Numerical Simulation Of Effects Of Inhibition Additives In Turbulence Diffusion Flame With Cmc Method

The numerical study of effects of inhibition additives in turbulent combustion is significant for understanding of inhibition mechanism and development of high efficiency inhibitor. Firstly, the numerical simulation of turbulent combustion itself is a complex job. Many scientists were dedicated to study this problem around the world. The conditional moment closure(CMC) model was one of accurate models which is derived by Bilger and Klimenko in the 1990s, and it became one of the most popular combustion models with PDF model and LFM(Laminar flamelet model). The main hypothesis of CMC is that most of the fluctuation in the reaction scalar quantities can often be associated with the fluctuation of mixture fraction which is a conserved scalar. It closes the reaction source term on first order moment.On the other hand, a worldwide ban on the production of the principal halogenated fire suppressants has created a need for new, environmentally acceptable fire suppressants. In particular, iron pentacarbonyl was found to be one of the strongest inhibitors. Many researches about it were conducted recent years home and abroad. However most of these researches were on the condition of experiments and laminar combustion simulation, thus there are less systematic studies in turbulent combustion.This paper firstly analysis CMC models in detail and design iteration algorithm. The results from CMC were compared with Sandia H₂/He flame experiments, which were applied to build a more accurate CMC simulation platform. Then the reduced inhibition mechanism of Fe(OH)₂ was coupled by the platform. The result shows that the additive made more inhibition effects on H, O and OH in turbulent diffusion flame (H:90%,O:30%,OH:25%) than laminar diffusion flame (H:50%,O:15%,OH:10%). which is caused by turbulence diffusion effects. The results of Damkholer number shows that the inhibitor makes flame more unstable. The position of steady combustion extends 3D along the axial position. (D is nozzle diameter.)The idea of suppression agent surrogate was bring in turbulent diffusion flame, which can be applied to analysis the efficiency ratio of surrogate that represent some aspects of suppression agent. Opposed flame model of CHEMKIN was applied to analysis the efficiency ratio in laminar diffusion flame. The data show this parameter is 70% in laminar diffusion flame and 95% in turbulent diffusion flame.