摘要
贫预混燃烧中的混合问题对深入理解污染物排放机制至关重要。本文针对某一特定喷嘴进行混合特性实验测量,通过三维数值模拟与实验测量值进行比较,分析得出湍流施密特数对混合特性的影响,发现施密特数为0.5时数值模拟结果与实验值符合良好;随后依据实验值和三维数值模拟结果,并结合理论分析混合分数方差控制方程中扩散项和生成项所占比例,提出用于衡量燃机预混燃烧混合特性的一维混合模型。结果显示,该特定喷嘴的混合效果很好;混合分数方差控制方程中的扩散项和生成项所占比例不超过25%,一维模型能依据有限实验值较好地预测燃烧室中的混合不均匀度。
The mixing process in lean premixed combustion is of vital importance for the pollutant emission. In this study, according to comparison of the 3D simulations and the mixing experiments based on a specific nozzle, the effects of Turbulent Schmidt number on the characteristics of mixing were analyzed, and it was observed that with Sc=0.5, the results from simulations had a good agreement with the experimental data. In terms of the results of simulations and experiments, a 1D model for the prediction of unmixedness was proposed based on the analysis of the proportion of the diffusion and production terms in the governing equation for the variance of mixture frac- tion. It is shown that the specific nozzle can achieve pretty good mixing characteristics. With the analysis of the governing equation for the variance of mixture fraction, it was found that the diffusion and production terms only accounted for less than 25% of the total variance, and the 1D model was able to predict the unmixedness in the combustor of gas turbine according to limited experimental data.
出处
《工程热物理学报》
EI
CAS
CSCD
北大核心
2017年第11期2461-2466,共6页
Journal of Engineering Thermophysics
基金
国家自然科学基金资助项目(No.51476087)
清华大学燃机自主科研项目(No.2014z9912)
关键词
低排放
混合
一维混合模型
low emission
mixing process
1D mixing model
