Single Jet Impingement Cooling in a Stationary and Rotating Square Duct

• Main Authors: Jung-Tai Huang, 黃榮泰
• Other Authors: Shou-Shing Hsieh
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/99874953445579808196

博士 === 國立中山大學 === 機械與機電工程學系研究所 === 91 === Abstract The influence of rotating and cross flow effect on local heat transfer coefficient and flow visualization for a single confined air/water jet with jet-to-wall spacing from 5 to 11.4, jet Reynolds number from 6500 to 26000, rotational Reynolds number from 0 to 112000, curvature ratio from 150 to , ratio of crossflow massflux to jet mass flux from 0 to 2, and the heat flux from 1430 to 12890W/m2 were reported. The local heat transfer coefficient for air/water along the surface is measured and the effect of the rotation, the jet-to-wall spacing, the surface curvature, local and average Nusselt number, are presented and discussed. Furthermore, flow visualization was made in the present study. Based on the experimental result, it is found that the rotation will induce the centrifugal and coriolis force. It also shows that the heat transfer response will be decreased when the impinging direction parallel to the rotating direction, and increased when impinging direction perpendicular to the rotating direction. Crossflow effect will make Nusselt number decrease to 48% when M=2. Moreover, the roughen surface will increase the heat transfer coefficient up to 22% due to the secondary flow. The flow visualization is used to observe the transition of laminar to turbulence flow and to calculate the boundary layer thickness.