• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Numerical study of innovative scramjet inlets coupled to combustors using hydrocarbon-air mixture.
【24h】

Numerical study of innovative scramjet inlets coupled to combustors using hydrocarbon-air mixture.

机译：使用碳氢化合物-空气混合物与燃烧室连接的新型超燃冲压发动机进气道的数值研究。

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

The research objective is to use high-fidelity multi-physics Computational Fluid Dynamics (CFD) analysis to characterize 3-D scramjet flowfields in two novel streamline traced circular configurations without axisymmetric profiles. This work builds on a body of research conducted over the past several years. In addition, this research provides the modeling and simulation support, prior to ground (wind tunnel) and flight experiment programs. Two innovative inlets, Jaws and Scoop, are analyzed and compared to a Baseline inlet, a current state of the art rectangular inlet used as a baseline for on/off-design conditions. The flight trajectory conditions selected were Mach 6 and a dynamic pressure of 1,500 psf (71.82 kPa), corresponding to a static pressure of 43.7 psf (2.09 kPa) and temperature of 400.8 R° (222.67 C°). All inlets are designed for equal flight conditions, equal contraction ratios and exit cross-sectional areas, thus facilitating their comparison and integration to a common combustor design.;Analysis of these hypersonic inlets was performed to investigate distortion effects downstream in common generic combustors. These combustors include a single cavity acting as flame holder and strategically positioned fuel injection ports. This research not only seeks to identify the most successful integrated scramjet inlet/combustor design, but also investigates the flow physics and quantifies the integrated performance impact of the two novel scramjet inlet designs. It contributes to the hypersonic air-breathing community by providing analysis and predictions on directly-coupled combustor numerical experiments for developing pioneering inlets or nozzles for scramjets.;Several validations and verifications of General Propulsion Analysis Chemical-kinetic and Two-phase (GPACT), the CFD tool, were conducted throughout the research. In addition, this study uses 13 gaseous species and 20 reactions for an Ethylene/air finite-rate chemical model. The key conclusions of this research are: (1) Flow distortion in the innovative inlets is similar to some of the distortion in the Baseline inlet, despite design differences. In both innovative inlets, the resulting flowfield distortions were due to shock boundary layer interactions similar to those found in the Baseline. The Baseline and Jaws performance attributes are stronger than Scoop, but Jaws accomplishes this while eradicating the cowl lip interaction, and lessening the total drag and spillage penalties. (2) The innovative inlets work best on-design, whereas for off-design, the traditional inlet yields a higher performance. Although the innovative inlets' designs mitigated some of the issues encountered in traditional configurations, they underperform at off-design conditions. The strategy used in Jaws was less prone to interaction with the near wall flow, and yields lesser pressure losses and higher efficiency at on-design conditions compared to the others. In general, the overall values for Scoop seem lowest of all due to lesser entrainment. Its drag coefficient and thrust to mass capture ratios are higher than the Baseline configuration. (3) Early pressure losses and flow distortions actually aid downstream combustion in all cases. Although interactions captured by the viscous simulations for the on-design conditions increase losses in the inlets, they enhance turbulence in the isolator, favoring