IEq4.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="16" /> </InlineMediaObject> <EquationSource Format="TEX">\(k_{i}\)</EquationSource> </InlineEquation> upstream and downstream of the fire source are proportional to <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41598_2024_79576_Article_IEq5.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="52" /> </InlineMediaObject> <EquationSource Format="TEX">\(1/Q^{^{\prime}1/3}\)</EquationSource> </InlineEquation>(<InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41598_2024_79576_Article_IEq6.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="70" /> </InlineMediaObject> <EquationSource Format="TEX">\(V_{in}{\prime} /Q^{^{\prime}1/3}\)</EquationSource> </InlineEquation>) for <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41598_2024_79576_Article_IEq7.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="95" /> </InlineMediaObject> <EquationSource Format="TEX">\(( {\lambda V_{s} })^ {\prime} \le 0.19\)</EquationSource> </InlineEquation><InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41598_2024_79576_Article_IEq8.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="110" /> </InlineMediaObject> <EquationSource Format="TEX">\(\left( {\left( {\lambda V_{s} } \right){\prime}> 0.19} \right)\)</EquationSource> </InlineEquation>. The research results have certain guiding significance for the arrangement of fire protection, fire monitoring and early warning devices in mountain tunnels.</p>

Experimental and theoretical study on ceiling temperature distributions in mountain tunnel with a lateral open shaft

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2025年1月2日

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Yuchun Zhang,
Xinyu Liu,
Rui Tan,
Wei Hou,
Longfei Chen,
Shaoshuai Xing,
Zhisheng Li,
Yunhai Guo,
Xiaoqing Han

摘要

A series of fire experiments in a 1/10 scale model tunnel with a lateral open shaft were conducted. Analysis was performed to explore the maximum excess temperature and longitudinal temperature decay under the influence of a mechanical exhaust system with a lateral open shaft. Three different pool sizes and numerous extraction rates were considered. The experimental results yielded intriguing insights into the correlations between the rate of smoke extraction and the ceiling temperature. The variations in the temperature distribution of ceiling smoke upstream and downstream the fire source is different under the induced longitudinal velocity, especially for the near the fire source area. An analysis of the maximum excess temperature was conducted by inducing the heat loss coefficient \(\delta\) . It is 0.85 (0.71) for the induced dimensionless longitudinal velocity \({\lambda V_{s} }^{\prime} \le 0.19\) \(\left( {\left( {\lambda V_{s} } \right){\prime}> 0.19} \right)\) , which indicates the effect of a large velocity on the smoke heat loss. Then, a modified model of the maximum excess temperature was given for a tunnel utilizing lateral open shaft smoke extraction. In addition, a simple model was proposed to capture ceiling temperature decay, where the decay coefficients \(k_{i}\) upstream and downstream of the fire source are proportional to \(1/Q^{^{\prime}1/3}\) ( \(V_{in}{\prime} /Q^{^{\prime}1/3}\) ) for \(( {\lambda V_{s} })^ {\prime} \le 0.19\) \(\left( {\left( {\lambda V_{s} } \right){\prime}> 0.19} \right)\) . The research results have certain guiding significance for the arrangement of fire protection, fire monitoring and early warning devices in mountain tunnels.