For simulating the ignition transient in solid rocket motor (SRM) for high energy propellant, process of flame-spreading and the initial spreading speed of the gaseous phase or the solid phase are necessary. Two flame-spreading experiments for backforward facing step grain were carried out where a testing method based on thermocouple target-line and optical measurement methods were used. Results show that upward region of the propellant surface is ignited by the flame-spreading process,backward region is ignited by the gas of the upward propellant burning,and the step bottom region is ignited at last. The time of ignition transient by the resistance wire is so long that the speed for the upward gas to the backward region when burning is 57.78 cm · s -1 ,while the speed of flame-spreading on the upward region is only 4.92 cm · s-1.%模拟固体火箭发动机内的点火瞬态,必须了解其推进剂固相表面的火焰传播过程及给定初始气/凝相上的火焰传播速度.通过在推进剂表面嵌入热电偶丝的类靶线法及光电探测法,对后向台阶型装药的高能推进剂开展了两次火焰传播实验.结果表明,上游推进剂表面是由火焰连续传播所点燃,下游表面是由上游推进剂燃烧产生的燃气所点燃,台阶底部区域则是最后点燃.同时发现单纯由电阻丝点火建立的火焰传播过程时间较长,其中气相扩散并点燃下游推进剂表面的平均速率为57.78 cm·s<'-1>,上游火焰传播的平均速率仅为4.92 cm·s<'-1>.
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