the mixing of air and fuel, and improving the overall factor of the system. Jaws inlet demonstrates the most valuable design with higher performance, but its factor later in the combustor drops relative to its rectangular counterpart. (4) A parametric study of the location and direction of injection is conducted to select the configuration for fuel penetration, mixing factor (factor) and other combustion qualities. Although the trends observed with and without chemical reactions are the same, the former yields roughly 10% higher mixing factor. Unlike at frozen conditions, when chemical reactions are considered, a high compression area was observed upstream of the cavity, not present when modeling Jaws. The upstream reactions from the cavity have a significant impact on the development of the shear layers and downstream development of the entire combustion. (5) Steady and unsteady simulations are conducted to characterize the ignition process, flame anchoring and flashback effects. This unsteadiness enlarges the circulation region in and around the cavity, allowing the reactions to propagate forward through the shear layer, and increases the mixing factor. In Scoop, these effects are exacerbated due to the thicker low energy profile surrounding the walls and most of the lower section of the combustor. In the steady assumptions, the forward reactions and their effects are positioned farthest upstream, closest to the combustor entrance. (6) Unsteady Reynolds Average Navier-Stokes (URANS) and Large Eddy Simulation (LES) modeling are compared to explore overall flow structure and for comparison of individual numerical methods. In URANS, the flashback effects are midway between the entrance and the step, whereas in LES, this effect is near the edge of the step in addition to yielding a higher combustion factor. Thus, the turbulence model and inflow assumptions can critically affect the total outcome of such devices.
机译：研究目的是使用高保真多物理场计算流体动力学（CFD）分析来表征两种新颖的流线形圆形轮廓中的3-D超燃冲压流场，而没有轴对称轮廓。这项工作建立在过去几年的大量研究基础之上。此外，该研究还为地面（风洞）和飞行实验程序提供了建模和仿真支持。分析了两个创新的进给口（钳口和铲状），并将其与Baseline进样口进行比较，Baseline进样口是当前最先进的矩形进样口，用作开/关设计条件的基线。所选的飞行轨迹条件为6马赫，动态压力为1,500 psf（71.82 kPa），对应于43.7 psf（2.09 kPa）的静态压力和400.8 R°（222.67 C°）的温度。所有进气口均设计为具有相同的飞行条件，相同的压缩比和出口横截面面积，从而便于将它们与通用燃烧器设计进行比较和集成。;对这些超音速进气口进行了分析，以研究普通通用燃烧器下游的畸变效应。这些燃烧器包括一个用作火焰保持器的腔体和策略性地定位的燃料喷射口。这项研究不仅试图确定最成功的一体式超燃冲压进气/燃烧器设计，而且还研究了流动物理学并量化了两种新型超燃喷射进气设计对综合性能的影响。它通过对直接耦合燃烧室数值实验进行分析和预测，以开发超燃冲压发动机的先驱进气口或喷嘴，为高超声速空气呼吸界做出了贡献;通用推进分析化学动力学和两相（GPACT）的多次验证和验证， CFD工具在整个研究过程中进行。此外，本研究使用13种气态物质和20种反应来建立乙烯/空气有限速率化学模型。这项研究的主要结论是：（1）尽管设计有所不同，但创新型进样口的流量畸变与基线进样口的某些畸变相似。在两个创新的进样口中，产生的流场变形均是由于与基准线相似的冲击边界层相互作用所致。 “基线”和“下颌”性能属性比“铲斗”更强，但是“下颌”在消除前围唇相互作用的同时减少了总阻力和溢出损失，从而达到了这一目的。 （2）创新的进气口在设计时效果最好，而在非设计时，传统的进气口具有更高的性能。尽管创新的进气口设计减轻了传统配置中遇到的一些问题，但它们在非设计条件下表现不佳。在下颌中使用的策略较不易于与近壁流相互作用，并且与其他方法相比，在设计条件下产生的压力损失较小，效率更高。通常，由于夹带较少，Scoop的整体值似乎最低。它的阻力系数和推力与质量捕获比均高于“基线”配置。 （3）在所有情况下，早期的压力损失和流量畸变实际上都有助于下游燃烧。尽管针对设计条件的粘性模拟所捕获的相互作用会增加进气口的损失，但它们会增加隔离器中的湍流，有利于空气和燃料的混合，并改善了系统的整体因素。钳口展示了最有价值的设计，具有更高的性能，但其在燃烧室中的影响却相对于其矩形对应物下降。 （4）对喷射的位置和方向进行了参数研究，以选择燃料渗透，混合因子（因子）和其他燃烧质量的配置。尽管在有和没有化学反应的情况下观察到的趋势都是相同的，但前者的混合因子提高了约10％。与在冻结条件下不同，当考虑化学反应时，在腔体上游观察到高压缩区域，而在模拟下颌时则不存在。空腔的上游反应对剪切层的发展和整个燃烧的下游发展有重大影响。 （5）进行稳态和非稳态模拟以表征点火过程，火焰锚定和回火效应。这种不稳定增加了空腔内及其周围的循环区域，使反应向前传播通过剪切层，并增加了混合系数。在Scoop中，由于围绕燃烧室壁和大部分下部的较厚的低能分布，这些影响更加严重。在稳定的假设中，正向反应及其影响位于最上游，最靠近燃烧室入口。 （6）比较了非稳态雷诺平均Navier-Stokes（URANS）模型和大涡模拟（LES）建模，以探索整体流动结构并比较各个数值方法。在URANS中，回火效应位于入口和台阶之间的中间，而在LES中，该效应除了产生更高的燃烧因子外，还靠近台阶的边缘。因此，湍流模型和入流假设会严重影响此类设备的总体结果。

著录项

  • 作者

    Malo-Molina, Faure Joel.;

  • 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 2010
  • 页码 272 p.
  • 总页数 272
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 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