Methane hydrogen hybrid turbulent combustion phenomena in a high temperature low oxidizer

实验和数值研究了氧化剂预热和燃料和氧气稀释水平对相反湍流场燃烧现象的影响。氧化剂预热和稀释水平的特征是化学计量混合物分数（Fst）的大小。作为消光极限的总体特征，即使一侧燃料浓度降低，另一侧的燃料浓度也可以保持火焰的增加。显然，湍流条件对消光极限有显著影响。消光极限不受LPF侧湍流的影响。然而，在LDF侧加入湍流的情况下，消光极限增大。在F_<st><0.5范围内，层流火焰和紊流火焰的消光界限与层流火焰明显分离。在消光条件下，可以观察到局部淬火现象。若大面积局部淬火发生在滞止点，则局部淬火区发展到全局绝灭。然而，局部灭绝并不总是导致全球灭绝的原因。在大多数情况下，火焰可以从局部淬火现象中恢复。有两种不同的局部淬火恢复机制。一种是局部淬火，发生在停滞点。在这种情况下，LPF传播到局部淬火区域。然后火焰可以从局部淬火现象中恢复。另一种局部淬火发生在凝固点的外部。在这种情况下，局部淬火区随着从凝固点发散出来的气流漂移。火焰可以根据相反的流动特性自动恢复。

The effect of oxidizer preheating and dilution levels of fuel and oxygen on the combustion phenomena were investigated experimentally and numerically on an opposite turbulent flow fields. The oxidizer preheating and dilution levels are characterized by the magnitude of stoichometric mixture fraction (Fst). As overall feature of the extinction limits, the flame can be maintained to increase in the fuel concentration of opposite side, even when one side fuel concentration is reduced. Obviously, the turbulence conditions affect significantly on the extinction limits. The extinction limit is not influenced on the turbulence added in the LPF side. However, in the case of the turbulence added in the LDF side, the extinction limits is increased. In the regime of F_<st><0.5, the extinction limits of the laminar flame and turbulent flame are significantly dividing from the laminar flames.Near the extinction condition, the local quenching phenomena can be observed. If the large area of the local quenching occurs in the stagnating point, the local quenching area developed to the global extinction. However, the local quenching is not always trigger to develop the global extinction. Most of cases, the flame can recover from the local quenching phenomena. There are two distinct the local quenching recovery mechanism. One is the local quenching, which occurs at the stagnation point. In this case, the LPF propagates into the local quenching area. Then the flame can be recovered from the local quenching phenomena. The other local quenching occurs at the outside form the stagnating point. In this case, the local quenching area is drifted with the diverging flow from the stagnating point. The flame can be automatically recovered in accordance with the opposite flow properties.