固体燃料冲压发动机自持燃烧的影响因素

采用试验和仿真方法,研究了固体燃料冲压发动机(SFRJ)自持燃烧的主要影响因素。研究结果表明:SFRJ内为典型的扩散火焰,化学反应特征时间与反应物停留特征时间的比值是影响发动机自持燃烧的关键参数,该值越小,扩散火焰越稳定;本文研究工况下,较小的后台阶高度即可保证发动机实现自持燃烧,后台阶稳定火焰的物理原因是在固体燃料表面附近形成一个低速区,保证了固体燃料的分解燃烧,当台阶高度为0时,由于化学反应特征时间与反应物停留特征时间的比值迅速增加,SFRJ无法自持燃烧;台阶高度较小时,点火过程会对SFRJ的稳定燃烧产生影响,SFRJ可能会出现熄火复燃现象。

Influencing factors for self-sustained combustion of solid fuel ramjet

By simulation and test,the parameters which influence the self-sustained combustion of the solid fuel ramjet (SFRJ) are investigated.The results show that the combustion in SFRJ is diffusion-controlled,and the ratio of characteristic chemical reaction time to characteristic residence time is the critical parameter influencing the self-sustained combustion of ramjet.The smaller the ratio is,the more stable the flame will be.Under the conditions of the present research,a small step height can guarantee the self-sustained combustion of ramjet.The physical reason for the stabilization of combustion behind a backward-facing step is that existence of a low speed flow area near the solid fuel surface guarantees the pyrolysis and combustion of the solid fuel.When the step height is 0,the flame will go out as the ratio of characteristic chemical reaction time to characteristic residence time increases quickly.When the step height is small,the ignition process may have influence on stable combustion of the SFRJ,and reburning may occur after flameout.