Vogel and Patterson 



log <p 



Additive 

 probe up 1.5cm 



No additive 

 probe up i.5cm 



^ ^Additive - probe centre-line ot woke 



Additive — .^^ 

 probe up 3cm. 



No additive z , 



probe up 3cm 



-ir 



W-No additive - probe centre-line of wake 



Tunnel velocity - 400 cm/sec 

 SOOppm. Polyox WSR-301 

 Flow rote - 30m I /sec. 



0.5 



log k 



1.5 



Fig. Zl - Turbulent velocity power spectra 



best reduction in friction was obtained by a linear, high molecular weight mole- 

 cule. The three POLYOX resins gave very good results in pipe-flow and rotating- 

 disc experiments (Fabula, 1963; Hoyt and Fabula 1964) and were chosen for this 

 work because of the amount of information available on some of their character- 

 istics. Limiting ourselves to POLYOX limits the number a variables of the poly- 

 mer characteristics to that of molecular weight. 



All the runs were carried out with the polymer solutions and the water in the 

 tunnel at a temperature of between 19.5° and 21° C so that if there are any tem- 

 perature effects on the drag reduction they would not show up in this work. The 

 use of standard mixing techniques should give solutions which if degraded, will 

 have a constant degradation for each concentration of each polymer used. It is 

 proposed in future to measure the molecular weights of the polymers after they 

 have been mixed so that any degradation can be determined. 



Increasing the molecular weight of the polymer gave increasing drag reduc- 

 tion as has been demonstrated by Fabula et al. It Is difficult to relate our results 

 directly to those of Hoyt and Fabula as we have an unknown but large dilution of 

 the polymer solution when it is injected into the boundary layer. Measurements 

 in the wake using a 100 ppm POLYOX WSR-301 solution indicate that a dilution 



994 



