CH₄/NH₃/空气预混稀燃火焰结构及吹熄特性实验研究

In this experiment，the macrostructure and blow-off characteristics of the compact lean premixed NH₃/air and NH₃/CH₄/air flames stabilized on a bluff-body and swirl burner were studied. Premixed CH₄/air flame was also used for comparison. Particle imaging velocimetry(PIV)and the hydroxyl planar laser-induced fluorescence(OH-PLIF)synchronous measurement techniques were used to capture the flow field and instantaneous OH distribution，and the flame-flow coupling information was obtained. The results show that the flow excessive stretching on the NH₃/air flame surface is the main reason for the local extinguishment and the overall blow-off of the flame. Excessive stretching and local extinction also occur at the root of NH₃/CH₄/air flame near the blow-off，which will lead to the final blow-off of the flame. The main reason for excessive stretching is flow shear deformation. The inner shear layer vortex of the NH₃/air flame will further promote the flame blow-off. Blending CH₄ can greatly improve the extinction strain rate，enhance the stability of lean flame and broaden the lean blow-off limit. At the same time，the addition of CH₄ can also increase the burning velocity and flame temperature，which is conducive to stabilizing the flame.