S0502-4-1 円柱の抗力低減に関する研究([S0502-4]噴流,後流および剥離流れ現象の解明と制御(4))

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In this study, the cylinder which set grooves in the surface was designed so that it might correspond to all the direction of the wind for the purpose of cylinder drag reduction, and characteristic tests were performed using the wind tunnel experimental device. The relationship between a Strouhal number and Reynolds number was investigated in the range of mainstream velocity 2.5 m/s to 35 m/s (the range corresponding to Reynolds number is 1×10^4 to 1.2×10^5). In order to check turbulent flow transition, comparison of the wake width of a smooth cylinder and two kinds of circular cylinder with grooves was performed by Reynolds number 4×10^4. As the results of experiments, it was found that the drag reduction effect changes in the depth of a groove. It was shown that the cylinder with the deep depth of a groove is not influenced by the direction of wind. The value of a drag coefficient was about 56% of a value of the drag coefficient of a smooth cylinder. It was shown that the wake width of the proposed cylinder narrows from the wake width of the smooth cylinder.
2010-09-04