Temperature gradient in the gas phase

As shown in Fig. 5.25, the temperature gradient in the gas phase at Tq = 243 K and p = 3 MPa reaches a maximum at the burning surface, decreases with distance from the burning surface, and becomes zero at a distance of about 1.1 mm. When the initial temperature, Tq, is increased from 243 K to 343 K, the temperature gradient is increased and becomes zero at about 0.7 mm from the burning surface. 

The heat flux transferred back from the gas phase to the burning surface is dependent on the temperature gradient in the gas phase, which is inversely proportional to the thickness of the reaction zone in the gas phase. Since the reaction in the gas phase is complete at the upper end of the bluish flame, the heat flux defined by Am conforms to the proportionality relationship Am l/6g p0- . The observed pressure dependence of the burning rate, is caused by the pressure depend-... 

Fig. 7.28 Temperature gradients in the gas phase just above the burning surfaces of non-catalyzed and 0.5% LiF-catalyzed AP composite propellants.

The boron particles are thermally inert in the solid phase beneath the burning surface of the pyrolant The oxidation of the boron particles occurs just above the burning surface. This implies that the temperature gradient in the gas phase, (j), increases and hence the burning rate is increased accordingly. 

From Equation 22, the temperature gradient in the gas phase at the droplet surface is ... 

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