Experimental Studies On Flame And Combustion Characteristics Of Fire Whirlwind

Firewhirl is complex combustion behavior occurring often in forest and urban fires. It contains physical and chemical reactions and shows particular dynamic characteristics with special vortex flow. The current research was focused on theoretical analysis and computer simulation. It's difficult to find test data due to rare experimental studies.Based on the large-scale experimental table we performed firewhirl with different diameters. To study the combustion characteristics of the firewhirl, experimental measurement of the main properties of the combustion was measured, including mass loss rate, flame height, flame temperature field, wind speed and radiant heat flux, obtaining a mass of data under laboratory conditions. The analysis showed there are great differences between the firewhirl and pool fires. The flame of firewhirl is cylindrical and the flame height is greater than the diameter, in comparison to pool fires, the firewhirl has stronger entrainment and higher temperature, more special phenomenon is the fire wandering. These interesting characteristics reveal the laws of the firewhirl.Analyzing the experimental parameters changing with the diameters we found that when the diameter increases, the mass loss rate per unit area, maximized and Zukoski height also increase, and there is relationship between them. The average flame temperature increases with height first and then decrease, the temperature distribution not only reflects the combustion intensity throughout the flame, it also tells the flame's appearance. A large number of temperature data shows the temperature expression in the continuous flame, intermittent region and plume region of the firewhirl. The continuous flame height is high compared to the maximized flame height and the experimental data reveals the similarity between different diameters firewhirl.There are some computer simulations about the internal flow of firewhirl without experimental verification, air velocity at air inlet point out the entrainment of firewhirl in the middle of the flame is greater than that in the bottom and top, so does the upward velocity.