Experimental study of the effectiveness of a water mist segment system in blocking fire-induced smoke and heat in mid-scale tunnel tests

摘要

A 1/3-scale model tunnel installed with a water mist segment system is built to study the effectiveness of a water mist segment system in blocking fire-induced smoke and heat. Interaction of water with fire is avoided. A series of 14 tests are performed for a wide range of settings, including variable fire loads, nozzle quantities, water pressures and longitudinal ventilation velocities. Temperature distribution is presented and discussed for different ventilation conditions. A method for qualitatively analyzing the effectiveness of the water mist segment in blocking fire-induced smoke and heat is proposed, and the smoke blocking phenomenon resulting from the water mist segment system is discussed and explained by an order of magnitude analysis. Important parameters, including the total water flow rate (nozzle numbers), water pressure, heat release rate, and the distance from fire source to the water mist segment, are suggested for improving the smoke blocking efficiency of water mist segment systems in tunnels. The effects of the water mist segment on life safety are discussed at last.