Vogel and Patterson 



1. The drag of the body was decreased as the molecular weight of the poly- 

 mer was Increased. At tunnel velocities of 300 cm/sec and 400 cm/sec the re- 

 sults for the two lower molecular weight polymers, POLYOX WSR-35 and -205, 

 were almost the same. At 500 cm/sec and 600 cm/sec the differences were 

 greater. POLYOX WSR-301 was at least twice as effective as WSR-205 at all 

 tunnel speeds used. 



2. The drag of the body was decreased as the concentration of the polymer 

 solution was increased. However, for POLYOX WSR-301, the amount of drag re- 

 duction decreased at concentrations above 500 ppm. No runs were carried out 

 with concentrations greater than 250 ppm for the other two polymers. 



3. For increased polymer flow rates, the drag reduction increased. There 

 was some indication that a plateau in the drag reduction was reached at flow 

 rates greater than 50 ml/sec. Whether this is a limitation of the experimental 

 equipment or a real effect in the boundary layer was not determined. 



4. The flow rate of the polymer solution injected into the boundary layer, 

 and not the injection flow velocity, was the controlling factor at the injection 

 velocities and polymer concentrations used. 



5. Dye-injection studies indicated that for a concentration of 100 ppm of 

 POLYOX WSR-301 the fluid was quickly mixed through the boundary layer. The 

 dilution of the injected fluid appeared to be at least 100:1 and was found to be 

 10,000:1 at the edge of the wake 7 cm downstream of the body. 



6. Turbulence and mean velocity measurements were made in the wake 7 

 cm downstream of the body. These preliminary measurements showed that: 



(a) For the 100 ppm solution of POLYOX WSR-301, the average velocity 

 increased and the mean square of the turbulence decreased when the polymer was 

 injected. Both these effects were distributed across the full width of the wake. 

 Previous runs with dye had indicated that the polymer solution was distributed 

 through the whole wake. The power spectra of the turbulence signal measured 

 0.5 cm above the centre-line of the wake, indicated that the decrease in turbu- 

 lence energy occured over the wave number range measured. 



(b) For the 500 ppm solution of POLYOX WSR-301, the average velocity 

 was markedly increased over the central portion of the wake, but was not 

 changed very much in the outer portion of the wake. The turbulence level in- 

 creased over the central portion of the wake but was not changed very much in 

 the outer portion of the wake. No dye measurements were carried out to deter- 

 mine if the polymer solution was concentrated in the central portion. The 

 power spectra of the turbulence signals indicated that for the small wave num- 

 bers the curves for the polymer flow were higher than the curves for no addi- 

 tive. At the centre-line of the wake, the curves crossed, indicating that at the 

 higher wave numbers the energy in the turbulence was reduced when the polymer 

 solution was injected. With the probe 3 cm above the wake centre-line, the addi- 

 tive curve was again higher, but the curves appeared to cross at the limit of the 

 wave number range analyzed. 



996 



