地面常重力（1g）条件下,丙烷/空气预混火焰向上传播的富燃极限为9.2%C_3H_8,而向下传播时的富燃极限仅为6.3%C_3H_8,二者之间存在明显差距。利用微重力条件下的实验,对燃料浓度从6.5%到8.6%（微重力实验中测定的可燃极限）范围内的丙烷/空气预混火焰特性进行了研究。实验发现,重力对近极限丙烷/空气火焰的传播有显著影响,影响程度随着当量比的增加而增大。微重力下丙烷/空气的富燃极限为8.6%C_3H_8（φ=2.24）,明显高于1g条件下向下传播火焰的可燃极限,略低于向上传播火焰的可燃极限。随着当量比的增大,根据压力变化曲线计算的火焰层流燃烧速度从8.5cm/s逐渐减小到2.7 cm/s,可燃极限处的层流燃烧速度与前人实验数据一致。
Flammability limits for flames propagating in rich propane/air mixtures under normal gravity conditions appeared to be 6.3%C_3H_8 for downward propagation and 9.2%C_3H_8 for upward propagation,and the concentration gap between the two limits was extremely large.In the present work,microgravity experiments were carried out to examine flame properties in propane/air mixtures over the specific range of concentration that extended from 6.5%C_3H_8 to 8.6%C_3H_8（the flammability limit found in the microgravity experiments）.It was found that buoyancy played a significant role in flames propagating near flammability,and the influence increased with equivalence ratio.The rich limit was determined to be 8.6%C_3H_8 under microgravity,which was far behind the limit for downward-propagating flame and close to the limit for upward-propagating flame at 1g.The laminar burning velocities,calculated on base of the pressure curves,gradually decreased from 8.5 cm/s to 2.7 cm/s with the increase of equivalence ratio,and burning velocity at the flammability limit was consistent with previous experimental data.
参考文献
| [1] | JOZEF JAROSINSKI;JERZY PODFILIPSKI;ANDRZEJ GORCZAKOWSKI;BERNARD VEYSSIERE .EXPERIMENTAL STUDY OF FLAME PROPAGATION IN PROPANE-AIR MIXTURE NEAR RICH FLAMMABILITY LIMITS IN MICROGRAVITY[J].Combustion science and technology,2002(9):21-48. |
| [2] | Laminar burning velocities and Markstein lengths of premixed methane/air flames near the lean flammability limit in microgravity[J].Combustion and Flame,2010(4):667. |
| [3] | K.J. Bosschaart;L.P.H. de Goey .The laminar burning velocity of flames propagating in mixtures of hydrocarbons and air measured with the heat flux method[J].Combustion and Flame,2004(3):261-269. |
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