Experimental investigation of separation flow and perturbation in dden expansion pipe

• Main Authors: Lin,chi-chen, 林智全
• Other Authors: Wang,an-bang
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/96648012999671276695

碩士 === 國立臺灣大學 === 應用力學研究所 === 81 === The instability of the flow through axisymmetricn pipe caused by small thermal interference is experimentally studied low and high Reynolds number region in the project. The flow in region of low Reynolds number is qualitatively investigated by visualization, and the flow in the high Reynolds number is measured by LDA. An asymmetric flow structure caused by a small thermal difference the upstream and downstream of sudden- expansion pipe with only magnitude .minpl 0.15 .degree.C is found in the low speed flow time in the literature. The influential parameters for the flow the asymmetric flow include the temperature difference, the and the Reynolds number, and they are investigated in thisively. The asymmetric flow structure is very sensitive to theference between upstream and downstream of the sudden-expansion pipe, structure of asymmetric flow remains quite stable after the perturbation of pressure-wave from pipe downstream and the of momentum from the side-flow near the expansion. The separated flow becomes symmetric for the case of high Reynolds number. The reattachment length for Re=1000 .bksimlr. 100000 and the velocities in high Reynolds number (Re = 15200) is measured bynemometer. The results could be used as a data bank for the furtherand numerical modelling.