论文部分内容阅读
在自行研制的杯式燃烧器的基础上,采用实验与数值模拟相结合的方法对水蒸气抑制熄灭甲烷/空气扩散火焰的过程进行了研究,分析火焰抑制熄灭现象产生的过程与作用机理,得到了临界灭火浓度与协流氧化剂流量的变化规律.结果表明,水蒸气抑制熄灭杯式燃烧器扩散火焰是典型的局部火焰熄灭机理.随着水蒸气浓度的增加,杯式燃烧器扩散火焰的根部首先向内收缩并悬举至新的稳定高度,当根部反应核的燃烧速率随着火焰温度下降受到极大抑制后,火焰根部的预混区将因更多水蒸气的扩散稀释作用而无法继续维持火焰向外的振荡传播过程,火焰会脱离燃烧杯面而熄灭.破坏火焰根部核心燃烧区的反应条件是熄灭扩散火焰的关键.水蒸气临界灭火浓度在一定的氧化剂流量范围内不依赖于空气流量,在临界灭火浓度曲线上存在一“平缓区”.实验测得的临界灭火质量百分比浓度分别为水蒸气(16.7±0.6)%、二氧化碳(15.9±0.6)%、氮气(31.9±0.6)%,与数值模拟结果合理吻合.
On the basis of self-developed cup-type burners, the process of quenching methane / air diffusion flame by water vapor was studied by the combination of experiment and numerical simulation, and the process and mechanism of flame suppression quenching were analyzed. The results show that the water vapor suppression of the cup-shaped burner diffusion flame is a typical local flame extinguishing mechanism.With the increase of water vapor concentration, the root of the cup-burner diffusion flame When the combustion rate of root reaction nuclei is greatly reduced with the decrease of flame temperature, the premixed zone of flame root will not be able to continue due to the diffusion and dilution of more water vapor Maintain the flame outward oscillation propagation process, the flame will be off the burning cup surface and extinguished.Raw flame root reaction zone core combustion zone is the key to extinguishing the diffusion flame.The critical concentration of water vapor in a certain range of oxidant flow does not depend on the air Flow, there is a “flat zone” in the critical fire extinguishing concentration curve.Experimental measured critical fire extinguishing quality The specific concentrations were 16.7 ± 0.6%, 15.9 ± 0.6% and 31.9 ± 0.6%, respectively, which were in reasonable agreement with the numerical results.