氮气稀释气对天然气着火特性的影响

Effects of nitrogen diluent gas on the ignition characteristics of natural gas

为获得氮气稀释气对天然气着火特性的影响规律,对不同当量比、初始压力、初始温度以及氮气稀释系数下天然气的着火延迟时间进行了试验测试与数值计算,并分析了氮气稀释气对其着火特性的影响机理。结果表明,随初始温度的变化天然气着火延迟时间呈线性变化趋势;天然气的着火延迟时间随初始温度或初始压力的升高逐渐缩短,且受当量比的影响不明显;随着氮气稀释系数的增加,天然气的着火延迟时间逐渐延长,且促进天然气着火的关键反应步,R155:CH3+O2■O+CH3O与R38:H+O2■O+OH的敏感性系数将大幅度下降。

In order to gain the effects of nitrogen diluent gas on the ignition characteristics of natural gas,ignition delay times of natural gas at various equivalent ratios and initial pressures were experimental studied in a shock tube,and the effect of dilution ratio of nitrogen on the ignition delay time of natural gas was analyzed.Furthermore,the ignition characteristics of natural gas and the effect mechanism of nitrogen diluent gas on natural gas ignition were kinetically analyzed at different conditions with adopting Gri3.0 kinetic model.The results show that the variation trends of ignition delay time of natural gas with initial temperature is linearity at different conditions.With initial temperature or pressure increasing,the ignition delay time of natural gas is shortened.The effect of equivalent ratio on the ignition delay time is not obvious.With the increase of dilution ratio of nitrogen,the ignition delay time of natural gas is prolonged,and the sensitivity coefficients of the key reactions which promote gas ignition,R155:CH3+O2■O+CH3O and R38:H+O2■O+OH are greatly decreased.