微灌滴头平角齿形微通道流动实验研究

采用Micro—PIV技术，以边长800 μm方形截面平角齿形微灌滴头内流微通道为对象，对微通道内流体运动进行了测量。实验使用lOx显微物镜、14位灰阶PC01600相机、3μm荧光示踪粒子和仅允许610nm红光透过的滤光镜相配合、获取了清晰的粒子图像，解决了相机与PIV系统的匹配问题，提高了图像信噪比。在图像处理中使用多次测量取平均的方法消除示踪粒子的布朗运动影响，运用系综互相关算法获取流场速度分布和流线图。实验发现微通道内各齿间流动结构基本一致，即通道内流充分发展后是一种周期性流动；通道顶角和转角内侧存在低速涡旋区，其涡旋结构和尺度随时间和Re变化而变化；颗粒在低速涡旋区易发生沉积，是造成堵塞的主要原因。

Experimental research on flow in jagged channel with flat top of micro-irrigation emitter

Using micro-fluidic particle image velocimetry （micro-PIV） technique, the paper investigated measurements for the square micro-channel with side lengths of 800 μm. To attain distinct particle image, solve the problems of matching camera with PIV system and improve the image＇s signal-to-noise ratio, the research adopted 10x microscope, 14-bit CCD camera system, 3μm fluorescent particles and filter lens that only allow 610nm red light penetration. In the image processing, Brownian motion＇s impact on tracing particles was eliminated by the average of images. Using ensemble correlation arithmetic acquired velocity distribution and velocity streamline. The results show that jags＇ flow structure is basically consistent inside the micro-channel. The fully developed internal flow in the channel is a cycling movement. There exists low speed vortex area in the micro-channel＇s flat top and corner, whose vortex structure and size depend on time and Reynolds number. The particles are vulnerable to deposit in the low-speed vortex area, which proves the main factor for block.