受限空间预混钝体稳定与抬升火焰激光诊断

在受限空间预混钝体燃烧器中，利用OH-PLIF （平面激光诱导荧光）、PIV （粒子图像测速）和瑞利散射测温技术实验研究了火焰结构、流场和温度场之间的相互影响关系。对比分析了贫燃稳定与富燃抬升状态下甲烷/空气预混火焰的燃烧场特性。实验结果表明：火焰结构、流场和温度场分布之间均存在直接联系。贫燃（当量比为0.8）火焰钝体上方为膨胀的高温低速回流区，利于火焰维持稳定；富燃（当量比为1.2）火焰倾向在受限空间出口与外界空气卷吸后着火，其钝体上方为类似冷态的低速低温回流区，无法点燃混合气，因而形成抬升火焰。分析各场局部分布信息获得火焰场间相互依赖规律：钝体火焰中，高温和低速对应已燃区，低温和高速对应未燃区。

Laser diagnostics of premixed bluff-body stabilized and lift-off flame in confined space

In a confined premixed bluff-body combustor, OH-PLIF (planar laser-induced fluorescence), PIV (particle image velocimetry) and Rayleigh scattering thermometry technologies were used to experimentally study the relationship among the flame structure, flow field and temperature field. Methane/air premixed flames under fuel lean stable and fuel rich lift-off states were compared and analyzed. Experimental results showed that there was a strong correlation among flame structure, flow field and temperature field. For fuel lean state (equivalence ratio of 0.8), the high temperature and low velocity inner-recirculation zone above the bluff-body helped maintain the stable flame; for fuel rich state (equivalence ratio of 1.2), the flame was prone to ignite after being entrained with the outside air, the low velocity and low temperature inner-recirculation zone similar to cold condition above the bluff-body cannot ignite the rich premixed gas, thus forming a lift-off flame. By analyzing the local distribution of the flame field, the field-to-field interdependency of premixed bluff-body flame was obtained: in bluff body flame, high temperature and low velocity zone corresponded to the burned zone, while low temperature and high velocity zone corresponded to unburned zone.