A numerical method for reacting flows with multi-step, stiff chemical kinetics

Abstract

A numerical method has been developed to solve reacting flow systems with multi-step, stiff chemical kinetics. The advantage of this new method lies in the unique approach to the solution of species conservation equations, while the flow field is obtained in the conventional pressure-velocity coupling fashion, such as SIMPLEC. Unlike the widely-used operator-splitting method, in which the species solution is realized by the local ODE integration of chemistry and subsequent solution of flow transport equations, this new method for species solution distinguishes itself by 1) a full species Jacobian mahix to linearize the stiff chemical source terms, 2) efficient solver for both spatially and species-wise coupled discrete system of species conservation equations. Being free from the extremely CPU-time-consuming ODE integration and the inconsistency incurred frm operator-splitting. this new approach appears much more attractive for its compumtiod efficiency and better accuracy. A series of reacting flow cases, encompassing low and high speed flames with a variety of combustion kinetics, were simulated and compared with available data to demonstrate the accuracy and robustness of this method. NOMENCLATURE Aj pre-exponential factor of Arrhenius Anb A, formulation link coefficient for neighboring cells link coefficient for current cell forwardheverse exponent of species concentration i in reaction j hoject Engineer, Member AIAA