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Design and optimization of a deflagration to detonation transition (ddt) section.

机译：爆燃到爆轰过渡（ddt）部分的设计和优化。

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摘要

Throughout the previous century, hydrocarbon-fueled engines have used and optimized the `traditional' combustion process called deflagration (subsonic combustion). An alternative form of combustion, detonation (supersonic combustion), can increase the thermal efficiency of the process by anywhere from 20 - 50%. Even though several authors have studied detonation waves since the 1890's and a plethora of papers and books have been published, it was not until 2008 that the first detonation-powered flight took place. It lasted for 10 seconds at 100 ft. altitude. Achieving detonation presents its own challenges: some fuels are not prone to detonate, severe vibrations caused by the cyclic nature of the engine and its intense noise are some of the key areas that need further research. Also, to directly achieve detonation either a high-energy, bulky, ignition system is required, or the combustion chamber must be fairly long (5 ft. or more in some cases). In the latter method, a subsonic flame front accelerates within the combustion chamber until it reaches supersonic speeds, thus detonation is attained. This is called deflagration-todetonation transition (DDT). Previous papers and experiments have shown that obstacles, such as discs with an orifice, located inside the combustion chamber can shorten the distance required to achieve detonation. This paper describes a hands-on implementation of a DDT device. Different disc geometries inside the chamber alter the wave characteristics at the exit of the tube. Although detonation was reached only when using pure oxygen, testing identified an obstacle configuration for LPG and air mixtures that increased pressure and wave speed significantly when compared to baseline or other obstacle configurations. Mixtures of LPG and air were accelerated to Mach 0.96 in the downstream frame of reference, which would indicate a transition to detonation was close. Reasons for not achieving detonation may include poor fuel and oxidizer mixing, and/or the need for a longer DDT section.
机译：在整个上个世纪中，碳氢燃料发动机已经使用并优化了称为爆燃（亚音速燃烧）的“传统”燃烧过程。爆炸的另一种燃烧形式（爆震（超音速燃烧））可以使过程的热效率提高20％到50％。尽管自1890年代以来几位作者研究了爆炸波，并出版了许多论文和书籍，但直到2008年才进行了第一次由爆炸驱动的飞行。它在100英尺高的地方持续了10秒钟。实现爆轰面临着自己的挑战：某些燃料不易引爆，发动机循环特性及其强烈的噪音引起的剧烈振动是需要进一步研究的一些关键领域。另外，要直接实现爆轰，要么需要高能量，笨重的点火系统，要么燃烧室必须相当长（某些情况下为5英尺或更长）。在后一种方法中，亚音速火焰锋在燃烧室内加速，直到达到超音速为止，从而实现了爆炸。这称为爆燃-爆轰过渡（DDT）。先前的论文和实验表明，位于燃烧室内的障碍物（例如带孔的圆盘）可缩短实现爆轰所需的距离。本文介绍了DDT设备的动手实现。室内不同的圆盘几何形状会改变管子出口处的波动特性。尽管仅在使用纯氧时才发生爆炸，但测试发现，与基线或其他障碍物配置相比，LPG和空气混合物的障碍物配置显着增加了压力和波速。在下游参考系中，液化石油气和空气的混合物被加速至0.96马赫，这表明向爆炸的过渡已经接近。无法实现爆震的原因可能包括燃料和氧化剂混合不良，和/或需要更长的DDT区域。

著录项

  • 作者

    Romo, Francisco X.;

  • 作者单位

    Embry-Riddle Aeronautical University.;

  • 授予单位 Embry-Riddle Aeronautical University.;
  • 学科 Engineering Aerospace.
  • 学位 M.S.A.E.
  • 年度 2012
  • 页码 152 p.
  • 总页数 152
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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