Vogel and Patterson 



10 

 Drag 

 Reduction - gms 



0:25 mm. Nose Slot 

 Flow Rote - 30 ml/sec 



•250 ppm. 



- 100 ppm. 



- 50 ppm. 



- 25 ppm. 



- 15 ppm. 



100 200 300 400 500 600 700 



Tunnel velocity - cm/sec. 



Fig. 6 - Drag reduction using POLYOX WSR-205 



not separated the body and wing drag, and as the drag reduction takes place es- 

 sentially over the body it was felt that plotting in terms of the actually drag re- 

 duction would give a clearer picture of the effect of additive injection. The in- 

 crease in the effectiveness of the polymer as the concentration is increased is 

 clearly shown. Figures 7 and 12 also show that a peak in the drag reduction 

 curve is reached somewhere between a concentration of 500 ppm and 1,000 ppm. 

 A similar peak occurred in the rotating-disc work carried out by Hoyt and 

 Fabula (1964). Complete agreement is not likely as there is a large unknown 

 dilution of the additive in our case. The increased drag reduction as the molec- 

 ular weight is increased is shown in Figs. 9 to 10. 



Figure 13 shows two sets of runs at a lower polymer flow rate of 13 ml/sec 

 (average velocity through the slot would be 87 cm/sec). These curves also show 

 that there is a decrease in the effectiveness of the polymer solution as the con- 

 centration is increased above about 500 ppm. Runs were also done injecting 

 water of flow rates of 30 ml/sec and greater; no drag reduction was observed 

 over the tunnel velocity range of 150-625 cm/sec. 



VELOCITY OF INJECTION OF THE SOLUTION 



Figure 14 shows the effect of increasing the flow rate of the polymer through 

 the nose slot. Although this effect is plotted for only 500 ppm of WSR-301 it was 

 also observed for other concentrations of the three polymers. Runs at other 



982 



