【作者】 黄玥；

【导师】 唐豪；

【作者基本信息】 南京航空航天大学 ， 环境工程， 2008， 硕士

【摘要】 尾喷管是脉冲爆震发动机(PDE)的重要部件,其作用就是将爆震室排出的高温高压燃气所包含的热能通过在尾喷管中继续膨胀转变为动能,以便获得尽可能大的推力,对提高发动机的推进性能起着重要的作用。脉冲爆震发动机尾喷管流动是周期性的、非定常的,存在复杂的激波、膨胀波、接触面的相互作用。这给脉冲爆震发动机喷管的设计和分析带来了很大的挑战。本文对脉冲爆震发动机的尾喷管流场以及喷管性能进行了研究。主要做了以下工作:(1)结合了吸气式脉冲爆震发动机的工作原理以及循环,建立带喷管的脉冲爆震发动机简化的性能计算模型。利用计算模型估算了单次脉冲循环的脉冲爆震发动机的性能。(2)通过了数值模拟的方法对接不同结构喷管的脉冲爆震发动机进行了单脉冲研究,观察了爆震燃烧室和喷管流场的变化情况,并对不同喷管的性能进行了分析。数值模拟主要采用的是带有限速率化学反应的二维迎风型TVD格式的CFD程序,燃料采用了完全当量比的H2/空气混合物。研究的喷管结构包括直延伸喷管、收敛喷管、扩张喷管、收敛扩张喷管和引射器的喷管。数值模拟结果表明,喷管对PDE的流场产生了显著的影响;喷管对PDE的推进性能的提高有一定作用,每种喷管的性能并不相同。为了提高PDE的推进性能,PDE喷管应该可以减小排气激波的强度,同时保持爆震管出口处的高背压。(3)利用了CFD程序研究了无阀吸气式多管PDE的共用喷管的流动特性和推进性能。结果表明:共用喷管对PDE流场会产生重要影响,设计合理的共用喷管对优化多管PDE的性能和保证协调稳定的工作具有重要作用。更多还原

【Abstract】 Exhaust nozzle is a key component of pulse detonation engine (PDE). It plays a critical role in converting the thermal energy of combustion gases in the detonation chamber to directed kinetic energy in the exhaust, so as to obtain maximum thrust performance.The nozzle designs and analysis for PDE poses a significantly greater challenge due to the transient nature of the flow field. This dissertation deals with the modeling and simulation of the PDE with different nozzles, the entire internal and external flow evolutions of different nozzles during a full cycle are investigated and propulsive performance is calculated. Some researchs have been done as follow:Based on the working principle and operating cycle process of PDE, two different analytical models for the performance of a single-cycle pulse detonation engine are established. The Performance of PDE was theoretically analyzed by using these models.Numerical simulations based on upwind total-variation-diminishing (TVD) scheme are carried out for single-pulse PDE with different nozzles. Five PDE nozzle geometries: straight extension, convergent nozzle, divergent nozzle, convergent -divergent nozzle, and ejector are evaluated. The flow evolutions of different nozzles during a full cycle are investigated, much effort was expended to analysis the effect of nozzle configuration on the system performance. The results indicate that the nozzles affect the chamber flow dynamics significantly and change performance through modification of the gas expansion process. Further analysis revealed that nozzle performance depends not only on its effect on the shock wave strength, but also on its effect on the downstream unsteady exhaust flows.The flow field interaction among detonation tubes sharing a common nozzle in a multi-tube PDE is explored. The evaluations are based on a two-dimensional analysis of single-pulse operation. Three common nozzle configurations are considered. The present study indicates that the common nozzles have a significant effect on flow field of detonation tube. In order to greatly enhance system performance, a PDE nozzle should be able to reduce exhaust shock strength and at the same time maintain high back pressure at the detonation tube exit.更多还原