Study of smoke spread length in single-side exhaust mode tunnel
To study the smoke flow characteristics of single-side centralized smoke exhaust mode in tunnel fire,the influence of heat release rate and smoke exhaust volume on the smoke spread length in a single-side centralized smoke exhaust tunnel is investigated in this paper.This article uses a 1:20 reduced-scale model test method,a gas ignition system to adjust the heat release rate of the fire source,a smoke exhaust system to adjust the smoke exhaust rate,a temperature measurement system,and a flow rate measurement system to collect real-time data.Quantitative analysis is subsequently implemented,concerning the change rules of the longitudinal temperature of the tunnel in the single-side exhaust mode under the influence of different heat release rates and smoke exhaust rates.The smoke spread length is accessed according to the temperature field under varied fire conditions.Through literature research and theoretical analysis,the relationship among heat release rate,smoke exhaust volume,and smoke spread length is explored,and the mathematical prediction model of smoke spread length under single-side centralized smoke exhaust mode is established.The results show that under the single-side centralized smoke exhaust mode,the temperature field is asymmetrically distributed,and due to the gas flow in the tunnel lane of the fan side is less than that of the closed side,the smoke spread length near the side of the exhaust fan is larger than that on the closed side;the smoke spread length upstream and downstream of the fire source increases with the increase of the heat release rate,and decreases with the increase of smoke exhaust volume;through optimizing the prediction model of smoke spread length under longitudinal ventilation,a prediction model for smoke spread length upstream and downstream of the fire source under the single-side centralized smoke exhaust mode is obtained,and the predicted value of the prediction model can describe the experimental value well.
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