THE EFFECT OF EJECTED POLYMER SOLUTIONS ON THE RESISTANCE AND WAKE OF A FLAT PLATE IN A WATER FLOW.
HYDRONAUTICS INC LAUREL MD
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An experimental investigation was made into the effects of injecting non-Newtonian fluids into the turbulent boundary layer of a flat plate. The ejection of weakly viscoelastic solutions of a macromolecular polymer at the leading edge of the plate decreased its drag coefficient by as much as 50 the Reynolds number of the plate was 1.8 x 10 to the 6th power. It was found that for a given ejection rate and free stream velocity there was a solution concentration for which the drag coefficient was a minimum. It is conjectured that the relatively sharp loss of effectiveness for higher concentrations may be due to insufficient mixing of the additive into the turbulent boundary layer. Ejection of neutrally buoyant spherical particles, not too much larger than the macromolecules, had no effect on the drag of the plate, indicating that the drag reduction is probably associated with the viscoelastic properties of the solutions studied. Author