• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >A method for aircraft afterburner combustion without flameholders .
【24h】

A method for aircraft afterburner combustion without flameholders .

机译：没有火焰保持器的飞机加力燃烧方法。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

State of the art aircraft afterburners employ spray bars to inject fuel and flameholders to stabilize the combustion process. Such afterburner designs significantly increase the length (and thus weight), pressure losses, and observability of the engine. This thesis presents a feasibility study of a compact 'prime and trigger' (PAT) afterburner concept that eliminates the fuel spray bars and flameholders and, thus, eliminates the above-mentioned problems. In this concept, afterburner fuel is injected just upstream or in between the turbine stages. As the fuel travels through the turbine stages, it evaporates, mixes with the bulk flow, and undergoes some chemical reactions without any significant heat release, a process referred to as 'priming'. Downstream of the turbine stages, combustion could take place through autoignition. However, if fuel autoignition does not occur or if autoignition does not produce a combustion zone that is stable and highly efficient, then a low power pilot, or 'trigger', can be used to control the combustion process. The envisioned trigger for the PAT concept is a jet of product gas from ultra-rich hydrocarbon/air combustion that is injected through the afterburner liner. This 'partial oxidation' (POx) gas, which consists mostly of H2, CO, and diluents, rapidly produces radicals and heat that accelerate the autoignition of the primed mixture and, thus, provide an anchor point for the afterburner combustion process.;The objective of this research was to demonstrate the feasibility of the PAT concept by showing that (1) combustion of fuel injected within or upstream of turbine stages can occur only downstream of the turbine stages, and (2) the combustion zone is compact, stable and efficient. This was accomplished using two experimental facilities, a developed theoretical model, and Chemkin simulations. The first facility, termed the Afterburner Facility (AF), simulated the bulk flow temperature, velocity and O2 content through a turbojet combustor, turbine stage and afterburner. To model the PAT concept, Jet-A was injected upstream of the simulated turbine stage and a H2 jet was used to trigger the primed Jet-A combustion process downstream of the turbine stage. H2 was used because POx gas was not available for experiments. The second facility, termed the Propane Autoignition Combustor (PAC), was essentially a scaled-down, simplified version of the AF. The PAC experiments focused on the trigger stage of the PAT concept, using H 2 in lieu of POx gas and employing measurement techniques that were in some ways more detailed than in the AF experiments. The developed model simulated the physics of fuel priming in the AF and predicted the Jet-A autoignition location. It was used to predict and interpret the AF results and to study the feasibility of the PAT concept at pressures outside the AF operating range. Finally, the Chemkin simulations were used to examine the effect of several POx gas compositions on the Jet-A/vitiated-air autoignition process; to compare the POx and H2 triggers; and to explore several reasons for why