燃烧模型对钝体稳燃非预混火焰数值模拟精度的影响

Study on Simulation Accuracy of Combustion Models for Stabilized Non-premixed Bluff-body Flames

为了研究不同燃烧模型在非预混钝体火焰数值计算中的特点,对Sandia实验室HM1火焰进行了数值分析.采用涡耗散概念(EDC)模型、层流小火焰模型和化学平衡模型耦合2种简化机理进行计算,并分别与实验结果进行比较.结果表明:各燃烧模型均能在实验条件下对燃烧过程中的温度场和组分分布等进行正确预测.在使用的3种模型中,层流小火焰模型预测最为精确,且计算速度较快;EDC模型能正确反映变化趋势,但预测所得温度在对称轴附近略高于实验结果;化学平衡模型在燃烧室后部掺混完全的火焰区模拟精度高.层流小火焰模型在研究钝体非预混火焰过程中在计算精度与计算速度方面具有优越性,为进一步进行钝体非预混火焰数值研究奠定了基础.

To investigate the characteristics of different combustion models in predicting the non-premixed bluff-body flame, numerical simulations were conducted on Sandia HM1 flames using eddy dissipation concept （EDC） model, laminar flamelet model and chemical equilibrium model coupled with two different reduced mechanisms, of which the results were compared with experimental measurements. Results show that all the combustion models could predict the temperature field and component distribution under experimental conditions. Among the three combustion models, the laminar flamelet model behaves the best because of its high prediction accuracy and high calculation speed. The EDC model succeeds in predicting the trend but over-predicts the temperature in the near-axis region. The chemical equilibrium model has advantages in predicting fully mixed region in the rear of combustion chamber. Due to its high accuracy and high speed, the laminar flamelet model may serve as a reference for further simulation of non-premixed bluffbody flames.