The impact of the upwind angle for a wind-driven iron smelting furnace in Sri Lanka

Sri Lanka was the world's leading iron exporter around 3000BC. In 1990, the Samanalawewa archaeological survey identified forty one ancient iron smelting furnaces positioned along the western edge of the foothills and driven by natural draught. These furnaces functioned by heating the air within them thus reducing its density and causing it to rise. Unheated air was then drawn to the furnace through tuyeres. Ideally the natural draft can create high airflow rates if the resistance within the furnace is low. Therefore it is important that the furnace design-parameters are optimized to facilitate the combustion process to produce both low-carbon bloomery iron and high-carbon steel. The upwind angle generally depicts the wind direction and its impact in turn decides the tuyer parameters. The objective of this study was to quantify the effect of parameters for published data using statistical methods and, to analyze the cold flow of 2D geometry using CFD at steady state conditions for different upwind angles in OpenFOAM software. The simulation results indicated that the mean velocity across the furnace increases with the angle and the combined effect of the upwind angle and wind speed significantly affect the flow rate through the furnace.