Flow Between Co-rotating Disks in a Cylindrical Enclosure

• Main Authors: Lin Shi Zheng, 林士正
• Other Authors: 陳瑤明
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/17613229024554892596

碩士 === 國立臺灣大學 === 機械工程學研究所 === 87 === In this study, experiments are performed to investigate the flow past an obstruction located between co-rotating disks in a cylindrical enclosure. Laser Doppler velocimeter was applied to measure the time-history of velocity in the mid-plane between the two disks. Fast Fourier transformation was then used in the spectrum analysis. For comparison, flow without obstructions was also measured. For the cases without obstructions, six interdisk spacings (H) are considered. The aspect ratio is varied from S = 0.06 to 0.22 (with S = H/R2), where R2 is the disk radius. The experimental results show that a larger spacing between disks alters the disappearance of the solid-rotation region. When obstructed flow was investigated, four different length (L), four different thickness (T) of the obstructions and two various values of Reynolds number (Re = 5.2  105 and 1.04  106) were considered respectively. The non-dimensional length of obstruction is changed from L* = 0.3 to 0.8 (with L* = L / (R2+a-R1)), the non-dimensional thickness is changed from T* = 0.17 to 0.62 (with T* = T / R2). Finally, the cross-sectional shape of obstruction was taken into account, they are rectangle, circle, sector and gibbous rectangle. According to the experimental results, a thicker and longer obstruction will turn the flow pattern from periodic flow to non-periodic one. An obstruction with more streamline-like cross-section will alter the flow characteristics by moving toward higher frequency.