火焰加速和爆燃向爆震转变过程的数值模拟及试验验证

Numerical simulation and experimental study on flame acceleration and deflagration to detonation transition

为了研究火焰加速现象、爆燃向爆震转变和不稳定爆震向稳定爆震的转变过程,对带环形孔板的爆震室进行了数值模拟.研究发现用较低的点火能量对爆震室中的燃料和氧化剂点火产生层流火焰,在孔板的阻碍作用和火焰诱导激波以及反射波的加速作用下,经过几个孔板的阻碍加强作用,在火焰和强激波之间的未燃物中形成爆炸中心,最终引爆未燃混气.同时对爆炸波向稳定爆震转变过程中遇到孔板产生三波点,以及马赫波向入射波转变的全过程进行了分析;对不同燃料在不同当量比下的起爆距离进行了研究,并与试验结果进行了对比.通过分析,对火焰加速和爆燃向爆震转变的过程有了更加全面的认识,为进一步试验提供了参考.

Numerical simulations and experimental study in a detonation duct with orifice plates were carried out to study the phenomena of flame acceleration and the evolutions of deflagration to detonation transition（DDT） and unstable detonation to stable detonation.The results of numerical simulation show that laminar flame is generated by low energy ignition in detonation duct.The laminar flame becomes turbulent flame in the obstruction of orifice plate and under the acceleration action of shock waves and reflected waves.The turbulent flame is strengthened mutually with its induced shock waves.After a few orifice plates,＂hot spots＂ appear between the flame and the sharp shock wave,and then detonate the unburned mixture.Triple-point is formed in the evolution of weak detonation to stable detonation when detonation wave meets orifice plates.The evolution of Mach-pole to incident wave transition was also analyzed.The detonation initiation distances at different equivalence ratios were studied contrastively.Through calculation and analysis,deep understanding of flame acceleration and DDT were obtained,providing useful information for further experiment.