乙烯和汽油多循环脉冲爆震发动机起爆特性比较

为了研究脉冲爆震发动机(PDE)结构对其工作性能的影响,在内径为40mm、长为1050mm的气动阀式脉冲爆震发动机样机上,进行了气态乙烯/空气和液态汽油/空气的多循环起爆特性试验研究.研究结果表明:在25,30Hz和40Hz下都能在乙烯/空气中成功触发爆震波,40Hz下产生C-J(Chapman-Jouguet)爆震波,传播速度为1724m/s(低于C-J爆震波速度理论值1832.45m/s的5.6%),峰值压力为3.01MPa(高于C-J爆震波压力理论值2.79MPa的7.88%).在相同结构下,汽油/空气未能完成由缓燃向爆震转变的过程.通过对比两种燃料下的试验结果发现:相对于气态燃料,液态燃料受其蒸发过程的影响,在爆震管内的火焰加速缓慢,需要更多的强化燃烧装置来加速火焰,带来的总压损失也更大.因此,对于液态燃料改善雾化和蒸发,提高可爆混气的质量是其实现低阻起爆的关键.

Comparative ignition characteristics of ethylene and gasolene in multi-cycle pulse detonation engine

To investigate the influence of the structure of multi-cycle pulse detonation engine(PDE) on its operation performance,experiments of ethylene-air and gasoline-air mixtures initiation process in the aero-valve PDE of 1050mm length and 40mm inner diameter were performed.The results show that the detonation wave can be successfully initiated in the ethylene-air with frequency of 25,30Hz and 40Hz,and C-J(Chapman-Jouguet) detonation wave can be achieved at the frequency of 40Hz with detonation wave propagation velocity of 1724m/s(less 5.6% than the C-J detonation wave velocity theoretical value 1832.45m/s) and peak wave pressure of 3.01MPa(higher 7.88% than the C-J detonation wave pressure theoretical value 2.79MPa).While the deflagration to detonation transition failed to complete in gasolene-air.By comparison of the two results,it was found that the evaporation process dominated the initiation process in liquid fuels,thus slowering the flame acceleration process in the detonation tube.More novel and optimized-designed reinforced-combustion devices for accelerating the flame should be developed,which may cause higher total pressure loss.Thus,atomization and evaporation to improve the quality of the mixture is a key technology for detonation in the liquid fuel.