Experimental study on the combustion characteristics of rectangular fire plumes

This paper presents a comprehensive experimental investigation on the combustion characteristics of rectangular fire plumes. A series of propane fire tests with different aspect ratios, initial heat release rates, and scales are performed. The axial and radial distributions of velocity and temperature as well as the flame length are measured and discussed. The radial distribution and half-width of the axial velocity and temperature all indicate that the fire flow evolves from three- to quasi-two-dimensional as the aspect ratio increases from unity to higher values. In this process, the asymmetric entrainment in the length and width directions of the rectangular fire is verified to play an important role in the flow development. A flame length model is derived, which reasonably well correlates with the data from the current and previous experiments under different aspect ratios, initial heat release rates, and scales. A shape factor extracted from the model can be used as a measure of the aspect ratio effect separately. A dimensionless height coupled with the shape factor well correlates the axial temperature and velocity data under different aspect ratios and initial heat release rates.