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Flow and Heat Transfer Characteristics due to the Variations of the Angle of Attack at the Vortex Generators located behind a Circular Cylinder  

하홍영 (대동공업(주) 기술연구소)
홍철현 (부산대학교 대학원 기계공학과)
양장식 (부산대학교 기계기술연구소)
이기백 (부산대학교 기계공학부 및 기계기술연구소)
Abstract
Experimental investigations of the flow structure and heat transfer enhancement in a channel with a built-in circular cylinder and a wing-let type vortex generator are presented. Without any vortex generators, relatively low heat transfer takes place in the downstream of the circular cylinder where is a recirculation region with low velocity fluid is formed. However with a wing-let type longitudinal vortex generator in the wake region behind the cylinder, heat transfer in the region can be enhanced. In order to control the strength of longitudinal vortices, the angle of attack of the vortex generators is varied from $20^{circ} to 45^{\circ}$, but spacings between the vortex generations are fixed to be 5 mm. The 3-dimensional mean velocity field downstream of the vortex generator is measured by a five-hole pressure probe, and the hue-capturing method using thermochromatic liquid crystals has been used to provide the local distribution of the heat transfer coefficient. The vorticity field and streamwise velocity contour are obtained from the velocity field. Streamwise distributions of averaged Stanton number on the measurement planes show very similar trends for all the experimental cases($\beta=20^{circ}, 30^{circ} and 45^{\circ}$). Circulation strength and heat transfer coefficient have the maximum values when the angle of attack($\beta$) is $30^{\circ}$.
Keywords
Circular Cylinder; Vortex Generator; Half Delta Wing; Heat Transfer; Five-Hole Pressure Probe; Thermochromatic Liquid Crystal;
Citations & Related Records
Times Cited By KSCI : 4  (Citation Analysis)
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