中文摘要：

在定容燃烧弹内研究了不同初始压力下天然气-氢气-空气混合气的火焰传播规律，得到了不同掺氢比例和初始压力下，不同燃空当量比时混合气的层流燃烧速率，并分析了火焰的稳定性及其影响因素．研究结果表明，随着天然气中掺氢比例的增加，混合气的燃烧速率增加，且增长速率逐渐加快，而马克斯坦长度值则随着掺氢比例的增加而减小，即火焰的稳定性下降．不同初始压力下，随着燃空当量比的增加，马克斯坦长度值在不同掺氢比例下均增加，显示火焰的稳定性增加．无拉伸层流燃烧速率随着初始压力的增加略有减小，且在化学当量比附近，变化的初始压力和掺氢比对无拉伸层流燃烧速率的影响最为明显．

英文摘要：

The laminar flame characteristics of natural gas-hydrogen-air mixtures were studied in a constant volume combustion bomb under various initial pressures. Laminar burning velocities under different initial pressures and at different equivalence ratios were obtained for natural gas-hydrogen-air mixture with different hydrogen fractions. Flame stability and its relevant factors were also analyzed. The results showed that as hydrogen fraction increases, laminar burning velocity increa- ses, while Markstein length decreases, i.e. flame stability decreases. Under different initial pressures,with the increase of equivalence ratio Markstein length tends to increase at different hydrogen fractions, which shows that flame stability increases. Unstretched flame burning velocity decreases slightly with the increase of initial pressure. The effect of initial pressure and hydrogen fraction on unstretched flame burning velocity was greatest near the stoichiometric equivalence ratio.