POx gas and H2 are suitable trigger mechanisms.;he experimental, theoretical, and numerical results obtained in this investigation indicated that the PAT concept provides a feasible approach to afterburner combustion. The experiments in the AF showed that the ignition delay of Jet-A is sufficiently long to allow fuel injection within turbine stages without significant heat release upstream of the afterburner. In the AF experiments without the H2 trigger, Jet-A combustion was achieved through autoignition; however, the autoignition combustion zone exhibited large axial fluctuations and low combustion efficiency. The H2 trigger was able to shift the combustion zone upstream, make it more compact, reduce fluctuations in its axial position, and raise the combustion efficiency to nearly 100%. The PAC experiments also showed that a H2 trigger can shift the combustion zone upstream, make it more compact, and increase the combustion efficiency. The PAC results were obtained with lower O 2 content and higher equivalence ratios than in the AF. Therefore, the combined AF and PAC results suggested that the PAT concept is feasible over a wide range of operating conditions. The developed model showed good agreement with the AF results. It also predicted that the PAT concept is feasible at bulk flow pressures outside the AF operating range. Finally, the Chemkin results showed that both the H2 and POx gas triggers can significantly reduce the ignition delay time of primed Jet-A/vitiated air mixtures. Thus, POx gas is a suitable trigger for the PAT concept and should be tested in future experimental investigations.
机译：先进的飞机加力燃烧器采用喷杆喷射燃料和火焰保持器，以稳定燃烧过程。这样的加力燃烧器设计显着增加了发动机的长度（并因此增加了重量），压力损失和可观察性。本文提出了紧凑的“启动和起动”（PAT）加力燃烧室概念的可行性研究，该方案​​消除了燃油喷杆和火焰保持器，从而消除了上述问题。在此概念中，加力燃烧器燃料正好在涡轮级的上游或中间注入。当燃料通过涡轮级时，它会蒸发，与大流量混合并进行一些化学反应而没有任何明显的热量释放，这一过程称为“引燃”。在涡轮级的下游，燃烧可通过自燃发生。但是，如果没有发生燃料自燃，或者自燃不会产生稳定且高效的燃烧区，则可以使用低功率引燃器或“触发器”来控制燃烧过程。 PAT概念的预想触发器是来自超富碳氢化合物/空气燃烧的产物气体射流，该气体通过加力燃烧室衬套注入。这种主要由H2，CO和稀释剂组成的``部分氧化''（POx）气体会迅速产生自由基和热量，从而加速灌注混合物的自燃，从而为加力燃烧器的燃烧过程提供了一个固定点。这项研究的目的是通过证明（1）在涡轮级内或涡轮级上游喷射的燃料燃烧只能在涡轮级的下游进行燃烧，以及（2）燃烧区紧凑，稳定且燃烧，来证明PAT概念的可行性。高效。这是使用两个实验设备，一个完善的理论模型和Chemkin模拟来完成的。第一个设施称为加力燃烧室设施（AF），它通过涡轮喷气燃烧器，涡轮级和加力燃烧室模拟了总流量温度，速度和O2含量。为了模拟PAT概念，将Jet-A喷射到模拟涡轮级的上游，并使用H2射流触发涡轮级下游的起动式Jet-A燃烧过程。使用H2是因为无法使用POx气体进行实验。第二种设施称为丙烷自动点火燃烧器（PAC），本质上是AF的缩小版简化版。 PAC实验着重于PAT概念的触发阶段，使用H 2代替POx气体，并采用比AF实验更详细的测量技术。所开发的模型模拟了AF中燃料注油的物理过程，并预测了Jet-A自动点火的位置。它被用来预测和解释自动对焦的结果，并研究在自动对焦操作范围以外的压力下PAT概念的可行性。最后，Chemkin模拟用于检查几种POx气体成分对Jet-A /通风空气自动点火过程的影响。比较POx和H2触发器；并探究了为什么POx气体和H2是合适的触发机制的几个原因。本次研究获得的实验，理论和数值结果表明，PAT概念为加力燃烧提供了一种可行的方法。 AF中的实验表明，Jet-A的点火延迟足够长，可以在涡轮级内进行燃料喷射，而在加力燃烧器上游没有明显的热量释放。在没有H2触发的AF实验中，Jet-A燃烧是通过自动点火实现的。但是，自燃燃烧区的轴向波动大，燃烧效率低。 H2扳机能够将燃烧区向上游移动，使其更加紧凑，减少轴向位置的波动，并将燃烧效率提高到近100％。 PAC实验还表明，H2触发器可以使燃烧区向上游移动，使其更加紧凑，并提高燃烧效率。与AF相比，获得的PAC结果具有更低的O 2含量和更高的当量比。因此，AF和PAC的综合结果表明，PAT概念在广泛的工作条件下都是可行的。所开发的模型与自动对焦结果显示出良好的一致性。它还预测，PAT概念在AF工作范围以外的大流量压力下是可行的。最后，Chemkin结果表明，H2和POx气体触发器均可显着减少灌注了Jet-A /已用空气混合物的点火延迟时间。因此，POx气体是PAT概念的合适触发因素，应在以后的实验研究中进行测试。

著录项

  • 作者

    Birmaher, Shai.;

  • 作者单位

    Georgia Institute of Technology.;

  • 授予单位 Georgia Institute of Technology.;
  • 学科 Engineering Aerospace.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 209 p.
  • 总页数 209
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 航空、航天技术的研究与探索;
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号