Accession Number : AD0683230

Title :   TURBULENCE SUPPRESSION AND VISCOUS DRAG REDUCTION BY NON-NEWTONIAN ADDITIVES,

Corporate Author : WATERLOO UNIV (ONTARIO) DEPT OF MECHANICAL ENGINEERING

Personal Author(s) : Kowalski,T.

Report Date : 1967

Pagination or Media Count : 11

Abstract : Experiments are described which indicate that a practical use of the so-called non-Newtonian additives may be possible in reducing the viscous drag in full size ships. Until now the huge amounts of additives thought to be required for continuous injection into the boundary layer of water-borne craft precluded the possibility of full scale application except in cases of injections of very short duration. Results of present tests show that additives of the long-chain linear polymer type exhibit a persistence effect and a concentration effect in the boundary layer. It was determined, on the basis of turbulent velocity measurements by means of a hot film sensor, that the effect of polymer injection persisted for some time after the injection was stopped. Pulsing of injection was then developed which produced results similar to continuous injection at an approximate tenfold saving of the additive. From visual observations of injection of polymer and water it became clear that injected polymer concentrated closer to the boundary than similarly injected water. This suggested a possible surface seeking effect of the polymer which produced variation in concentration of additive in the boundary layer and also the above mentioned persistence effect. All the tests indicated that the effect of polymer was greatest when it was concentrated close to the solid boundary. This was confirmed by tests using a number of injection slots from 90 deg to 5 deg inclination to the direction of flow. The 5 deg slot produced an almost tangential injection jet of polymer and was used throughout the experiment. (AUTHOR)

Descriptors :   (*SHIPS, DRAG), (*DRAG, REDUCTION), ADDITIVES, BOUNDARY LAYER, INJECTION, SKIN FRICTION, TURBULENCE, POLYMERS, CANADA

Subject Categories : Marine Engineering
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE