【作者】 梁宗宪；

【导师】 杨基明；

【作者基本信息】 中国科学技术大学 ， 流体力学， 2006， 硕士

【摘要】 本文采用基于有限速率基元化学反应模型的网格自适应有限体积方法，数值模拟以脉冲爆轰发动机为背景的爆轰波通过扩张喷管的流场，研究了喷管形状及喷管充气状况对脉冲爆轰发动机推进性能的影响。结果表明，以氢为燃料的等截面爆轰管冲量在某一比例合适的部分填充时达到最大，而对较大扩张角的喷管来说，其冲量一般随喷管内可燃气体填充比例的增加而增加，比冲通常随可燃气体填充比例的减少而增加；合适的喷管和燃料填充率能使比冲显著提高。具体体现在： (1) 对氢-氧混合物的爆轰波在直管传播来说，爆轰波遇到可燃气体-空气界面时反射激波，使得端部推力面压力上升，结果造成冲量在可燃气体填充比例合适时达到峰值，这与以乙烯为燃料的爆轰发动机冲量一直随燃料填充率增大而增大的情况不同：此外，比冲随可燃气体填充比例的减少而增加。 (2) 对非0度扩张角的喷管，本文以15°和45°为代表，分别模拟了喷管中氢-氧燃气填充状况为不充、充一半和完全填充的条件下流动之间的差异。发现对于扩张角较小的15°喷管来说，端壁推力面所提供的冲量明显占主导地位，故而其效能亦与直管类似；45°喷管发动机的冲量则主要由喷管推力部分引起，喷管中可燃气体填充条件的改变所引起端壁推力冲量部分的变化很小。 (3) 45°喷管在所有同样填充率条件下都获得了比15°喷管更大的冲量和比冲，这也说明尾喷管压力作用面积对爆轰发动机效能起到了积极的作用。更多还原

【Abstract】 A grid adaptive finite volume method combined with kinetic chemical reaction model was developed to simulate the flow field of detonation wave propagating through a divergent channel. The investigation was focused on the performance of pulse detonation engine depending on the nozzle shape and the partial-fuel fill in the chamber. It was found that the impulse of the straight detonation tube with a hydrogen-air mixture achieves its maximum at a certain filling rate. On the other hand, as to the nozzles with a larger divergent angle, the impulse increases with increase fuel filling rate, although in most case the specific impulse increases with decreasing fuel-filling rate. The specific impulse can be obviously improved with properly designed nozzle shape and fuel filling rate. The main conclusions are summarized as follows:(1) When the detonation wave in hydrogen-air mixture encounters the interface of combustible mixture-air in straight tube, a reflected shock will be generated, which causes pressure increase on the thrust wall. As a result, the impulse of the straight detonation tube achieves its maximum at a certain filling rate, which differs from the case of ethylene-oxygen mixture as fuel, whose impulse increases with the increase in fuel filling rate. On the other hand, the specific impulse increases with the decrease in fuel filling rate.(2) 15° and 45° nozzles were chosen as representations of no-straight channels to simulate the flow fields under three nozzle-filling conditions, namely full-filled, half-filled and none-filled. It was found that the impulse provided by the end wall of tubes are dominant for 15° nozzle, so it’s performance is similar to the case of 0° nozzles. However, the impulse of 45° nozzle is mainly provided by the nozzle. The variations of the filling conditions in the nozzle cause little change in the fraction of the impulse provided with thrust wall.(3) 45° nozzles overwhelm 15° ones in the impulse and the specific impulse under all filling conditions, which means the area on which pressure can act is one of the key factors of pulse detonation engine efficiency.更多还原