The Combined Effect of Rib with Single Large Eddy Break Up Devices on Flow and Heat Transfer Characteristic of Turbulent Flow in Rectangular Duct

• Main Authors: Ekhlas Mohammed Fayyedh, Moayed R. Hasan, Ali Falah Mohammed
• Format: Article
• Language: English
• Published: Al-Nahrain Journal for Engineering Sciences 2017-01-01
• Series: مجلة النهرين للعلوم الهندسية
• Subjects: Drag reduction; turbulence manipulation; large-eddy break-up devices
• Online Access: https://nahje.com/index.php/main/article/view/102
• ISSN: 2521-9154; 2521-9162

An experimental investigation has been performed to study the effect of combined  artificially roughened (ribs) with and without  single Large Eddy Break-Up Devices, on flow and heat transfer  characteristic of fully developed turbulent flow in rectangular duct. The aspect ratio of rectangular duct is 10, hydraulic diameter  72.72 mm, relative roughness pitch (P/e) 10 and relative roughness height (e/Dh)  0.05. The rib was in the form of circular shape with diameter of (4mm) which was mounted on heated wall of duct at spanwise direction. The experiments have been  conducted by varying airflow rate in terms of Reynolds number ranging from 3.2x104 to 6.2x104 and constant heat flux of 600W/m2. The heat transfer and friction factor of the flow for rib and combined method were compared with those of a smooth duct under similar experimental conditions. It has been found that the combined method (rib with single Large Eddy Break-Up Devices) has significant effect on the friction factor and heat transfer with decreasing in friction factor with percent(1.2) and increasing Nusselt number with (4.1).  Correlations for Nusselt number and friction factor in terms of (Reynolds number and Large Eddy Break-Up Devices) parameters are found which reasonably correlate the experimental data.