平面上の有限長角柱の渦流出および吹きおろしに及ぼす角の丸味の影響

概要

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This paper describes the effect of rounding side corners on vortices shedding and downwash from a square cylinder of finite length placed on a ground plane. The experiment was carried out in an N.P.L blowdown-type wind tunnel with a working section of 500 mm × 500 mm × 2000 mm in size at the Reynolds number 1.25 × 10^4 and 2.5 × 10^4. The power spectrum, autocorrelation and velocity were measured, and the Strouhal number was determined. The two types of vortices shed from a square cylinder with rounded side corners have also been observed. As a result, it was found that ( i ) the vortices shed from a cylinder are arch vortices for H/D = 2, which change into Karman vortices at H/D=4〜7 ; (ii) the decay of shedding vortices and turbulent eddies becomes fast and the average scale of turbulent eddies decreases as rounding of the side corners increases : (iii) the downwash from the free end weakens as rounding of the side corners increases.
一般社団法人日本機械学会の論文
1993-02-25