H. Karim et al., COMPUTATIONAL COMPARISON BETWEEN AN ELLIPTIC AND A BOUNDARY-LAYER FORMULATION FOR METHANE AIR COMBUSTION ABOVE A HEATED NONCATALYTIC SURFACE/, Combustion science and technology, 119(1-6), 1996, pp. 107-130
A fully two-dimensional elliptic model with a detailed gas phase react
ion mechanism for the combustion of premixed fuel (CH4) and air, over
a non-catalytic, non-permeable plate is presented. By comparing soluti
ons for ignition distances and species profiles predicted by the ellip
tic and boundary layer models, a criteria, based on the equivalence ra
tio and the wall temperature was obtained, which can be used to determ
ine when the boundary layer approximation is valid. For low equilvalen
ce ratios (phi < 0.4), no difference (except in the vicinity of the le
ading edge) was observed between the predictions of the two models at
downstream distances from the leading edge of the plate for wall tempe
ratures up to 1580 K. For high equivalence ratios (phi greater than or
equal to 0.4) and for wall temperatures above 1300 K, the predictions
differed significantly. The boundary layer model always predicted a t
hicker reaction zone.