Turbulator Effects on Heat Transfer and Flow Characteristics in Side-open End-sealed Duct Flows

• Main Authors: Zhe-Shaun Kuo, 郭哲翔
• Other Authors: Tzeng-Yuan Chen
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/84063540511230480181

碩士 === 淡江大學 === 航空太空工程學系碩士班 === 94 === The research experimentally investigate the turbulator effects on heat transfer and flow characteristics in a side-open, end-sealed duct, which simulates the cooling passages in the fin-type heat sinks of electronic equipments. Specifically, this research investigates the effects of fluid side-leakage and turbulator on the flow structures and near-wall flow characteristics, such as the convective mean velocity, the secondary flow and the turbulent kinetic energy. A wind tunnel system is used to generate a uniform flow at the inlet of the side-open, end-sealed duct. The Reynolds number is between 1500 and 15000. The turbulator have three type, such as a 45�� delta-wing turbulator, a 10�� delta-wing turbulator and a 90�� rectangular-wing turbulator. The turbulator is placed at the inlet of the duct for the turbulator-effect study. The measurements include three-component mean and fluctuating velocities at duct cross-sections and near the duct wall. Results of this study indicate that the flow in the central plane of the duct is similar to an impinging flow. Due to the reverse pressure by the end wall and the friction force by the duct wall, the flow reversal occurs near the duct wall. The reversal flow occurs earlier for smaller Reynolds number than that for larger Reynolds because of the smaller flow kinetic energy. The effects of the turbulator causes lager dead water flow region and, thus, results in worse convective effect. However, the turbulator causes the larger secondary velocity and turbulent kinetic energy and, thus, results in better secondary and turbulent effects on the near-wall flow characteristics.