Reacting Flow in An Aircraft Combustion Chamber

2 Reacting Flow in An Aircraft Combustion Chamber Configuration 

The unstructured mesh is composed of 400,000 nodes and 2,300,000 tetrahedra, which is typical and reasonable for LES of such configuration. The explicit time step is At 0.22 /is. The mesh is refined close to the inlets and in the combustion zone (Fig. 10.3), leading to a flame thickening factor of the order of 10. A one-step chemical scheme fitted to JPlO/air flames is used for chemistry (JPIO is a substitute for kerosene and has the same thermochemical properties). It has been checked that in the simulation the flame mostly burns mixtures with an equivalence ratio in the range between 0.5 and 1, where the chemical scheme is valid. 

First a steady turbulent two-phase flame is calculated. The 15 pm droplet motion follows the carrier phase dynamics so that the Centered Recirculation Zones (CRZ) are similar for gas and liquid, as illustrated on Fig. 10.4, showing the instantaneous backflow lines of both phases, plotted in the vertical central cutting plane. Maintained by this CRZ, the droplets accumulate and the droplet number density, presented with the liquid volume fraction field on Fig. 10.4, rises above its initial value a zone where the droplet number density n is larger than 2n j j (where is its value 

the air velocity must be low enough to match the turbulent flame velocity the dynamics of the carrier phase (and in particular the CRZ) stabilizes the flame front on a stable pocket of hot gases 

zones where the local mixture fraction is within flammability limits must exist combustion occurs between the fuel vapour radially dispersed by the swirl and the ambient air, where the equivalence ratio is low enough 

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