Experimental Study of Combustion Characteristics of Circular Ring Thin-Layer Pool Fire

For clarifying the combustion behavior of a circular ring thin-layer pool fire, a series of experiments with varying pool diameters were carried out. The equivalent pool area of 0.071 m2 and an initial n-heptane thickness of 10 mm were fixed. An electronic balance, a digital camera, and K-type thermocouples were used to measure burning rate, flame height, and centerline temperature, respectively. The results show that more burning stages can appear with the increase of the inner and outer diameters of the circular ring pool. Fire merging can occur at any one of the stages of initial growth, quasi-steady burning with surface boiling, transition to bulk boiling, and bulk boiling burning; moreover, the maximum burning rate of fire merging is about 3.5 times that of the ordinary pool fire with the same area. The core hollow region plays an important role in decreasing the burning rate, flame height, fire merging time, etc. The evolutions of the characteristic parameters, e.g., burning rate, flame height, and centerline temperature, were analyzed. New correlations for predicting these parameters were also proposed.