Drag reduction heterogeneous

Goren found asymptotic behaviour, which is higher for this heterogeneous drag reduction than for a premixed homogeneous solution, whereas Tullis, Ramu, and Maus reported only little influence of the concentration of the injected polymer solution on this asymptotic value. Walters and McComb (1982) found no such influence. 

Frings B (1988) Heterogeneous drag reduction in turbulent pipe flows using various injection techniques Rheol Acta 27 92... 

Usui H, Kodama M, Sano Y (1987) Drag reduction with heterogeneous polymer injection into a turbulent pipe flow Technol Rep Yamaguchi Univ 4 51... 

Vleggaar J, Tels M (1973) Heat transfer in a heterogeneous drag reduction system Int J Heat and Mass Transfer 16 1629... 

Figure 11-47. Drag reduction eilectiveness for heterogeneous discharges (PJ, plasma jet HF, high-frequency discharge MW, microwave).

Bewersdorff, H.-W, Gyr, A., Hoyer, K., and Tsinober, A., An investigation of possible mechanisms of heterogeneous drag reduction in pipe and channel flows, Rheol. Acta, 32,140-149 (1993). 

Heterogeneous drag reduction in turbulent pipe flow. 

All these experimental results demonstrate that drag reduction can also be obtained for a heterogeneous polymer distribution. It may be concluded that the mechanism of this type of drag reduction is different from that of a dilute polymer solution. The aim of the present work is to obtain more information about the characteristic features of this type of drag reduction by central injection of concentrated polymer solutions into the centre of a turbulent pipe flow. 

The ultimate values of drag reduction are nearly identical with those of homogeneous polymer solutions. The results for c 0.2% are in agreement with those published by Me COMB [l7, 18]. From fig. 4 it may be concluded that for Cp = 0.2% the polymer distribution is homogeneous and for c = 0.25% it is remarkably heterogeneous. This can be recognized by the differ-... 

Figure 6 Friction behaviour for homogeneous and heterogeneous drag reduction.

VLEGGAAR, J., M. TELS, Heat transfer in heterogeneous drag reduction system, Int. J. Heat and Mass Transfer, J 6 (1973) 1629-1632. 

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