Due to strict regulations on harmful emissions such as NO_x and CO, many novel combustion techniques have been investigated in order to decrease emissions from gas turbines. One of these novel techniques is colorless distributed combustion (CDC) or flameless combustion (FC). CDC has been examined under reacting conditions using ANSYS Fluent at 27 different operating cases for the aim of developing design equations and a 3D flameless combustion map that includes the effect of air diameter, confinement size and excess air ratio on recirculation ratio to allocate flameless combustion regions. A simple lab scale combustor with central air jet arrangement is employed for the analysis. Eddy dissipation concept (EDC) either global or with detailed mechanism (DRM19) fails to predict the effect of excess air ratio in flameless combustion. A numerical approach for calculating the recirculation ratio is presented. As the air jet diameter decrease 40% there is about 54% increase in the recirculation ratio and about 90% decrease in the NO_x emissions. It is found that above a recirculation ratio of 3 there is an insignificant effect on NO_x emissions. Reducing the combustor diameter by a constant value for a given air diameter is found to result in a decrease in the recirculation ratio and the percentage of decrease is higher at high thermal intensities combustors. Moreover, it is observed that as the combustor diameter decrease to half of its value at constant air jet diameter and constant excess air ratio, there is an 80–90% increase in the NO_x emissions inside the combustor. Furthermore, design equation is obtained to predict the appropriate air diameter that if combined with the available combustor diameter achieves a minimum recirculation ratio suitable to sustain flameless combustion.

由于对有害气体的排放严格的规定，如NO _X为了减少燃气轮机的排放，已经研究了许多新颖的燃烧技术。这些新技术之一是无色分布燃烧（CDC）或无焰燃烧（FC）。为了开发设计方程式和3D无焰燃烧图，包括在反应条件下使用ANSYS Fluent在CDN的反应条件下对CDC进行了检查，该图包括空气直径，限制尺寸和过量空气比对再循环比的影响，以分配无焰燃烧区域。使用带有中央空气喷嘴装置的简单实验室规模燃烧器进行分析。整体或具有详细机理的涡流消散概念（EDC）（DRM19）无法预测无空气燃烧中过量空气比率的影响。提出了一种计算再循环比的数值方法。_x排放量。已经发现，在再循环比为3以上时，对NO _x排放没有显着影响。对于给定的空气直径，将燃烧器直径减小恒定值会导致再循环率降低，并且在高热强度燃烧器中，减小百分比更高。此外，可以观察到，随着燃烧器直径减小到其值的一半在恒定的空气射流直径和恒定的空气过剩率，有在NO的增加80-90％_X燃烧器内的排放。此外，获得设计方程以预测适当的空气直径，如果与可用的燃烧器直径结合使用，则可获得适合于维持无焰燃烧的最小再循环率。