粉末燃料冲压发动机内镁粉尘云层流燃烧模型

对粉末燃料冲压发动机预燃室内镁粉尘云燃烧过程进行了研究，建立了镁粉尘云的一维层流预混燃烧模型。研究表明，镁粉尘云层流火焰传播很稳定，燃烧过程中火焰结构基本不变，燃烧区很薄，而预热区厚度约是燃烧区的2-3倍。粉尘云中镁颗粒的蒸发和气相镁与氧气的均相反应是产生火焰的直接原因，也是火焰得以传播的关键。预热区气相温度升高主要靠燃烧区气体的导热和扩散过来的气相镁与氧气反应释放热量，而预热区颗粒相温度升高主要靠气相对其对流传热。分析了各参数对粉尘云燃烧的影响，颗粒相对浓度对粉尘云燃烧的影响比较复杂，在浓度较低的情况下，增大颗粒相对浓度有利于粉尘云快速燃烧；而在浓度较高的情况下，增大颗粒相对浓度则不利于粉尘云快速燃烧。随颗粒粒径的增加，火焰传播速度减小，火焰温度升高，预热区厚度增大。火焰传播速度和火焰温度随粉尘云初温增加线性增长，预热区厚度随粉尘云初温增加抛物线增长。数值模拟与文献中试验结果的变化趋势相一致。

Laminar combustion model of pulverized magnesium particle cloud in powdered fuel ramjet

The combustion process of pulverized magnesium particle cloud in powdered fuel ramjet preburner has been studied. A one-dimension premixed laminar combustion model of pulverized magnesium particle cloud was established. The studies show that the laminar flame propagation of pulverized magnesium particle cloud is very stable, and the flame structure is almost invariable in the combustion process; the combustion zone thickness is very thin and the preheat zone thickness is about 2-3 times as much as the former. It is the direct cause of flame and the key of flame propagation that the magnesium particles vaporization and the homogeneous reaction of magnesium vapor and oxygen in particle cloud; the preheat zone gas temperature rising depends mainly on the thermal conductivity of the combustion zone and the reaction heat of magnesium vapor which diffuse from combustion zone and oxygen while the preheat zone particle temperature rising depends on the convective heat transfer from gas phase to particle phase mostly. The effects of the interior parameters on the combustion of the magnesium particle cloud were analyzed. The effect of particle relative concentration on combustion of particle cloud is complex. When the particle relative concentration is low, increasing particle relative concentration is helpful for speeding up the particle cloud combustion process; when the particle relative concentration is high, increasing particle relative concentration is adverse to speeding up the particle cloud combustion process. With the increase of the particle size, the flame propagation speed is reduced, the flame temperature increases, the thickness of preheat zone increases. With the increase of the initial temperature of particle cloud, flame propagation speed and flame temperature are linear growth, preheat zone thickness is parabolic growth. The tendencies obtained by numerical simulation coincides well with that of the experimental results from the literature.