Plasma Jet Flame-Stabilization Mechanism in Supersonic Combustion

对高速气流中氢气扩散火焰上游喷射等离子体射流的点火和阻燃机理进行了研究。等离子体射流是在较低功率范围内用含有O_2、N_2和H_2等活性物种的Ar气体操作的。结果表明，对于点火和阻燃，原料中活性物质的浓度比等离子体喷射功率更重要。这一事实表明了等离子体射流产生的活性物质的有效性，而不是等离子体射流热能的有效性，以及与产生的自由基总量相比，提供给燃料射流着火点的自由基浓度的重要性。研究还发现，添加剂的有效性顺序为O_2*N_2和GT；H_2，添加自由基促进燃烧反应的数值模拟结果与实验结果定性一致。对于超音速气流，在等离子体射流喷射之前观察到斜激波，为了建立点火和阻燃，必须增加等离子体射流的功率，但在亚音速气流的情况下，不同原料的等离子体射流的效果顺序是相同的。

Studies on the mechanism of ignition and flame-holding by upstream injection plasma jets were conducted for H_2 diffusion flames in high speed air streams. The plasma jets were operated with Ar gas involving active species such as O_2, N_2 and H_2, in the range of relatively low power. It was observed that for ignition and flame-holding, the concentration of active species in feedstock is more important than plasma jet power. This fact suggests the effectiveness of active species produced by plasma jets, rather than that of plasma-jet thermal energy, and also the importance of radical concentration supplied to the ignition-point of a fuel jet, compared to the total quantity of radicals produced. It was also found that the effectiveness of additives is in the order, O_2 * N_2 > H_2, and the results of numerical simulation on combustion-reaction promotion by the radicals added agreed qualitatively with the experimental ones. In the case of supersonic air streams, where an oblique shock wave is observed ahead of plasma jet injection, for the establishment of ignition and flame-holding the power of plasma jet must be increased, but the order of effectiveness of plasma jets, differ in the feedstock, are same in the case of subsonic air strems.