DEVELOPMENT OF THE SYSTEM FOR MEASURING THREE DIMENSIONAL UNSTABLE FLOW IN MAGNETIC STORAGE DISKS

旋转圆盘间的不稳定流动最近被认为是与圆盘颤振、圆盘碰撞、热问题和粉尘行为有关的一个重要研究主题。针对这一问题，本文利用氢气泡法和图像增强技术，研制了一套三维速度场和不稳定流频率测量系统。我们按照以下步骤进行了实验：(1)实验装置的设计与制造，(2)驱动盘控制系统的设计与制造，(3)氢泡产生电路的设计与制造，(4)实验，(5)图像分析方法的开发，(6)图像分析软件的开发，(7)所开发系统的验证方法的开发。实验装置为COMPO…更多的是模拟裹尸布的亚克力圆柱体和两个平行旋转的玻璃盘。在两个圆盘的中间，我们安装了一根细长的不锈钢丝来产生氢气泡。这根电线的电是通过滑轨提供的。利用两个摄像头，一个是俯视的，一个是侧视的，由两个摄像头和录像机组成的图像合成装置，我们可以记录三维气泡运动的行为。最后，为了验证该系统的有效性，我们模拟了在两个旋转圆盘中间产生的单个气泡的运动。因此，我们认识到该系统对于从旋转坐标系中定量观察不稳定流动是有效的，但对于沿旋转轴方向的流动却不是有效的，因为作用在气泡上的浮力。较少

The unstable flow between two rotating disks has recently considered as an important research theme in connection with disk-flutter, disk-crash; thermal problems and the behavior of dusts. Only a few reports can be found on this topic because the flow is so complicated and has three dimensional structures.In this study, we developed a system for measuring three dimensional velocity fields and the frequency of the unstable flow by using hydrogen bubble method and image enhancement technique. We performed the project according to the following procedure; (1)Design and manufacturing of the experimental apparatus, (2)Design and manufacturing of the control system for driving disks, (3)Design and manufacturing of electric circuits for generating hydrogen bubbles, (4)Experiment, (5)Development of the method for image analysis, (6)Development of the software for image analysis, (7)Development of the verification method for the system developed in this study.The experimental apparatus is compo … More sed of the acrylic cylinder simulating the shroud and two parallel rotating glass disks. In the middle of two disks, we installed a slender stainless wire for generating hydrogen bubble. The electricity for the wire is supplied through a slipring. By using two CCD cameras, one is for top view and another is for side view, the device for composing the image from two CCD cameras and a video tape recorder,we could record the behavior of three dimensional bubble motions. After that by using the apparatus for image enhancement, we could trace the instantaneous three dimensional motion of bubbles.Finally, to check the effectiveness of this system, we simulated the motion of a single bubble generated just in the middle of two rotating disks. As a result, we recognized that this system is effective for observing the unstable flow from the rotating coordinate system quantitatively, but is not effective for observing the flow in the direction of the axis of rotation because of the buoyant force acting on the bubble. Less