中心点火火焰在药床中传播规律的试验研究

为了研究中心点火管火焰在药床中的传播规律，设计了可视化模拟试验平台，开展了不同点火药量、不同装药结构的中心点传火试验。采用高速图像采集系统记录了中心点火管火焰在药床中的传播过程，采用瞬态压力记录仪记录膛内压力的时空变化。结果表明，点火药量为20 g时，出火时间为0.6 ms；点火药量为30 g时，出火时间为1.5 ms；杆状装药床的传火时间平均为2.2 ms，粒状装药床的传火时间平均为3.4 ms，而杆粒混装药床的传火时间为3.1 ms。可见，点火药量对药床出火时间影响显著，较大的点火药量导致药床出火时间延长；不同装药床结构传火性能差异较大，单一杆状装药床传火性能优于单一粒状装药和杆粒混装药床，并且粒状装药床易形成气体壅塞，膛内会出现明显的压力波动现象；根据火焰传播时序位置点，利用一阶指数衰减函数拟合建立了火焰传播过程数学模型，拟合优度大于0.98。

Experimental research on the law of flame spreading in the charge bed of a central ignition tube

In order to investigate the development of flame spreading in the charge bed of a central ignition tube, a visualized ignition experiment platform was designed, and experiments were carried out with different ignition charge masses and charge structures. A high-speed image acquisition system was used to record the propagation process of ignition flame in the propellant bed at 10000 frames per second, and a transient pressure recorder was used to obtain the variation of pressure with time and position in the chamber. In addition, a synchronous trigger was used to connect the high-speed image acquisition system, the transient pressure recorder and the ignition system of the experimental platform, giving the system a trigger zero point, which is convenient for the statistical analysis of subsequent experimental phenomena. The experimental results show that the time of flame-appearing from the ignition tube into the combustion chamber is 0.6 ms when the mass of the black powder is 20 g. However, the time increases to 1.5 ms when the mass of the black powder is 30 g. The average flame-spreading time of the stick charge structure is 2.2 ms, the average flame-spreading time of the granular charge structure is 3.4 ms, and the average flame-spreading time of the mixed charge structure is 3.1 ms. The results indicate that the mass of the black powder in an ignition tube has a significant effect on the time of flame-appearing from the ignition tube, and the higher black powder mass lead to the longer flame-appearing time. The performances of flame-spreading in different charge bed structures are quite different. The performance of flame-spreading in the stick charge structures is better than that in the granular charge structures and mixed charge structures. In addition, the pressure fluctuations will appear in the chamber due to gas choking in the granular charge structures. A mathematical model of the flame-spreading process was established by fitting the first-order exponential decay function according to the time sequence of the position of flame, and the goodness of fit is greater than 0.98.