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运用数值方法对U型燃烧室内天然气高温空气燃烧进行研究,其中湍流流动采用雷诺应力模型,燃烧采用涡团耗散模型,耦合辐射传热模型;NO生成考虑了热力型NO生成机制和快速反应NO生成机制。其数值计算结果与相应实验结果吻合较好。分析了助燃空气温度、过量空气系数、助燃空气中氧浓度对燃烧特性的影响。研究表明:随着助燃空气温度增加,燃烧室气体温度升高,壁面平均热流和出口NO浓度增大;随着过量空气系数的增加,燃烧的最高温度和NO排放增加,气体平均温度及热流密度先增加后减小,过量空气系数为1.2时温度均匀性好,传热量最大;随助燃空气中氧浓度减小燃烧室温度均匀性增强,壁面平均热流增大,NO生成量显著减小。
The numerical method was used to study the combustion of natural gas at high temperature in a U-shaped combustion chamber. The turbulent flow was dominated by the Reynolds stress model, and the eddy dissipation model and the coupled radiation heat transfer model were used for the turbulent flow. The NO generation took into account the generation mechanism of the thermal NO and the rapid response NO Generate mechanism. The numerical results agree well with the corresponding experimental results. The effects of combustion air temperature, excess air ratio and oxygen concentration in combustion air on combustion characteristics were analyzed. The results show that as the combustion air temperature increases, the combustion chamber gas temperature increases, the average wall heat flow and outlet NO concentration increase; with the increase of excess air coefficient, the maximum combustion temperature and NO emissions increase, the average gas temperature and heat flux First increase and then decrease, when the excess air ratio is 1.2, the temperature uniformity is good and the heat transfer is the largest. With the decrease of oxygen concentration in combustion air, the uniformity of combustion chamber temperature increases and the average heat flow increases, the NO generation decreases significantly.