On Modeling of Quenching Phenomena by Numerical Data of Counterflow Diffusion Flames.

Abstract

With a mind to develop a model capable of dealing with the turbulent combustion with the local extinction, flame stuctures with the local extinction have been numerically investigated in the counterflow configuration. The mass, momentum, species, and energy conservation equations were solved by the SIMPLE algorithm to seek steady state solutions. A Lewis number of unity and a one-step irreversible reaction with a finite rate were assumed. To describe flame tip structure, a reaction progress variable based on the amount of a product is introduced in addition to the mixture fraction and the scalar dissipation rate. It is found that the flame tip structure is divided into three categories; say, the fully burnt flamelet, the intermediate flamelet, and the preheat region and is determined by the above three parameters at an accuracy level. Especially, the first two of flame structures are uniquely determined by the three parameters; however, the last one has revealed a small deviation attributable to the diffusion process. However, so long as the scalar structure of the preheat region is kept to be similar to the flame structure, the three parameters are important factors determining the flame tip structure.