S0501-1-6 減衰乱流と気泡群が誘起する流れ場の相互干渉によるエネルギースペクトルの変化([S0501-1 ]複雑流体の流動現象(1))

抄録

The objective is to clarify the turbulence modulation induced by interaction between a bubble swarm and oscillating-grid decaying turbulence. In order to generate simultaneously ideally homogeneous isotropic turbulence and a sufficiently controlled bubble swarm. First, the homogeneous isotropic turbulence was formed by operating oscillating-grid in cylindrical acrylic pipe (height: 600 mm, inner diameter: 149 mm) filled with ion-exchanged and degassed water. Second, we stopped the oscillating-grid in arbitrary time after the homogeneous isotropic turbulence was achieved. A few moments later, well-controlled bubble swarm was launched into the decaying turbulence by using bubble generators. The bubble formation, bubble size and bubble-launch timing are controlled arbitrarily and precisely by the bubble generators. We applied visualization of bubble motion to clarify the effect of liquid motion on bubble motion and PIV measurement to clarify the turbulence modulation. From the results, the bubble motion was changed from zigzag motion to 3-dimensional motion in the decaying turbulence and the standard deviations of liquid-phase velocity in case which the bubble swarm launched in the decaying turbulence was finally smaller than that in case of only decaying turbulence.