脉冲爆震发动机喷管流动的数值模拟

A numerical simulation on the nozzle flow of pulse detonation engine

为了研究喷管形状及充气状况对脉冲爆震发动机推进性能的影响,发展了基于有限速率基元化学反应模型的网格自适应有限体积程序,对影响脉冲爆震发动机推进性能主要过程进行了数值模拟,计算结果和相应的实验结果较为一致。锥形喷管的算例表明,不仅锥角对喷管性能有重要影响,而且同一锥角下喷管内的充气状况对喷管性能也有重要影响。在喷管内充空气情形下,爆轰波进入喷管后迅速衰减为激波,扩张管道的超声速膨胀使得喷管壁面压力显著下降,从而削弱了喷管提高脉冲爆震发动机推进性能的作用。在喷管内充燃气情形下,爆轰波进入喷管后可一直维持到喷管出口,显著提高了脉冲爆震发动机的推动性能。

A numerical simulation of detonation wave propagating through a divergent channel was carried out to investigate the nozzle effect on the performance of pulse detonation engine. Finite rate chemical reaction model was used during the calculation, and grid adaptive finite volume method was programmed for obtaining good resolution of the flow field. It was found that the nozzle shape and the filling condition play very important roles on the impulse of pulse detonation engine. Detonation wave decays into a shock wave as soon as it enters the nozzle for the case of incombustible gas is filled in the nozzle, and it is possible that the pressure on the nozzle wall is decreased to be lower than the ambient pressure due to the supersonic expansion, which is worse than with no nozzle. On the other hand, the thrust will be greatly enhanced for the case of combustible gas fully filled in the nozzle, since the nozzle wall is supported by the high pressure behind the detonation.