氮气稀释气对天然气燃烧特性的影响

为获得氮气稀释气对天然气燃烧特性的影响规律,在定容燃烧反应器中对不同当量比与初始压力下天然气的火焰传播特性、燃烧稳定性及燃烧特性进行了试验测试,并分析了氮气稀释度对天然气火焰传播特性、燃烧稳定性及燃烧特性的影响规律。研究结果表明:随着初始压力与氮气稀释度的升高,火焰前锋面将出现细小裂纹,火核逐渐向定容燃烧反应器上部漂移,火焰稳定性变差;随着初始压力的提高,马克斯坦长度明显变短,火焰稳定性变差,无拉伸火焰传播速度与层流燃烧速度明显降低,但最大燃烧压力显著升高。随着当量比的提高,层流燃烧速度与最大燃烧压力出现先增加后降低的趋势,两者的最大值出现在当量比为1.0时。马克斯坦长度随氮气稀释度的增加逐渐变短,表明火焰逐渐趋于不稳定;同时,无拉伸火焰传播速度、层流燃烧速度与最大燃烧压力随氮气稀释度的增加显著降低。

Effects of Nitrogen Diluent Gas on the Combustion Characteristics of Natural Gas

In order to gain the effects of nitrogen diluent gas on the combustion characteristics of natural gas, flame development characteristics, combustion stability and combustion characteristics of natural gas at different equivalence ratio and initial pressure were experimental studied in a constant volume combustion bomb, and the effects of dilution ratio of nitrogen on the flame development characteristics, combustion stability and combustion characteristics of natural gas were analyzed. The results show that micro-cracks appear on the flame front, flame core drift to the upside of the constant volume combustion bomb and flame instability is established with the initial pressure and nitrogen dilution ratio increasing. The instability of the flame front increasing, which is established by decreased Markstein length, and unstretched laminar flame propagation velocity and laminar burning velocity decrease and the maximum combustion pressure increase with the increase of initial pressure of the natural gas. At the same time, with the equivalence ratio increasing, the laminar burning velocity and the maximum combustion pressure illustrate an increase initially and then decreases gradually and the maximum values are measured at the equivalence ratio is 1.0. Furthermore, Markstein length is decreased flame instability is established with the increase of dilution ratio of nitrogen.Also, unstretched laminar flame propagation velocity, laminar burning velocity and the maximun conbustion pressure decrease distinctly with the increase of dilution ratio of nitrogen.