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: 0853817
• 负责人: James Hermanson
• 金额: $ 8.5万
• 依托单位: University of Washington
• 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 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0853817&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《美国复苏与再投资法》（公法111-5）资助的。 0853817/0853396HERMANSON/TRYGGVASONITHIS THREMANTHIS TRYERIMINIal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而引起的液滴的变形，与液滴加速度相关的惯性不稳定以及由于横向液滴表面的高速流而引起的剪切不稳定性。由于测试部分中的静压低而导致的液滴液会产生过热，可能导致额外的不稳定。这些机制的作用将通过改变流量和热边界条件（包括相对于液滴和液体组成）的流量和热边界条件来系统地研究。将探索参数最佳组合的可能存在，例如液滴尺寸，蒸气压和可压缩的自由流条件，以实现最快的液滴破坏和蒸发。这项研究的原始且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，探索了实际上重要的液滴破坏方案，尚未以深入或系统的方式检查，迄今为止尚未以系统的方式进行检查。在华盛顿大学（UW）使用小规模的超音速风隧道，将液滴注入超音速流。液滴按需发电机会产生足够小的单分散液滴，以至于液滴不会太快破坏，但是足够大，以使液滴“落后”超音速气流，以创建相对于液滴的可压缩条件。不同的测试部分的几何形状将产生相对于周围流量的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的荧光（PLIF），Spark Schlieren/Shadowgraph Imaging，双脉冲激光速度测量和直接摄影。这些技术将提供有关液滴变形/破坏，驱动蒸气的分散，液滴加速度，液滴附近的可压缩流场以及界面不稳定的特征的详细知识。伍斯特理工学院（WPI）的计算建模将采用有限体积/前跟踪方法，能够在可压缩流条件下模拟液滴变形和爆炸性蒸发。模拟将使用实验中的流信息协同进行实验进行协同作用，以指导数值建模的开发和实施。反过来，数值模拟将既可以指导实验的进行，又可以通过提供实验不容易访问的关键信息来帮助解释实验结果，例如液滴附近的压力变化和汽化速率。该研究主题适用于许多实际重要的问题，这些问题涉及在高速流中注射液体，包括超音速燃烧挡板（Scramjets），脉冲爆炸引擎，重新进入身体冷却和高速流中的表面侵蚀。这些应用受到液滴破坏的性质和要研究的液体燃料液滴的蒸发机制的影响。这项研究还将直接影响教育。平面激光诱导荧光和脉冲激光液滴/粒子速度测量技术通过UW的现有实验方法课程引入了本科课程中。同样，数值工作将导致示例将被用作WPI的课堂示例。本科生还将直接参加研究。研究生将在教师的监督下为该研究的本科部分的“赠款监视器”发挥作用，从而积极参与该计划的本科组成部分。最后，共同案例将招募有资格的和有兴趣的成员，代表性不足的团体在华盛顿大学和伍斯特理工学院进行研究。