Experimental and analytical study on inclined turbulent fire in still air. Part 2. Round fire

This paper reports an experimental and analytical study on non-vertical round turbulent jet fire. A series of propane jet fire tests are performed under different initial flame angles ( & theta;0 ) and initial fuel velocities. The two-dimensional velocity and temperature fields of the flame are measured, and the flame geometry is determined from video images. Experimental results show that the flame entrainment is enhanced as & theta;0 decreases. The flame deflection-induced buoyancy flow plays an essential role in the local flame structure and turbulence. A model of round fire combined with a kinetic energy equation is established, in which the flame entrainment coefficient is analytically correlated with the buoyancy and streamline curvature. Model calculations reproduce the flame entrainment and flame trajectory, consistent with the experimental indications. Under the same burner area and heat release rate, the entrainment coefficient of round fire is greater than that of line fire, closely associated with the difference in integral buoyancy triggered by different burner geometries. The results of this paper may help understand the flame motion and predict the flame radiation of turbulent & COPY; 2022 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

This paper presents an experimental and analytical study on non-vertical round turbulent jet fire. Propane jet fire tests are conducted to measure the velocity and temperature fields of the flame, as well as determine its geometry from video images. The results show that flame entrainment is enhanced as the initial flame angle decreases, and flame deflection-induced buoyancy flow significantly influences the flame structure. A model combining a kinetic energy equation is established to analytically correlate the flame entrainment coefficient with buoyancy and streamline curvature, and the model calculations are consistent with the experimental indications. The study provides insights into flame motion and flame radiation prediction in turbulent conditions.