多循环喷雾爆震的特性研究

在无阀式脉冲爆震发动机模型机上进行了多循环喷雾两相爆震的实验研究．点火后爆震管内压力上升需要一定的延迟时间,但是迅速增压过程是在火焰传播到一定区域后开始的,在该区域形成向两个方向传播的压缩波,向未燃区传播的压缩波不断加强,形成爆震波,向已燃区传播的压缩波不断衰减;爆震峰值压力沿流向不断增加,压力上升速度加快,峰值随机差异放大;通过对压力历程的分析,用两种方法估算了两相爆震波诱导区的长度．实验中发现,两相爆震的点火延迟时间远大于爆燃向爆震转变的时间,两者之和相对于高频爆震循环非常可观,是限制两相脉冲爆震发动机频率提高的关键因素,并分析了多循环工作时的吸气和排气过程．

Investigations on Multi-Circle Spray Detonations

Experimental investigations are carried out on a 50 I. D. multi-cycle pulse detonation engine model, and liquid fuel(gasoline) is used. The average of pressure peak, as measured by piezoelectricity pressure transducer, increases versus distance to thrust wall before fully developed detonation comes into being. According to the pressure history, the pressure in detonation tube will rise abruptly, when the flame front advances a certain distance downstream the spark. Two compression waves spreading to opposite directions are formed. One is enforced by combustion and becomes detonation rapidly, and the other is weakened because of obstacles and insufficiency of fuel. Two methods are used to determine the induction length of two-phase detonation wave through the pressure history. Ignition delay time is found to be much longer than DDT ( deflagration to detonation transition) time, and the sum of the two changes little as cycle frequency increases. Together,they are the most important factors to control two-phase PDE operating frequency. Filling process and blowdown process are also analyzed.