正浮力後流の三次元熱流動解析 : 第3報,三次元構造に与える正浮力の影響(熱工学,内燃機関,動力など)

概要

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The wake with positive buoyancy at the Reynolds number 300 and the Richardson number 0.3 of air was analyzed by the DNS computation, and revealed as follows: Positive buoyancy effects are that one is Effect I, that is, a decrease of the axial direction vorticity |ω_z|, and the other is Effect II, that is, a decrease of the 3D motion, i. e. the vorticities |ω_x|, |ω_y| with the upward and horizontal directions, and the velocity |ω| with the axial direction. Effect II is more dominant than Effect I. That is, the 3D motion moving right and left decreases remarkably, but the suppression of vortex street becomes weak. A space effect of Effect II is that the vortex dislocation becomes vague and a dislocation location becomes time-dependent. A time effect of Effect II is that the frequency of the 3D motion increases, the amplitude of the motion decreases, and the formation region length decreases. A space and time effect of Effect II is that the oscillation mode becomes the B mode with 1 of the wave length Λ, and 2f_<wake> and 5f_<wake> of the dominant frequency f_p of the 3D motion in the nearwake, and the A* mode with 3 of Λ, 2f_<wake> of f_p, and the weak vortex-dislocation in the farwake, here f_<wake> is the wake frequency.
一般社団法人日本機械学会の論文
2004-05-25