k-ε-g紊流燃烧模型数值研究

NUMERICAL ANALYSIS OF k-ε-g TURBULENT COMBUSTION MODEL

关键词:  紊流燃烧  模型  数值分析

Key words:  Turbulent combustionj Model  Numerical analysis

摘要:

本文对k-ε-g紊流燃烧模型中模型系数C_R,C_g1,C_g2的选定和计算浓度脉动均方值g的不同方法进行数值研究。计算结果表明模型系数值的选定直接与化学反应速率有关,而其中C_R影响最大。g的计算虽然可有不同方法,而其中微分方程求解最佳。并用实验数据来验证计算结果。

Abstract:

The k-ε-g turbulent combustion model is widely applied to many combustion systems by using model coefficients* which are different for various investigators. It fact, it is very important for better modelling combustion process to determine model coefficients Cg1, Cg2, CR and mean square fluctuation of fuel concentration g. Calculations and experiments of combustion recirculating flow behind flame-holders are conducted. Predicted profiles of flow parameters are obtained by using different values of model coefficients and expressions of g. Experiments on gas temperature and combustion efficiency are preformed in a simulated afterburner with bluff-body flame-holders. Good agreement of predicted values with experimental data shows that model coefficients are closely related to reaction rate. Among them, the influence of CR is significant. An expression of CR, which accounts for the effect of temperature, is proposed, g obtained from solving g differential equation is more rational than its algebric expression used for given initial value. The coefficients appearing in transport terms are relatedby Cgt=2/σf and cg2=2.0.