麻疯树油/RP-3航油混合燃料燃烧特性实验研究

Experimental Study on Combustion Characteristics of Jatropha Oil/ RP-3 Kerosene Blended Fuel

关键词:  替代燃料  麻疯树油  混合燃料  定容燃烧弹  马克斯坦长度  无拉伸火焰传播速度

Key words:  Alternative fuel  Jatropha oil  Blended fuel  Constant volume incendiary chamber  Markstein length  Unstretched flame propagation speed

摘要:

为研究麻疯树油/RP-3航空煤油混合燃料的燃烧特性，在定容燃烧弹内完成了体积混合比分别为1:0，1:1和1:3，初始温度500K，初始压力0.1MPa，当量比为0.7~1.5混合燃料的实验。分析得到了混合燃料的火焰发展特性、火焰半径变化率、拉伸火焰传播速度、马克斯坦长度、无拉伸火焰传播速度等燃料燃烧特性，并与RP-3航空煤油对比。得到以下结论：在当量比为0.7~1.2时，火焰传播稳定，火焰前锋面较光滑；在当量比增至1.3~1.5时，火焰前锋面出现大量裂纹、胞状结构和微型火团，与其他大分子碳氢燃料的燃烧性质相似；在初始温度和初始压力一定时，无拉伸层流火焰传播速度随当量比先增加后减小，在当量比为0.9~1.0附近时，无拉伸层流火焰传播速度达到最大值；混合燃料的马克斯坦长度与当量比呈反比，在当量比为0.7~1.2时，马克斯坦长度为正值，燃烧趋于稳定；在当量比为1.3~1.5时，马克斯坦长度为负值，燃烧趋于不稳定。与RP-3航空煤油对比，掺有麻疯树油时马克斯坦长度轻微降低，燃烧稳定性稍差；在当量比小于1.0时，无拉伸火焰传播速度轻微降低，在当量比大于1.0时，无拉伸火焰传播速度显著降低。

Abstract:

In order to study the combustion characteristics of Jatropha oil / RP-3 kerosene blended fuel, experiments were carried out in constant volume incendiary bomb with volume mixing ratio 1:0，1:1 and 1:3, initial temperature of 500K, initial pressure of 0.1MPa, and equivalence ratios of 0.7~1.5, respectively. The combustion characteristics such as flame propagation characteristic, flame radius change rate, tensile flame propagation speed, Markstein length, and unstretched laminar flame propagation speed were obtained. And compared with RP-3 kerosene， the following conclusion is drawn: At the equivalence ratios of 0.7~1.2, the flame propagation is stable and the flame front is relatively smooth; when the equivalence ratio increases to 1.3~1.5, a large number of cracks, cell structures, and micro-fire clusters appear on the flame front. This is similar to the combustion behavior exhibited by other macromolecular hydrocarbon fuels. When the initial temperature and initial pressure are constant, the flame propagation speed of the unstretched laminar flame of the blended kerosene fuel increases with the equivalence ratio and then decreases. When the equivalence ratio is around 0.9~1.0, the unstretched laminar flame propagation speed reaches a maximum value. The Markstein length of blended fuel decreases with increasing equivalence ratio. When the equivalence ratio is 0.7~1.2, the Markstein length is positive and the combustion tends to be stable. At the equivalence ratio of 1.3~1.5, the Markstein length is negative and the combustion tends to be unstable. Compared with RP-3 kerosene, when jatropha oil was mixed in, the Markstein length of blended fuel decreased slightly and the combustion stability was slightly worse. When the equivalence ratio is less than 1.0, the unstretched laminar flame propagation speed decreases slightly, and when the equivalence ratio is more than 1.0, the unstretched laminar flame propagation speed decreases significantly.