細長い長方形断面柱のストローハル数と背圧係数

概要

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Strouhal number and base pressure coefficient of a cylinder with an elongated rectangular cross section of a width-to-height ratio (the B/H ratio) of 4 to 15 were measured in the range of Reynolds numbers between 200 and 7×10^3 in a wind tunnel, and flow around the cylinder was visualized by means of the electrolytic-precipitation method in a water tank. It was found that there exist two components with different Strouhal numbers in a flow field around the elongated cylinder with the B/H ratio of 5.5 to 6.5 in the limited range of Reynolds numbers of 600 to 2×10^3. It is clarified by experiments on a model whose nose is shaped like an aerofoil that the component with a high Strouhal frequency is induced by the vortices shed from trailing edges. The low Strouhal component is due to the oscillation of flow over the side walls accompanied by the movements of separation bubbles, so its value of Strouhal number, which is based on the streamwise length of the cylinder, remains constant; however, with further increase in the B/H ratio, it increases in a stepwise manner to values that are equal to the integral multiples.
一般社団法人日本機械学会の論文
1990-03-25