多循环两相爆震理论、实验与数值模拟

【作者】 李牧；

【导师】 严传俊；

【作者基本信息】 西北工业大学 ， 航空宇航推进理论与工程， 2005， 硕士

【摘要】 脉冲爆震发动机(PDE)是一种利用间歇式或脉沖式爆震波产生的高温、高压燃气来产生推力的新概念发动机,这种发动机具有很高的热循环效率、结构简单、适用范围宽广等优点,很多国家都已经将其列入重点发展的先进推进系统研究计划之中,开展了大量研究。其中自吸气两相脉沖爆震发动机更为接近工程实用,是目前研究的重点。 本文回顾了爆震燃烧和脉沖爆震发动机的研究历史和现状,根据作者对爆震波和脉沖爆震发动机的理解,分析了爆震点火、DDT(deflagration-to-detonation fransiticn)过程、非理想爆震和喷雾两相爆震,对自适应无阀脉沖爆震发动机循环过程和其中的问题提出了自己的看法。通过实验,对多循环两相喷雾爆震特性进行了研究,并根据实验结果分析了制约两相爆震波发动机工作频率的因素,指出着火延迟时间是一个决定性的参数,并提出将爆震循环分为热态和冷态两部分;根据对多循环两相喷雾爆震的实验结果分析,进一步探索了提高PDE循环频率的方法,通过对发动机雾化方式,进气方式和其他结构的优化,实现了67Hz的两相爆震循环;设计加工并调试了500-800N脉冲爆震发动原理机样机,同时研究了收敛、扩张、组合喷管对PDE推力、比帅的影响,其中收敛引射组合喷管性能最佳。在数值模拟方面,采用二维轴对称模型分析了点火能量、障碍物形式对爆震起爆和传播的影响,成功的模拟了爆燃到爆震的转变;采用同样的方法,模拟了多循环爆震引射过程,与试验结果基本吻合,分析了爆震引射的激波压缩加速、射流卷吸、惯性和压差三种作用机制。更多还原

【Abstract】 Pulse detonation engine (PDE) is a new concept of propulsive device, which use high temperature and pressure gas produced by intermittent or pulsed detonation wave to generate thrust. PDE has many desirable advantages, including high thermodynamics cycles efficiency, simple configurations, and large range of usage, etc. so various research plans about PDE have been laid and carried out. Air breathing two phase PDE which more approaches engineering application now is the current foucs of worldwide PDE research.Firstly history and current status of detonation and pulse detonation engine have been reviewed, analysis according to author’s understand, on detonation initiation, DDT(deflagration-to-detonation transition) process, nonideal detonation, spray detonation is established roughly. Also different mechanisms of self-adapting valveless gas-phase and two-phase PDE were detected through different purge gas. Large amount of experiment investigations have been carried out: characteristics of multi cycle spray detonation was studied through multi channel parallel pressure measurement, that result in discovery of many factors which defines PDE’s maximal cycle frequency. Among the factors ignition delay time may has the most powerful effect on frequency. A new concept described in the paper: pulsed detonation cycle can be divided into hot time and cool time. Based on the analysis above, a series of explorers were tried including modification of injector, ignition zone, air supply mode and other structures, And now the maximal frequency of spray detonation cycle can reach 67Hz. A proof PDE of 500-800N thrust was defined and tested. Another investigation is on different nozzles such as convergent, divergent, combination of convergent and ejector, and it’s concluded that combination nozzle has the highest performance. In another side, numerical simulation is a cheapest method to look inside the detonation wave, a 2D axisymmetrical model was used to simulate and analyse detonation initiation, propagation and interaction with obstacles, DDT processhas been simulated successfully. In multi cycle simulation, 3 different ejecting mechanism of PDE with a simple cylindrical ejector was found which is called: (1) air compression and acceleration by Shockwave; (2) shearing and dragging; (3) inertia and pressure grads.更多还原