Fig. 1 Experimental apparatus.

Size: px

Start display at page:

Download "Fig. 1 Experimental apparatus."

そうりんなかじゅく
5 years ago
Views:

1 Effects of Concentration of Surfactant Solutions on Drag-Reducing Turbulent Boundary Layer In this study, the influence of a drag-reducing surfactant on the turbulent boundary layer was extensively investigated under different solution concentrations 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 concentrations tested were 100 and 150 ppm, and the previous data on surfactant solution of 65 ppm reduction ratio DR becomes larger downstream, and decreases with the increase of concentration from C=65 to 150 ppm. Regardless of solution concentrations, the value of the mean velocity scaled by the friction velocity increases with increasing the amount of drag reduction, while the mean velocity scaled by the free-stream velocity, which are collapsed for the different Reynolds number and drag reduction ratio, are about in the middle between the mean velocity profile of water and the Blasius laminar profile. For the present experimental conditions tested, the maximum of streamwise turbulence intensity near the wall is not related to the amount of DR directly and seems to be affected by the low Reynolds number effect strongly, while the location of the maximum becomes more distant from the wall with the increase of DR. The additional maximum of streamwise turbulence intensity near the center of the boundary layer, which is observed for all the concentration tested, and the wall-normal location of additional maximum are almost constant and are independent of the amount of drag reduction. Key Words : Non-Newtonian Fluid, Turbulent Flow, Boundary Layer, LDV, Velocity Distribution, Surfactant Solution, Drag Reduction

2 Fig. 1 Experimental apparatus.

4 Fig. 3 Effect of solution concentration on streamwise evolution of the boundary layer: (a) friction coefficient, (b) shape factor. Fig. 4 Effect of solution concentration on mean velocity: (a) 100 ppm, (b) 150 ppm.

5 Fig. 5 Effect of solution concentration on mean velocity in wall coordinates: (a) 100 ppm, (b) 150 ppm. Fig. 6 Effect of solution concentration on streamwise turbulence intensity: (a) 100 ppm, (b) 150 ppm.

7 Fig. 9 Effect of solution concentration on wallnormal turbulence intensity: (a) 100 ppm, (b) 150 ppm. Fig. 10 Effect of solution concentration on Reynolds shear stress: (a) 100 ppm, (b) 150 ppm.

8 (1) Virk, P.S., AIChE J., 21 (4), (1975), (2) Gyr, A. and Bewersdorff, H.-W., Drag Reduction of Turbulent Flows by Additives, Kluwer, Dordrecht, the Netherlands (1995). (3) Bewersdorff, H. -W., 1990, Drag reduction in surfactant solutions, in Structure of Turbulence and Drag Reduction, edited by A. Gyr (Springer, Berlin) pp (4) Chara, Z., Zakin, J.L., Severa, M. and Myska, J., Exp. Fluids, 16, (1993), (5) Hetsroni, G., Zakin, J.L. and Mosyak, A., Phys. Fluids, 9 (8), (1997), (6) Itoh, M., Imao, S., and Sugiyama, K., JSME Int. J., Ser. B, 40, (1997), (7) Warholic, M.D., Schmidt, G.M. and Hanratty, T.J., J. Fluid Mech., 388, (1999), (8) Kawaguchi, Y., Segawa, T., Feng, Z. and Li, P., Int. J. Heat Fluid Flow, 23, (2002), (9) Nowak, M., Exp. Fluids, 34, (2003), (10) Yu, B., Li, F., and Kawaguchi, Y., Int. J. Heat Fluid Flow, 25, (2004), (11) Li, F.-C., Kawaguchi, Y., Segawa, T., and Hishida, K., Phys. Fluids, 17, No , (2005). (12) Li, F.-C., Kawaguchi, Y., Hishida, K., and Oshima, M., Exp. Fluids, 40, (2006), (13) Itoh, M., Tamano, S., Yokota, K., and Ninagawa, M., Phys. Fluids, 17, No , (2005). (14) White, C. M., Somandepalli, V. S. R., and Mungal, M. G., Exp. Fluids, 36, (2004), (15) Hou, Y., Somandepalli, V. S. R., and Mungal, M. G., Exp. Fluids, 40, (2006), (16) Dimitropoulos, C. D., Dubief, Y., Shaqfeh, E. S. G., Moin, P., and Lele, S. K., Phys. Fluids, 17, No , (2005). (17) Dimitropoulos, C. D., Dubief, Y., Shaqfeh, E. S. G., and Moin, P., J. Fluid Mech., 566, (2006), (18) Tamano, S., Itoh, M., Hoshizaki, K., and Yokota, K., Phys. Fluids, 19, (2007), No (19) Coles, D.E., Rand Rep., R-403-PR, (1962). (20) Schlichting, H., Boundary-Layer Theory 7th edn, McGraw-Hill, (1979).

teionkogaku43_527

teionkogaku43_527 特集 : 振動流によるエネルギー変換熱輸送現象と応用技術 * Oscillatory Flow in a Thermoacoustic Sound-wave Generator - Flow around the Resonance Tube Outlet - Masayasu HATAZAWA * Synopsis: This research describes the oscillatory