Average time of burning

Relative comparison of average burning rate, average time of burning and average extent of burning. 

Values and units Burning rate (mm/min) Average time of burning (s)... 

Example 3.4 A turbulent fire plume is experimentally found to bum with 10 times the required stoichiometric air up to the tip of the flame. It is also measured that 20 % of the chemical energy is radiated to the surroundings from the flame. The fuel is methane, which is supplied at 25 °C and burns in air which is also at 25 °C. Calculate the average temperature of the gases leaving the flame tip. Assume constant and equal specific heats and steady state. 

No explicit mathematical model of the method was presented. However, a short descriptive model was outlined For each run, the average ignition and combustion rate (expressed as weight of fuel ignited or burnt per unit bed area and unit time) were calculated by determining the time taken for the ignition front to pass down through the bed and the completion of burn-out, respectively. No discussion is presented about limitations and assumptions of the method. 

If the propellant grain size averages 1.1 mm, then the average radius (or web size) = 0.55 mm. At a rate of burning of 39.5 mm s the average burning time, Tb, will be given by equation (4.5) ... 

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