燃烧波旋转传播过程中爆燃向爆震转变机制研究

Spiral detonation chamber of pulse detonation engine and annular detonation chamber of continuous rotating detonation engine are detonation devices with great potential for engineering applications. To achieve detonation, indirect initiation with deflagration to detonation transition (DDT) is the engineering direction of future development. In the spiral/annular detonation chambers, propagation paths of combustion wave are rotating. Therefore, a common scientific problem is involved. That is the deflagration to detonation transition mechanism of combustion wave with rotating propagation. And the current research on this aspect is still in the exploratory stage. In this project, the characteristics of flame propagation in the bending sections with/without side opening will be researched first. This is for the first phase of the DDT phenomena where conditions for the onset of detonation are created by the processes of flame acceleration, vorticity production, formation of jets, and mixing of products and reactants. Then the interactions between shock wave and flame in the bending sections with/without side opening will be studied. This is for the second phase of DDT phenomena where the onset of detonation occurs. Finally, spiral tube with/without side opening will be used to investigate the continuous evolution of combustion mode during different ignition processes. The goals of the project are to acquire the deflagration to detonation transition mechanism of combustion wave with rotating propagation, provide theoretical and experimental fundamentals to understand process of the ignition and initiation in spiral/annular detonation chambers, and present optimization method for the design of initiation section in spiral detonation chamber.

螺旋爆震室和环形爆震室分别是脉冲爆震推进和连续旋转爆震推进中很有工程应用价值的爆震燃烧实现装置，而为实现爆震燃烧，爆燃向爆震转变的间接起爆方式是未来发展方向。对于前述的两种爆震室，燃烧波都是旋转传播的，这就涉及到一个共同的科学问题，即燃烧波旋转传播过程中的爆燃向爆震转变机制，当前有关该方面的研究还处于探索研究阶段。本项目拟针对此开展理论及试验研究，首先研究弯曲段内火焰传播特性，获得爆震触发条件形成阶段弯曲段实现火焰加速的内在机制及条件；然后研究爆震触发阶段中弯曲段内激波与火焰间相互作用及耦合机制；在此基础上，基于螺旋型管道，研究点火后管内燃烧模式的连续演化，总结归纳燃烧波旋转传播过程中的爆燃向爆震转变机制，进而为理解螺旋/环形爆震室内的点火起爆过程提供理论及试验基础，同时形成螺旋爆震室点火起爆段结构优化设计方法。

螺旋爆震室和环形爆震室分别是脉冲爆震推进和连续旋转爆震推进中很有工程应用价值的爆震燃烧实现装置，而为实现爆震燃烧，采用低点火能量以爆燃向爆震转变（deflagration to detonation transition，简称DDT）的间接起爆方式实现爆震燃烧是未来发展方向。对于前述的两种爆震室，燃烧波在爆震室内都是旋转传播的，这就涉及到一个共同的科学问题，即燃烧波旋转传播过程中的爆燃向爆震转变机制。针对该问题，本项目对各种曲率弯曲管道中火焰传播特性及DDT特性开展研究，在获得大量试验数据基础上，结合数值模拟，总结分析了燃烧波旋转传播的规律特性及影响因素，获得了这一过程中火焰演化的内在机制。具体包括：（1）通过对两种不同结构螺旋管道内点火后压力波的传播特性及DDT特性开展研究，发现螺旋管道内的DDT特性与无量纲长度有关，这为螺旋爆震室设计方法的提出提供了依据；（2）通过对90度、360度及720度弯曲段内火焰传播的数值模拟研究，获得了弯曲段内火焰发展、加速的流场分布及特性，这对理解试验中存在的某些现象提供了指导性依据；（3）通过外径256mm+内径216mm环形通道内低速火焰传播及燃烧波旋转传播过程中DDT特性的研究，基于高速摄影，获得了环段内燃烧模式的连续演化过程，发现了其与直管中的不同，并获得了其DDT机制；（4）通过对三种不同曲率环形通道内的DDT特性开展研究，获得了曲率影响规律，进一步加深了对DDT机制的理解，为螺旋爆震室、环形连续爆震室及螺旋预爆管的构型设计提供了理论依据；（5）通过在平面环形管道单侧开孔，获得了侧向稀疏对DDT过程的影响特性，同时发现侧向开孔加速DDT过程的新现象，这为新型触爆装置的设计提供了新的技术思路。