RP-3航空煤油五组分模拟替代燃料的层流燃烧特性

Laminar Combustion Characteristics of Five-Component Surrogate Fuel of RP-3 Kerosene

关键词:  RP-3航空煤油  替代燃料  层流燃烧速度  马克斯坦长度  火焰面不稳定性

Key words:  RP-3 kerosene  Surrogate fuel  Laminar combustion velocity  Markstein length  Flame instability

摘要:

为了研究一种RP-3航空煤油的五组分模拟替代燃料（包含摩尔分数为14%正癸烷、10%正十二烷、30%异十六烷、36%甲基环己烷和10%甲苯）的燃烧特性，在定容燃烧装置中对初始温度390K，400K和420K，初始压力0.1MPa和0.3MPa，当量比0.8~1.5的该五组分混合燃料进行了层流燃烧特性试验。通过对火焰照片进行边界提取和测量，获得了火焰面发展规律、马克斯坦长度和层流燃烧速率，并将试验结果与RP-3航空煤油的层流燃烧速度进行了对比，得出结论：温度升高会促进球形火焰面的传播；压力升高或混合气过浓和过稀都不利于五组分混合燃料的火焰传播。在本文的试验工况下，温度对火焰前锋面不稳定性的影响不明显；随着当量比增加，马克斯坦长度减小，质量扩散的作用逐渐增强而使火焰面变得不稳定；压力升高使火焰前锋面的不稳定程度明显加剧，表现为初始压力较高时火焰面破碎情况严重并出现大量细胞状结构。五组分混合燃料层流燃烧速度的峰值出现在当量比1.2左右，偏离该当量比时，火焰传播速度随着偏离量逐渐减小。通过与RP-3航空煤油的试验数据进行对比，发现在试验工况下，该五组分混合燃料与RP-3航空煤油的层流燃烧速度基本吻合。

Abstract:

In order to study the laminar combustion characteristics of a five-component surrogate fuel （comprising the mole fraction of 14% n-decane，10% n-dodecane，30% isohexadecane， 36% methylcyclohexane and 10% toluene）， laminar combustion experiments have been conducted in a constant volume chamber at initial temperature of 390K，400K and 420K， initial pressure of 0.1MPa and 0.3MPa， equivalence ratios of 0.8~1.5.The propagation law of the flame front， Markstein length and laminar flame speed are obtained by the boundary extraction and measurement of the flame photo. The experimental results were compared with laminar combustion velocity of RP-3 kerosene. The following conclusions can be drawn： An increase in temperature will accelerate the propagation of the spherical flame front. The increase in pressure and the over-rich or over-lean of the mixture is unhelpful to the flame propagation of the five-component mixed fuel. Under the operating condition， the effects of temperature on the flame front instability are not obvious. The Markstein length is reduced with the increase of the equivalence ratio， indicating that the enhancement of the mass diffusion results in an instability of the flame front. The instability degree of the flame front surface obviously increases with the initial pressure increases. The flame front is broken seriously when the initial pressure is higher and a large number of cell-like structures are present. When equivalence ratio is near 1.2，the laminar flame speed can be up to the maximum value， and the flame propagation speed gradually reduces as the equivalence ratio is deviated from 1.2. Compared with the experimental data of RP-3 kerosene， it is found that the laminar combustion velocity of the five-component surrogate fuel is basically consistent with that of the RP-3 kerosene under test conditions.