Abstract
The Tatara is the traditional iron-and steelmaking process in Japan. The box type furnace is about 1 m width, 3 m length and 1.2 m height. The process produces steel bloom and pig iron from iron sand and charcoal. The furnace is built on the charcoal bed in a big underground construction which is separated into upper and lower parts by a thick clay layer, "Kobune Kawara". The lower part is a drainage. The upper part has a charcoal bed, "Hondoko", with twin caves, "Kobune", on the both sides. The "Kobune" keeps its temperature lower than 41°C and humidity higher than 89%, that is, 4.8×10-2kg·m-3 in terms of water vapor concentration, during "Tatara" operations. The heat flow and temperature distribution around the furnace during operation was numerically simulated. The water vapor in "Hondoko", hearth and "Doi" flows to "Kobune" according to heat flow and disperses to the surroundings. Further the historical development of underground construction is discussed.
