不同初始温度下甲烷-空气混合气层流燃烧速率的测定

摘要

利用高速纹影系统在定容燃烧弹中用球形火焰法测量了不同当量比和不同初始温度下的甲烷-空气混合气的层流燃烧速率.研究结果表明:拉伸火焰传播速率、无拉伸火焰传播速率和无拉伸层流燃烧速率均随初始温度的增加而增加.Markstein长度值随燃空当量比的增加而增加,随初始温度的增加而略微减小.浓混合气的甲烷一空气前锋面火焰稳定性比稀混合气高.不同初始温度下的无拉伸层流燃烧速率在化学计量比处达到最大值.基于试验数据拟合出无拉伸层流燃烧速率与当量比和初始温度的经验公式.%The laminar burning velocity of methane-air mixtures was measured under different initial temperatures and equivalence ratios by using the outwardly expanding flame and high-speed schlieren photog-raphy. The results show that the stretched flame propagation speed, the unstretched flame propagation speed and the laminar burning velocity are increased with the increase of initial temperature. The Mark-stein length is increased with the increase of equivalence ratio, but it decreases slightly with the increase of initial temperature. Flame front of the rich premixed mixture combustion shows higher stability than that of the lean mixture combustion. The laminar burning velocities reach their maximum values at the stoichio-metric equivalence ratio regardless of initial temperature. Based on the experimental data, an explicit ex-pression for the laminar burning velocity to initial temperature and equivalence ratio is correlated.