A presumed Pdf analysis of partially premixed turbulent combustion

The thermochemistry and chemical kinetics for a partially premixed system in turbulent reacting flows are discussed in terms of activation energy asymptotics and a simple presumed pdf based on two delta functions. The resulting analysis permits fuel and products to coexist, i.e., finite rate kinetic effects are incorporated. Emphasis is placed on lean mixtures since these are of greatest applied interest but the analysis pertains to both rich mixtures and those spanning equivalence ratio of unity. Assessment of the thermochemical model is carried out in two ways, the most comprehensive of which involves the flow in a slender channel. Although the fluid mechanical description of this flow is highly simplified, a large number of parameters are found to be needed to characterize the operative aerothermochemical conditions, the implication being that a wide variety of flows are susceptible to treatment.