The Flow between Corotating Disks with an Obstruction in a Cylindrical Enclosure

• Main Authors: LiKuan Wong, 王立冠
• Other Authors: Chen Yau Ming
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/97710143097511205445

碩士 === 國立臺灣大學 === 機械工程學研究所 === 87 === The flow between corotating disks with an obstruction in a cylindrical enclosure is investigated experimentally in this study. The effect of rotating Reynolds number, obstruction geometry and penetration angle on the flow is discussed in detail. Laser Doppler Velocimeter together with the power spectra analysis method was used to measure the flow field. The result shows that the flow field can be classified into five regions, namely, inner region, vortex region, recirculation region, wake region and the region near the tip of the obstruction. From the results of velocity spectra, three kinds of flow pattern can be identified. These include: (a)Periodic flow type (b)Transitional flow type (c)Non-periodic flow type. With Increasing obstruction length and thickness, the flow pattern will vary from periodic flow to transitional flow, and finally become Non-periodic flow. It is found that in the transitional flow type the flow oscillate with abundant frequencies near the hub and the tip of obstruction, and there exists a critical obstruction blockage ratio which makes the power spectra intensity exhibiting a maximum near the tip of the obstruction. In addition, the effect of obstruction penetration angle on the flow shows good consistency with that of obstruction length projected at zero penetration angle. The flow between corotating disks is to be mainly influenced by obstruction geometry, and less sensitive to Reynolds number.