Experimental Investigation on Formation Mechanism of Jet Fires in Transformer Oil Filled Equipment with External Thermal Load

Abstract

ABSTRACT Liquid jet fire was one of the typical fires that endangered industrial safety. Especially, the oil-filled equipment of the substation was subjected to an external thermal load, which caused liquid jet fire. However, less literature was available for the formation mechanism of liquid jet flame. Thus, this paper conducted a systematic experiment to reveal the formation mechanism of transformer oil jet fire with various heat release rates (33 kW, 73 kW, 132 kW, and 212 kW). In this paper, the formation mechanism of transformer oil jet fire was clarified. Experimental observation showed that the formation process of transformer oil jet fire can be divided into three stages. The gas–liquid two-phase flow occurred during the formation of transformer oil jet fire. The correlation between the overpressure peak and the heat release rate was established. The medium thermal response behavior can be divided into three stages. When the medium temperature reached the boiling point, the jet fire appeared. The thermal stratification model of a transformer oil jet was established. The correlation between the degree of liquid stratification and dimensionless heat release rate was established. The thermal convection and radiation determined the heat transfer mechanism of oil during the formation of jet fire.