High-speed echographic particle image velocimetry (echo-PIV)

高速回波粒子图像测速 (echo-PIV)

• 批准号: RGPIN-2015-04217
• 负责人: Garcia, Damien
• 金额: $ 1.82万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612837
• 关键词: speed; echographic; particle; image; velocimetry

1) AT A GLANCE Echo-PIV (echographic particle image velocimetry) is limited to low frame rates, which reduces flow measurement capability. We will develop and validate high-speed echo-PIV offering up to a 100-fold increase in sampling rate. 2) CONTEXT: OPTICAL vs. ECHOGRAPHIC PIV Particle image velocimetry (PIV) is a non-intrusive optical technique of flow visualization for experimental fluid dynamics. PIV takes two closely timed images and estimates the distance that tracer particles travelled within this time. From the known time interval and the measured displacements, the instantaneous velocity fields are calculated, from which several flow properties can be deduced. In optical PIV, the seeding particles are illuminated with short-pulse-laser light to freeze the motion. Optical PIV is thus only applicable with materials transparent to light. Echo-PIV (echographic PIV) is based on the same principles as optical PIV. Instead of laser light illumination, the seeding particles are insonified with ultrasound waves. Ultrasound backscattering generates speckle patterns which can be tracked to deduce the displacements from one image to the next one. Echo-PIV has been of high interest in blood flow investigation. Echo-PIV, however, is hampered by conventional ultrasound imaging which offers a frame rate much smaller than optical PIV. Indeed, conventional ultrasound imaging emits successive focused beams to fully cover the region of interest. Typically, 128 emissions are required to obtain one single image. The objective of this research project is to use ultrafast ultrasound to produce high-speed echo-PIV working at frame rates up to 10,000 fps. High-speed echo-PIV has the potential to enlarge the family of fluid measurement systems. 3) METHODS To test high-speed echo-PIV, we will carry out velocity measurements in well-controlled Womersley and vortical flows, as well as in a pulse heart duplicator (ViVitro). The ViVitro system is compatible with both ultrasound and optical PIV. Pulsatile Womersley flows will be generated in a cylindrical pipe with a piston pump. From the known flow rate (given by an electromagnetic flowmeter) and pipe radius, the theoretical velocity profiles will be calculated using the Womersley equation. Three-dimensional vortical flows will be also created in a Plexiglas square box, transparent both to light and ultrasound, with a magnetic stirrer. In addition, to test high-speed echo-PIV with complex flow patterns, we will investigate intraventricular filling in the heart duplicator. The velocities will be measured by optical three-dimensional volumetric PIV (V3V-9800, TSI Inc.). In the different experimental setups, the velocities determined by high-speed echo-PIV will be compared with the ground-truth velocities, given by theory and/or optical PIV. Pixelwise comparisons will be performed on several planes and for different flow conditions.

1)一目了然 ECHO-PIV(回声粒子图像测速仪)仅限于低帧速率，这降低了流量测量能力。我们将开发和验证高速ECHO-PIV，提供高达100倍的采样率。 2)背景：光学PIV与回声PIV 粒子图像测速技术(PIV)是一种用于实验流体力学的非侵入式光学流动显示技术。PIV拍摄了两张时间很近的图像，并估计了示踪剂粒子在这段时间内行驶的距离。根据已知的时间间隔和测量的位移，计算出瞬时速度场，由此可以推断出几种流动特性。在光学PIV中，用短脉冲激光照射种子粒子来冻结运动。因此，光学PIV仅适用于对光透明的材料。 ECHO-PIV(回声PIV)基于与光学PIV相同的原理。播种粒子不是用激光照射，而是用超声波辐射。超声背向散射产生的散斑图案可以被跟踪，以推断从一幅图像到下一幅图像的位移。ECHO-PIV在血流研究中引起了极大的兴趣。然而，ECHO-PIV受到传统超声成像的阻碍，后者提供的帧速率比光学PIV小得多。事实上，传统的超声成像会发出连续的聚焦波束来完全覆盖感兴趣的区域。通常，需要128次发射才能获得一张图像。 该研究项目的目标是使用超快超声波产生工作在10000帧/秒的高速ECHO-PIV。高速ECHO-PIV具有扩大流体测量系统家族的潜力。 3)方法 为了测试高速ECHO-PIV，我们将在控制良好的沃斯利和涡流中进行速度测量，以及在脉搏心脏复制器(ViVitro)中进行速度测量。ViVitro系统兼容超声波和光学PIV。脉动沃姆斯利流动将在带有活塞泵的圆柱管中产生。根据已知的流量(由电磁流量计给出)和管道半径，将使用沃姆斯利方程计算理论速度分布。利用磁力搅拌器，还将在对光和超声波都透明的正方形有机玻璃盒子中创建三维涡流。此外，为了测试具有复杂血流模式的高速ECHO-PIV，我们将研究心脏复制器的室内充盈情况。速度将由光学三维体积PIV(V3V-9800，TSI Inc.)测量。在不同的实验装置中，由高速ECHO-PIV确定的速度将与由理论和/或光学PIV给出的地面真实速度进行比较。将在不同的流动条件下，在多个平面上进行像素比较。