Technology Development on Control of the Low Reynolds Number Flow by Using Micro Jets

本课题的目的是开发一种利用脉动微射流控制低雷诺数流动的系统。针对立体微粒子图像测速（PIV），对系统进行了改进，以防止光学器件的失焦。该系统在图像、激光光源的闪光定时和射流脉动之间具有时间同步。利用帧率为6000fps的高速摄像机，得到了射流的速度和涡量，特别是射流锋面的速度和涡量，阐明了射流锋面对动态PIV的抽气效应。在低雷诺数范围内，将合成射流和脉冲射流以及连续射流注入静止空气或二维通道流中。研究了射流脉动频率、射流直径和射流与主流速度比对射流静态和动态特性的影响。与静止空气中的脉冲射流和连续射流相比，在更下游的区域观察到合成射流的痕迹。当射流注入到充分发育的通道流中时，发现合成射流对促进流体混合是有效的。然后，本课题以脉动微射流作为微驱动器，构建了用于控制低雷诺数流动的MEMS系统。在未来的项目中，由于本项目获得了MEMS设计数据库，将采用具有先进微传感器和执行器的流体MEMS。这也将有可能开发与器件制造阶段快速同步的流体MEMS。此外，将从器械应用的角度对器械制造问题给出有效的回答和建议。因此，本文的研究成果对低雷诺数流动控制技术在未来微流体应用中的发展具有重要意义。

The objective of the present project is to develop a control system of the low Reynolds number flow by using a micro jet with pulsation. As to the stereo micro Particle Image Velocimetry (PIV), the system is improved to prevent de-focusing by an optical device. The system has a time synchronization between the image, flash timing of the Laser light source and the jet pulsation. By using the high speed video camera with frame rate of 6000 fps, the velocity and the vorticity of the jet, in particular the jet front, are obtained to clarify the puff effect of the jet front as to the dynamic PIV. The synthetic jet and the pulsed jet as well as the continuous jet are injected into a still air or a two-dimensional channel flow in the low Reynolds number range. The effect of pulsation frequency of the jet, the jet diameter and the jet to main-stream velocity ratio on the static and dynamic characteristics of the jet are investigated. A trace of the synthetic jet is observed further downstream region compared with the pulsed and continuous jet in the still air. When the jet is injected into the fully developed channel flow, the synthetic jet is found to be effective for fluid mixing promotion. Then, the MEMS system is constructed for the control of the low Reynolds number flow by using the micro jet with pulsation as a micro actuator in the present project. In the future project, fluidic MEMS with the advanced micro sensor and actuator will be employed because of the MEMS design database obtained in the present project. It will also possible to develop the fluidic MEMS quickly synchronized with the device manufacturing phase. Furthermore, an effective answer and advice for the device manufacturing problems will be made from the view point of the device application. Therefore, the present fruitful results make much contribution to the development of the control technology about the low Reynolds number flow in the future micro fluidic application.