燃料喷孔数对非预混旋转爆震起爆过程的影响

Effects of the number of fuel injection orifices on rotating detonation initiation process under non-premixed conditions

环缝-喷孔结构是目前旋转爆震燃烧中经常采用的喷注结构之一。为了研究环缝-喷孔喷注结构中燃料喷孔数量对氢气/空气旋转爆震的影响,在保持燃料喷孔总面积不变的前提下,改变燃料喷孔数量(60、90、120、150),对冷态混合、爆震波起爆及稳定过程进行了数值模拟。总质量流量为206 g/s时,60和90喷孔喷注结构可以实现稳定爆震,而120和150喷孔则起爆失败;60喷孔构型中出现了多个旋转爆震波,并稳定于双波同向传播模态。总质量流量减小至103 g/s时,120和150喷孔可实现稳定爆震。结果表明,同一喷注结构在不同流量下的掺混效果并不相同,影响旋转爆震的起始;随着供给流量的提高,爆震波数量呈现增多趋势;氢气的轴向和径向分布越均匀,越容易形成旋转爆震波,周向分布越均匀,旋转爆震波传播速度越快,最高可达1827 m/s。

Slot-orifice injection scheme is now commonly used in rotating detonations.The influence of the number of fuel injection orifices(60,90,120,150)on rotating detonations inside an annular combustor were investigated numerically including the mixing process,the detonation initiation process and the detonation propagation process.For a total mass flow rate of 206 g/s,stable rotating detonation waves can be obtained when 60 and 90 orifices were used,while rotating detonation fails to be produced when 120 and 150 orifices were used.Multi-waves appeared in the 60 orifices configuration which finally transits into a stable dual-wave mode.When the total mass flow rate decreased to 103 g/s,stable detonation wave was able to be formed in the 120 and 150 orifices configurations.The results indicate that the mix ing process of the same injection configuration will be affected by the mass flow rate,which has a great impact on the detonation initiation.If distribution of H2 in axialand radial directions is more uniform,the detonation initiation becomes easier.It is also observed that the detonation wave number increases with the mass flow rate.Moreover,a more uniform distribution of H2 in the circumferential direction will lead to a faster detonation velocity,and a highest velocity of 1827 m/s has been obtained.