界面活性剤水溶液の抵抗低減乱流境界層に及ぼす溶液温度の影響(流体工学,流体機械)

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In this study, the influence of a drag-reducing surfactant on the turbulent boundary layer was extensively investigated under different solution temperatures using a two-component laser-Doppler velocimetry system. The surfactant-solution used here was a mixture of cetyltrimethyl ammonium chloride (CTAC) with sodium salicylate as counterion, which was dissolved in tap water. The temperature of surfactant solution was T=20, 25, 30, and 35℃. It is found that the drag reduction ratio DR for C=65 and 100 ppm becomes smaller with the increase of the temperature from T=25 to 35℃, and the DR at T=20℃ is smaller than DR at T=25℃. We introduced three distinct regimes of drag reduction, which were referred to as low drag reduction (LDR), high drag reduction (HDR), and maximum drag reduction (MDR) regimes. The distributions of the mean velocity, the wall-normal turbulence intensity, and the Reynolds shear stress could be clarified by these three regimes, while the streamwise turbulence intensity profile could not be explained.
2008-05-25