Large eddy simulation of the Cambridge/Sandia stratified flame with flamelet-generated manifolds: Effects of non-unity Lewis numbers and stretch

The Cambridge/Sandia turbulent stratified flame (SwB5) is simulated with the LES and Flamelet-Generated Manifolds (FGM) combustion model. Three 3D FGM manifolds are adopted. With the purpose to examine the influence of transport properties, unity and non-unity Lewis numbers ( L e ) are included in the first two manifolds, respectively. The combined effects of non-unity L e and stretch are investigated in the third manifold. Heat loss to the wall is also modeled. Good agreement is found between the simulation and experiment. The equivalence ratio, temperature and mass fractions of CO and H 2 are all well reproduced in contrast with previous simulations. It is found that using non-unity L e can even deteriorate the near-wall temperature modeling. Non-unity L e is proposed to be crucial for the CO prediction as well, besides H 2 . The equivalence ratio modeling is observed to be very important, which accounts for several non-unity L e effects. Flame stretch shows almost no impact on the velocity fields, whereas its effects on the species, equivalence ratio and temperature are identified, although to a limited extent for the Cambridge/Sandia flame.