A presumed PDF-ILDM model for the CFD-analysis of turbulent combustion (Q979504)

Summary: Today, CFD is a common analysis tool for combustion chambers. A difficult task is still the accurate prediction of minor and intermediate species such as CO. The difficulty arises because the time scales associated to CO production and oxidation are of the same order as the turbulent mixing process, but most turbulent combustion models assume that the chemistry is either very fast or relatively slow in comparison to the time scales of turbulence and mixing. The Intrinsic Low Dimensional Manifold (ILDM) method based on mixture fraction and two reaction progress variables is used to generate an ILDM chemistry table. The method removes fast reactions but includes inter-medium and slow reaction paths. A presumed PDF-ILDM model for turbulent combustion is implemented in the commercial CFD code CFX-5, which models the reaction progress through a reduced set of reaction progress variables. During the CFD analysis all thermo-chemical data is obtained from a pre-integrated chemistry table. A comparison with a partially premixed jet flame shows that the PDF-ILDM model performs much better than other more commonly used combustion models. In particular the good CO predictions are encouraging and indicates the potential of the model for more complex applications.