MRI: Development of a Multi-Camera Synthetic Aperture Technique for Measuring High-Speed, Unsteady, Three-Dimensional Velocity Flow Fields

该主要研究仪器（MRI）为开发用于测量高速、非定常、三维速度流场的多相机合成孔径技术提供资金。杨百翰大学（BYU）的定量流体成像研究小组由三个实验室和三个pi组成，专注于实验流体动力学，因为它涉及无数的多学科领域。实验室的研究人员奉行一种哲学，欢迎来自更广泛的大学社区内外的其他研究人员的参与。综合设施支持外部资助的研究项目，以及本科生和研究生动手教学实验室。这些实验室在研究项目上合作，并共享资源，以鼓励社区内的合作和友爱。该工具集专注于可视化和量化流体现象，其中对其行为的理解对于理解其基本物理特性至关重要。这些现象包括但不限于人类呼吸道流动模式、昆虫飞行空气动力学、物体的水-出-入、多相流、疏水表面相互作用和血流中的血栓形成。到目前为止，这些系统已经能够使用单相机2D PIV系统、热线测风或高速成像推断来研究。然而，该组织缺乏三维流动可视化系统和及时解析流场的能力。PI与麻省理工学院合作设计了一项新技术，使用几个高速摄像机从复杂的流体流动中提取速度。通过使用来自多个摄像机的多个视点，在三维空间中定量测量流中的速度。杨百翰大学计划的系统由10台高速摄像机和高速激光同步组成，以捕获瞬态体积流场图像数据。通过在数字领域对2D图像进行重组，可以为每个时间瞬间构建3D体，从而提供与视野（X-Y）一样深的体积(Z)的时间分辨信息，第三个优势是能够看到部分遮挡物周围，使我们能够分析密集的种子流体积。这项技术有可能在未来几年成为确定流体流动速度的标准。该系统克服了当前3D PIV的一些缺点，如有限的范围和分辨率以及低粒子播种密度。与现成的高速层析PIV系统成本大致相同，可以实现更大的面外尺寸和更大的播种密度，同时开发一种新的最先进的系统/技术，帮助教育和激励新一代学生。流体成像小组进行的研究是多学科的，跨越学院、部门和大学的界限，为化学、机械和土木工程以及物理、化学、生物和数学部门的教职员工和学生提供支持。仪器的发展将扩大单个研究项目的影响，允许对正在研究的物理现象进行更深入的了解。随着该技术通过专门的网站、出版物和外联活动在科学和工程社区中传播，该技术还将提高对未来项目的理解。3D合成孔径系统的开发也将有利于杨百翰大学校园内外的科学和工程的其他方面，特别是本科生的教育和经验。该系统的许多开发人员和用户将是从事本科研究的本科生。帮助开发这样一个工具将使本科生获得通常为更高学位的求职者保留的教育机会。杨百翰大学在这方面是独一无二的，而且学校非常重视本科生的研究。超过75%的机械工程专业毕业生追求更高的学位，使用拟议系统的经验将为研究生水平的研究和未来的职业生涯提供良好的培训。在杨百翰大学，最好的指导模式是教师、研究生和本科生组成协同研究团队。该设备还将集成到两个课程实验室中，将课程扩展到高速、3D方法和现实世界应用，同时强调使用多学科方法研究困难的科学和工程问题的好处。最后，开发的系统将成为一个具有深远多学科应用的高知名度系统，将通过校园外展活动吸引和招募代表性不足的学生进入STEM领域。

This Major Research Instrumentation (MRI) provides funding to develop a multi-camera synthetic aperture technique for measuring high-speed, unsteady, 3-D velocity flow fields. The quantitative fluids imaging research group at Brigham Young University (BYU) is a combination of three laboratories and three PIs focused on experimental fluid dynamics as it relates to a myriad of multidisciplinary areas. The laboratory researchers embrace a philosophy of welcoming participation from other researchers within the broader university community on and off campus. The combined facilities support externally funded research projects, as well as both undergraduate and graduate hands-on instructional laboratories. The laboratories work together on research projects and share resources in an effort to encourage collaboration and camaraderie within the community. The toolset is focused on visualizing and quantifying fluid phenomena where an understanding of their behavior is crucial to understanding their basic physics. The phenomena include, but are not limited to, human respiratory airway flow patterns, insect flight aerodynamics, water-exit-entry of objects, multiphase flows, hydrophobic surface interaction, and thrombosis growth in blood flow. Thus far these systems have able to be studied using single-camera 2D PIV systems, hot-wire anemometry, or inferences from high-speed imaging. However, the group lacks a 3D flow visualization system and the ability to resolve flow fields in time. A novel new technique designed by the PI, in collaboration with MIT, uses several high-speed cameras to extract velocities from complex fluid flows. Velocities in the flow are quantitatively measured in three dimensions by using several viewpoints from multiple cameras. The planned system at BYU consists of ten high-speed cameras synchronized with a high-speed laser to capture transient volumetric flow field image data. Through a recombination of the 2D mages in the digital realm a 3D volume can be constructed for each time instant, thus providing time-resolved information in volumes as deep (Z) as the field of view (X-Y), with the tertiary advantage of being able to see around partial occluders, allowing us to analyze densely seeded flow volumes. This technique has the potential to become the standard for determining velocities of fluid flows in the coming years. The system overcomes some of the current 3D PIV disadvantages such as limited range and resolution and low particle seeding densities. For roughly the same cost as an off-the-shelf high-speed tomographic PIV system, larger out-of-plane dimensions and larger seeding densities, can be achieved while developing a new state-of-the-art system/technology that helps educate and inspire a new generation of students.The research performed by the fluids imaging group is multidisciplinary and reaches across college, department, and university boundaries to support faculty, staff, and students from the Departments of Chemical, Mechanical and Civil Engineering as well as Physics, Chemistry, Biology and Mathematics. The instrumentation development will broaden the impact of the individual research projects by allowing the pursuit of a deeper understanding of the physical phenomena being studied. The technique will also improve understanding of future projects as the technique is disseminated among the scientific and engineering communities through a dedicated website, publication, and outreach activities. The development of the 3D Synthetic Aperture system will also benefit other aspects of science and engineering on and off the BYU campus, particularly undergraduate student education and experience. Many of the developers and users of the system will be undergraduates doing undergraduate research. Helping to develop a tool like this one will enable undergraduates to receive educational opportunities normally reserved for more advanced degree seekers. BYU is unique in this regard and a large institutional emphasis on undergraduate research exists. Over 75 percent of the graduates of the Mechanical Engineering program pursue advanced degrees, and experiences using the proposed system will provide excellent training for future impact in graduate level research and future careers. At BYU the best mentoring model combines faculty, graduate students, and undergraduates in synergistic research teams. The equipment will also be integrated into two course laboratories to extend the curriculum into high-speed, 3D methods and real world applications, while emphasizing the benefit of using multidisciplinary approaches to study difficult science and engineering problems. Finally, the developed system will be a high-profile system with far reaching multidisciplinary applications that will be leveraged to attract and recruit underrepresented students to STEM fields through outreach activities on campus.