马赫数为4的超燃发动机碳氢燃料点火试验

在直连式脉冲燃烧风洞设备上,开展了模拟马赫数为4,总温为935K的超燃发动机碳氢燃料点火试验.试验利用了点火器加引导氢气、引导氢气自燃辅助点火、节流加引导氢气3种辅助点火方式成功实现了乙烯燃料的点火并维持了稳定燃烧.试验研究发现:利用氢气自燃辅助乙烯点火,氢气质量流量范围为0.43～12.61g/s,氢气质量流量过大不能成功点火；利用节流加引导氢气的辅助点火方式,节流量为10％～30％,氢气注油压力为5 MPa能够可靠点火.最后研究了乙烯从凹槽上游和从凹槽底部注油的发动机贫油点火极限和富油工作极限,研究发现两者的贫油熄火极限相近,为当量比为0.077,而富油工作极限差别较大,当量比分别为0.327和0.471.

Experiments on hydrocarbon fuel ignition for scramjet at Mach 4

Hydrocarbon fuel ignition experiments were performed on directly connected pulse combustion facility.The test inflow parameters included stagnation temperature of 935K and the Mach number of 4 at the entrance of isolator. Gaseous ethylene was ignited successfully and combustion was maintained stable by employing three combination assistant ignition methods: torch igniter combined with pilot hydrogen, self-combustion of pilot hydrogen and air throttle combined with pilot hydrogen. The experimental results indicate that when employing self-combustion of pilot hydrogen, the mass flow rate of hydrogen should be ranged from 0.43~12.61g/s, and higher mass flow rate of hydrogen isn't helpful to ignition; for air throttle combined with pilot hydrogen ignition method, the injection pressure of hydrogen should be set at 5MPa, and the throttle mass flow rate should be 10%~30% of inflow mass flow rate. At last the lean blow-out limit and rich operation limit of scramjet were researched with ethylene injected from upstream of cavity or cavity floor.The results show that two injection schemes have similar lean blow-out limits at equivalence ratio of 0.077, and the rich operation limits varies a lot at equivalence ratios of 0.327 and 0.471 respectively.