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通过雷诺平均纳维叶斯托克斯方程模型数值模拟研究了同流热气中氧浓度对CH4/H2射流火焰扩散燃烧的影响。研究基于JHC开放火焰实验装置,采用涡耗散概念模型和GRI-3.0详细化学反应机制进行数值模拟,研究同流热气中氧浓度变化的影响。结果显示,随着同流热气中氧浓度的减小,下游温度峰值及中间组分OH的质量分数峰值明显下降,温度分布更均匀。OH质量分数峰值位置比温度峰值位置略微靠外(同流热气侧)。H2CO主要分布在计算域内的低温区,高温时该组分被快速消耗;不同的燃烧模式下H2CO浓度分布差别很大。通过分析发现,要使传统窄小区域的快速燃烧模式过渡到大空间的慢速弥散燃烧,应减小同流热气中氧浓度。
The effect of oxygen concentration in the same flow on the flame diffusion combustion of CH4 / H2 jet was studied by Reynolds-averaged Navier-Stokes equations. Based on the JHC open flames experimental apparatus, the numerical simulation of the vortex dissipation conceptual model and the GRI-3.0 detailed chemical reaction mechanism were carried out to study the influence of oxygen concentration in the same-stream hot gas. The results show that with the reduction of oxygen concentration in the hot gas in the same stream, the peaks of the downstream temperature and the OH content of the middle fraction obviously decrease and the temperature distribution is more uniform. OH peak position slightly higher than the temperature peak position (reheat hot side). H2CO is mainly distributed in the low temperature region of the calculation domain, and the component is rapidly consumed at high temperature; the distribution of H2CO concentration varies greatly under different combustion modes. Through the analysis, we found that in order to make the transition from the fast combustion mode in the traditional narrow area to the slow dispersion combustion in the large space, the oxygen concentration in the hot gas should be reduced.