Ph.D. Tezi Görüntüleme | |||||||||||||||||||||
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| Summary: The flows around square section bluff bodies, such as high-rise buildings, fan-coils, some parts of ships and submarines, aircrafts and road vehicles etc., are encountered in practical applications. In such designs, it is aimed that the control of drag and lift force, the enhancement of heat transfer and the thermal protection. The injection or suction through the perforated surfaces of the bodies is a known method of controlling the various flow and aerodynamic parameters. In the context of this thesis, the surface pressure distribution and the vortex shedding frequency were investigated for the flow around perforated horizontal and diagonal square cylinders with uniform injection through various surfaces. For this purpose, surface pressure measurements on each square cylinder (horizontal and diagonal) and vortex shedding frequency measurements in the wake region were performed at three different Reynolds numbers (10000, 16000, 24000) in a wind tunnel. The parameters considered were injection coefficient, position of perforated surface (i.e., top, rear, top-rear, all etc.), pressure coefficient, drag coefficient, lift coefficient and the Strouhal number. In addition, the drag and lift coefficients of the horizontal square cylinder were computed by a home made code which includes the uniform injection effects through surfaces with the proper boundary conditions. For this purpose, the k- turbulence model with Kato and Launder modification was employed and the differential equations were discretized by the finite control volume method.The results showed that the lowest drag coefficient of the horizontal square cylinder was obtained for the highest injection velocity through top-rear-bottom surfaces, while the highest value was obtained for the highest injection velocity through front surface. The lowest values of the Strouhal number were obtained for the injections through rear and all surfaces, which is the finest application for the vortex dynamics control. In case of the diagonal square cylinder, the lowest drag coefficient was obtained for the injection through front surfaces. The Strouhal number was increased with increasing injection velocity for the all configurations except the injection though front-top surfaces which the Strouhal number was constant. The numerical results showed a good agreement with the measurements of the injections through one and two surfaces, while some discrepancies were seen in other injection applications. Key Words: Perforated Square Cylinder, Injection, Pressure Coefficient, Drag and Lift Coefficients, Vortex Frequency
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