1. The length ofthe induction zone varies from 6000 um fora pressure of 50 bars up to 20000 for 10 bars. Consequently, the secondary flame is located quite far from the surface in comparison with the 100 um of the primary flame thickness. Insuch a condition it is straightforward toassure that the heat flux coming from the secondary flame is negligible in comparisonwiththe oneduetothe primary flame, despite the fact, that the secondary flame temperature is much higher (Tfsec= 2700 K, Tfpri = 1650 K). Then, that the burning rate is rather dependent on the primary flame heatfeedback tothe solid.
2. Consideringthe resultsobtained bythe Office National Etudes et de Recherche Aerospatiale (ONERA France) (Table I)20andothers 22-24^wemustobtain:
3. m" -Psol Vc- pyrolysis massflow rate psol = solid propellantdensity (1650kg.m-3) Vc = solid propellantburningrate Di = moleculardiffusion coefficient ofthe specy i toi = production rateofthe specy i The diffusion coefficients mustbe verified the conditions:
4. m" = 1.210-3psolP0.48 2) Far from the wall -> equilibrium state: