Experimental research into the behavior of ventilation air around shafts during a fire

Inoue, Masahiro*; Hidaka, Yuki*; Yamakami, Mitsunori; Hatakeyama, Nobuya; Okuzono, Akihiko*; Sakai, Tetsuo*

A series of experimental study using a scaled model concerning the behavior of ventilation air during a mine fire was carried out. The model consists of two vertical shafts, three horizontal ducts and a exhaust fan. The cross section of the shaft and duct is 0.2m square. The height of the shafts is 3.4m. The length of the ducts is 1.5m. The airflow rate can be adjusted by regulators installed in each duct. The behavior of the fire gas was measured by anemometer, thermometer, and visualized image using laser light. Some amount of fire gas of high temperature rose upward gradually along the shaft wall regardless of the downward ventilation. Then the direction of main ventilation air suddenly reversed upward in the shaft. The direction of ventilation reversed in many places in the model and the fire gas reached even the part not anticipated. It was also found that the direction of ventilation in the shaft reversed upward entirely when the initial velocity of the airflow was small.