摘要：
An engine flow path of a base geometry consists of the elaborately designed isolator and a detonation combustor with a length to diameter ratio of 20, along with a comparison group of four different geometries, were studied numerically by means of single detonation to investigate the propagation characteristics of back-pressure in an air-breathing pulse detonation engine.Parameters of the back-pressure, including propagation speed, pressure peak, and its decay rate as well as the total pressure recovery coefficient of the base model were considered and discussed.The results demonstrate that the designed isolator is able to reduce the backpropagation speed and the back-pressure peak effectively.The detonation combustor with a larger length to diameter ratio contains more fuel and oxidant, which needs more efforts to prevent the back-pressure.The decay rate of the pressure peak is mainly affected by the geometry of the isolator at the early stage of the back-propagation process, and afterwards it depends on the distance of the back-propagation.When the inlet pressure is given, the detonation combustor with a smaller length to diameter ratio has a more rapid exhaust process, and therefore, a slighter back-pressure propagation phenomenon.Large total pressure losses are not found in the designed isolator when the Mach number of the incoming flow is between 0.15～0.80 under sea level conditions.%为研究吸气式脉冲爆震发动机反压的传播规律,以一种特殊构型的隔离段与长径比为20的爆震室构成的发动机流道作为基准模型,并选取4种构型作为对照组,进行了单次爆震的数值模拟.研究了反压的反传速度、峰值及其衰减率,计算了基准模型的总压恢复系数.结果表明:设计的隔离段能有效降低反压的反传速度和峰值;爆震室的长径比越大,所含的燃料和氧化剂越多,反压越难以抑制;在反压向上游传播的初期,压力峰值的衰减率主要受隔离段结构的影响,之后则主要取决于反传距离;当来流压力一定时,长径比越小的爆震室,排气过程越迅速,反压下降得越快;在海平面大气条件下,当来流马赫数为0.15～0.80时,所设计的隔离段并未造成大的总压损失.
