Collaborative Research: Fuel Droplet Disruption under Locally Supersonic Conditions

合作研究：局部超音速条件下的燃料液滴破裂

• 批准号: 0853396
• 负责人: Gretar Tryggvason
• 金额: $ 5万
• 依托单位: Worcester Polytechnic Institute
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0853396&HistoricalAwards=false
• 关键词: Collaborative; Research; Fuel; Droplet; Disruption

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).0853817/0853396Hermanson/TryggvasonThis preliminary experimental and computational research program will study the physical mechanisms of disruption and vaporization of liquid droplets in supersonic flow. These mechanisms include the deformation of the droplet due to aerodynamic forces, the inertial instability associated with droplet acceleration, and shear instability due to the high-speed flow across the droplet surface. An additional instability can result from the rapid evaporation that can result from the droplet fluid becoming superheated due to the low static pressure in the test section. The action of these mechanisms will be systematically studied by varying both the flow and thermal boundary conditions, including the Mach number relative to the droplet and the liquid composition. The possible existence of optimum combinations of parameters, such as droplet size, vapor pressure, and compressible free-stream conditions for the most rapid droplet disruption and vaporization will be explored. The original and potentially transformative aspects of this research stem from the combination of locally supersonic conditions with potential liquid superheating, which explores a practically important regime of droplet disruption that has not been examined in depth or in a systematic fashion to date. Droplets will be injected into supersonic flow using small-scale supersonic wind tunnels at the University of Washington (UW). A droplet-on-demand generator will produce monodisperse droplets sufficiently small that the droplets will not disrupt too quickly, but sufficiently large so that the droplets will "lag" the supersonic airflow to create compressible conditions relative to the droplet. Different test section geometries will produce droplets with both subsonic and supersonic Mach numbers relative to the surrounding flow. Diagnostic techniques will include planar laser-induced fluorescence (PLIF), spark schlieren/shadowgraph imaging, double-pulsed laser velocity measurement, and direct photography. These techniques will provide detailed knowledge of the droplet deformation/disruption, the dispersion of the expelled vapor, the droplet acceleration, the compressible flow field near the droplet, and the features of the interfacial instabilities. The computational modeling at Worcester Polytechnic Institute (WPI) will employ a finite volume/front-tracking method capable of simulating droplet deformation and explosive evaporation under compressible flow conditions. The simulations will be conducted synergistically with the experiments, using flow information from the experiments to guide the development and implementation of the numerical modeling. In turn, the numerical simulations will serve both to guide the conduct of the experiments as well as to help interpret the experimental results by providing key information not readily accessible by the experiments, such as the pressure variation in the vicinity of the droplets and the rate of vaporization. This research topic has applications to a number of practically important problems involving the injection of liquids in high-speed flows, including supersonic combustion ramjets (scramjets), pulsed detonation engines, re-entry body cooling, and surface erosion in high-speed flows. Such applications are impacted critically by the nature of droplet disruption and vaporization mechanisms of the liquid fuel droplets to be studied. This research will also directly impact education. The planar laser induced fluorescence and pulsed-laser droplet/particle velocity measurement techniques introduced into the undergraduate curriculum through existing experimental methods courses at the UW. Similarly, the numerical work will lead to examples that will be utilized as classroom examples at WPI. Undergraduate students will also participate directly in carrying out the research. The graduate students will actively participate in the undergraduate component of the program by serving, under faculty supervision, in the role of "grant monitor" for the undergraduate component of the research. Lastly, the co-PIs will recruit qualified and interested members of under-represented groups to conduct research at the University of Washington and at Worcester Polytechnic Institute.

该奖项是根据2009年美国复苏和再投资法案（公法111 - 5）资助的。0853817/0853396Hermanson/Tryggvason这个初步的实验和计算研究计划将研究超音速流中液滴的破坏和蒸发的物理机制。这些机制包括由于空气动力引起的液滴变形、与液滴加速相关的惯性不稳定性以及由于高速流过液滴表面引起的剪切不稳定性。另外的不稳定性可由快速蒸发引起，该快速蒸发可由液滴流体由于测试段中的低静压而变得过热引起。这些机制的作用将通过改变流动和热边界条件（包括相对于液滴和液体成分的马赫数）来系统地研究。将探讨可能存在的最佳参数组合，如液滴大小，蒸汽压，和可压缩的自由流条件下最快速的液滴破裂和蒸发。这项研究的原始和潜在的变革方面源于局部超音速条件与潜在的液体过热的结合，它探索了一个实际上重要的液滴中断制度，迄今为止还没有深入或系统地研究过。在华盛顿大学（UW），将使用小型超音速风洞将液滴注入超音速气流。按需液滴发生器将产生足够小的单分散液滴，使得液滴不会太快地破裂，但是足够大，使得液滴将“滞后”超音速气流以产生相对于液滴的可压缩条件。不同的试验段几何形状将产生相对于周围气流具有亚音速和超音速马赫数的液滴。诊断技术将包括平面激光诱导荧光（PLIF），火花纹影/阴影成像，双脉冲激光速度测量和直接摄影。这些技术将提供详细的知识的液滴变形/中断，排出的蒸汽的分散，液滴加速度，液滴附近的可压缩流场，和界面不稳定性的特征。伍斯特理工学院（WPI）的计算建模将采用有限体积/前沿跟踪方法，能够模拟可压缩流动条件下的液滴变形和爆炸性蒸发。模拟将与实验协同进行，使用实验中的流动信息来指导数值模拟的开发和实施。反过来，数值模拟将有助于指导实验的进行，以及通过提供实验不易获得的关键信息（例如液滴附近的压力变化和蒸发速率）来帮助解释实验结果。本研究课题已应用到一些实际上重要的问题，包括喷射液体在高速流，包括超音速燃烧冲压发动机（scramjet），脉冲爆震发动机，再入体冷却，和表面腐蚀在高速流。这些应用受到待研究的液体燃料液滴的液滴破裂和蒸发机制的性质的严重影响。这项研究也将直接影响教育。平面激光诱导荧光和脉冲激光液滴/颗粒速度测量技术通过华盛顿大学现有的实验方法课程引入本科课程。同样，数字工作将导致将被用作WPI课堂例子的例子。本科生也将直接参与开展研究。研究生将积极参与该计划的本科组成部分，在教师的监督下，在研究的本科组成部分的“补助金监督”的作用。最后，共同研究所将从代表性不足的群体中招募合格和感兴趣的成员，在华盛顿大学和伍斯特理工学院进行研究。