针对天然气在O2/N2氛围下扩散燃烧时，过量空气系数和旋流数对WNS型燃气锅炉燃烧室内的温度分布、速度分布及NOx生成的影响，利用CFD软件，采用标准k-ε湍流模型、P-1辐射模型和涡耗散模型进行数值模拟。基于旋流对流动特性的影响，采用旋流数S来表示入口空气的旋流强度。结果表明：在过量空气系数α从1.0增大到1.3的过程中，火焰直径逐渐变小，排烟温度降低，燃烧室出口处NOx的质量分数逐渐减小；在空气旋流数从0提高到0.8的过程中，燃烧室内形成了中心回流区，火焰的径向流动分布逐渐改善，燃烧室内的温度分布更加均匀；旋流燃烧的火焰中心轴线温度分布高于直流射流燃烧，提高空气旋流数可以有效降低NOx的质量分数。

The effects of excess air coefficient and swirl number on temperature distribution, velocity distribution and NOx generation in the combustion chamber of WNS gas boiler when natural gas diffused and burned in O2/N2 atmosphere were addressed. The numerical simulations were carried out by using CFD software, the standard k-ε turbulence model, P-1 radiation model and eddy dissipation model. Based on the swirling effect on dynamic flow behavior, the swirl number S was used to express the swirling intensity of the inlet air. The results show that in the process of increasing the excess air coefficient α from 1.0 to 1.3, the diameter of the flame gradually decreases, the exhaust gas temperature decreases, and the mass fraction of NOx at the outlet of the combustion chamber gradually decreases; in the process of increasing the number of air swirls from 0 to 0.8, a central recirculation zone is formed in the combustion chamber, the radial flow distribution of the flame is gradually improved, and the temperature distribution in the combustion chamber is more uniform; the temperature distribution of the central axis of the swirling combustion flame is higher than that of the straightflow jet combustion, and increasing air swirl number can effectively reduce NOx mass fraction.

TK16

国家自然科学基金青年基金项目(51906164)