Multiplication of hydroxyl and formaldehyde planar laser-induced fluorescence signals for turbulent hydrogen-enriched methane–air flames with compositionally inhomogeneous mixtures is investigated experimentally. Hydrogen-enriched methane–air flames with a global fuel–air equivalence ratio of 0.8 and hydrogen-enrichment percentage of 60% are examined. Two nozzles, each containing 4 fuel/air injection lobes are used in the experiments. The lobes of the first nozzle are straight, while those of the second nozzle are not, generating a swirling motion. The fuel is injected through several small diameter holes into the lobes. The amount of injected fuel flow rate varies between the lobes, generating stratified conditions. For each nozzle, two mean bulk flow velocities of 5 and 25 m/s are tested. Simultaneous hydroxyl and formaldehyde planar laser-induced fluorescence as well as separate stereoscopic particle image velocimetry are performed for the tested reacting conditions. For non-reacting flow tests, separate particle image velocimetry and acetone planar laser-induced fluorescence experiments are conducted to study the background turbulent flow characteristics and fuel/air mixing, respectively. The results show that stratification can lead to fragmentation of the flames and generation of islands with noticeable multiplication of hydroxyl and formaldehyde planar laser-induced fluorescence signals. Due to their significantly large number of occurrences, such flame structure can generate relatively large integral of the PLIF signals multiplication.

实验研究了羟基和甲醛平面激光诱导的湍流富氢甲烷-空气火焰与成分不均匀混合物的荧光信号的相乘。研究了全球燃料-空气当量比为0.8，氢富集百分比为60％的富氢甲烷-空气火焰。实验中使用了两个喷嘴，每个喷嘴包含4个燃料/空气喷射瓣。第一喷嘴的凸角是笔直的，而第二喷嘴的凸角不是笔直的，从而产生涡旋运动。燃料通过几个小直径的孔注入到叶片中。喷射的燃料流量的量在波瓣之间变化，从而产生分层条件。对于每个喷嘴，测试了5和25 m / s的两个平均总体流速。对于测试的反应条件，同时进行了羟基和甲醛平面激光诱导的荧光以及单独的立体粒子图像测速。对于非反应性流量测试，分别进行了颗粒图像测速和丙酮平面激光诱导的荧光实验，分别研究了背景湍流特性和燃料/空气混合。结果表明，分层可导致火焰破裂并产生岛状结构，其中羟基和甲醛平面激光诱导的荧光信号显着增加。由于它们大量出现，这种火焰结构会产生相对较大的PLIF信号乘法积分。