渐缩微喷管内氢气掺混甲烷预混燃烧实验研究

在出口直径为1.6 mm的石英渐缩喷管中进行预混燃烧实验,研究不同当量比(实际供给的空气量与理论上可完全燃烧需要空气量之比)以及混合比R（甲烷体积与燃料总体积比）下氢气/甲烷/空气在微尺度喷管内稳燃范围、输出推力、壁面温度分布等特性.通过实验发现,混合比越大,对应的稳定流速下限越小,当量比越大,对应的稳定流速下限越大,其中Φ=0.7,稳燃流速范围最大.当Φ=0.6时,壁面最高温度随着R的增大而减小,但是当Φ=0.9时,壁面最高温度几乎没有变化.壁面最高温度出现在Φ=0.7时,为761 ℃.火焰分为2层,内层颜色基本为淡蓝色,表明燃烧中氢气被点燃.当输入功率（由氢气和甲烷的热值与各工况体积流量计算获得）Q=13 W时,Φ=1.0时得到的比冲最大,效率最高.

Experiments on hydrogen combustion with addition of methane in micro converged nozzle

Experiments of hydrogen premixed combustion with the addition of methane were conducted in a micro converged nozzle with outlet diameter of 1.6 mm. The effects of different equivalence ratios (the ratio of actual amount of air supply and theoretically complete combustion air volume) and mixing ratios R(VCH4/Vfuel) on hydrogen/ methane /air premixed combustion were performed. The experiments focused on the stable ranges, thrust output and the temperature distribution of wall surface. Experimental results show that the lower limit of stable inlet velocity decreases when R increases, and it increases with the increase of equivalence ratio. The largest width appears atΦ=0.7. When Φ=0.6, the highest wall temperature drops with the increase of R; however, whenΦ=0.9, the highest wall temperature is nearly unchanged; the highest wall temperature is measured whenΦ=0.7 ,which is 761 ℃. Two layers of the flame in homogeneous combustion is observed. The inner layer flame color is almost light blue, which shows that the hydrogen burns first and then the methane. When input power Q≈13 W, the maximum thrust output and the highest efficiency appears atΦ=1.0.