Measurements and modeling of the laminar flame speeds of n-propyl and 1,3,5-trimethyl benzenes at moderate pressures

Aromatics are major components of real and surrogate jet fuels and can produce rich stabilized radicals to inhibit the mixture reativity. The laminar flame speeds of the two aromatic C9H12 isomers, n-Propylbenzene and 1,3,5-TriMethyl benzene are measured at atmospheric pressure. A kinetic model have been developed, and tested against these new experimental data as well as against previously published data. Both experiments and computations show that n-Propylbenzene exhibits higher flame speeds than the other isomer, due to the weaker bonds in the propyl side chain. The increase of pressure results in an increased inhibitive effect on the flame velocities for both fuels because of the competition between the two reactions H+O₂=O+OH and H+O ₂(+M)=HO₂(+M). The oxidation pathway of the 1,3,5-triMethyl benzene isomer has been delineated and is computed to be little sensitive to the pressure. However, results show that the degradation scheme of n-Propyl benzene is observed to be more strongly pressure dependent.