AN EXPERIMENTAL INVESTIGATION 



OF THE EFFECT OF ADDITIVES 



INJECTED INTO THE BOUNDARY 



LAYER OF AN UNDERWATER BODY 



W. M. Vogel and A. M. Patterson 



Pacific Naval Laboratory 

 Victoria, British Columbia, Canada 



ABSTRACT 



The effects of injecting solutions of three linear, high molecular weight 

 polymers into the boundary layer of a three-dimensional streamlined 

 model are being investigated. The following are the preliminary results 

 of this experiment: 



(a) The drag of the body decreased with increasing molecular weight of 

 the polymer. 



(b) The drag decreased as the concentration of the polymer solutions 

 increased. At concentrations above 500 ppm for the highest molec\alar 

 weight polymer used, the amount of drag reduction decreased. 



(c) For increased flow rates of the polymer solution, the drag reduc- 

 tion increased. 



(d) The flow rate of the solution injected into the boundary layer, and 

 not the injection flow velocity, was the controlling factor at the injec- 

 tion velocities used. 



(e) Turbulence and average velocity measurements in the wake of the 

 body indicated two effects when the polymer solution is injected: a 

 change in the mean square of the turbulence velocities, and a change in 

 the velocity profile. 



INTRODUCTION 



B. A. Toms (1949) pointed out that, in turbulent pipe flow, dilute solutions of 

 linear polymers reduced the pressure drop along the pipe to a value below that 

 of the solvent. Since then there has been a growing body of literature on the flow 

 of polymer solutions which exhibit non-Newtonian characteristics. Experimen- 

 tally, most of the studies have been concerned with the rheological characteris- 

 tics of the fluid, or with pipe friction. The work by Shaver (1957) showed that in 



975 



