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对燃料-空气非预混、完全预混与部分预混三种混合模式下的无焰燃烧状态进行了实验和数值模拟研究。采用了详细化学反应机理和已被实验验证的算法进行数值模拟。研究发现三种混合模式下无焰燃烧状态的区别是由初始反应物的射流总动量的不同决定的。当炉内大尺度流场结构类似时,初始反应物射流总动量越大,炉内烟气循环越剧烈,温度分布越均匀,峰值温度越低,NO_x越低。数值模拟发现OH自由基峰值位置与温度峰值位置基本重合;而H_2CO峰值位置主要分布在主反应区中的低温区域。实验测量了当量比对无焰燃烧炉内温度和NO_x排放值的影响,并发现部分实验还发现,部分预混、非预混和完全预混无焰燃烧时,NO占NO_x总量的百分比分别为94.3%、91.9%和76.9%。
Experiments and numerical simulations of flameless combustion in three mixed modes of fuel-air non-premixed, fully premixed and partially premixed were carried out. Using a detailed chemical reaction mechanism and has been experimentally validated algorithm for numerical simulation. It is found that the difference between flameless combustion states of the three mixed modes is determined by the difference of the total jet momentum of the initial reactants. When the structure of the large-scale flow field in the furnace is similar, the total momentum of the initial reactant jet is larger, the flue gas circulation in the furnace is more intense, the temperature distribution is more uniform, and the lower the peak temperature, the lower the NO_x. The numerical simulation shows that the peak position of OH radical basically coincides with the peak temperature, while the peak position of H 2 CO mainly distributes in the low temperature region of the main reaction zone. The effect of equivalence ratio on the temperature and NO_x emission in a flameless combustion furnace was measured. Some experiments also found that the percentages of NO and NO_x in the partial pre-mixing, non-premixing and premixed non-flaming combustion were 94.3%, 91.9% and 76.9%.