Additives Injected Into the Boundary Layer of an Underwater Body 



10 

 Drog 

 Reduction- gms 



8 



lOOppm. Polyox WSR-301 

 Tunnel velocity 425cm/sec 



Nose Slot width - O 0.25 mm. 

 + 0.5mm. 

 A 0.9mm. 



) 10 20 30 40 ! 



Polymer injection flow rote - ml/sec. 



Fig. 15 - Drag reduction vs polymer injection flow rate 



20- 



Drag 

 Reduction -gms 



— I 1 1 r 



100 ppm. Polyox WSR- 30! 

 0.25mm. Nose Slot 

 Flow Rote 30ml/sec. 



Sfondord 

 solution 



Degroded 

 solution 



100 200 300 400 500 



Tunnel velocity - cm/sec. 



600 



Fig. 16 - Effect of polymer degradation 

 on drag reduction 



Figure 17 shows the results of these runs. It is apparent from the dye con- 

 centration contours that the centre of the wake is between 1 cm and 1.5 cm 

 above the centre-line of the body. This means that the body had become mis- 

 aligned with the flow by about 1.75° for these runs. For the most part the dis- 

 tribution of the dye is very much the same for both the water and the polymer. 



989 



