Cheng Hai Hong
The Journal of Mechanical Science and Technology, vol. 22, no. 10, pp.1908-1913, 2008

Abstract : In order to investigate turbulent drag reduction (DR), a rotating disk apparatus (RDA) generating an “external flow” was designed and then polymer-induced DR efficiency of water-soluble polymers both poly (ethylene oxide) (PEO) and poly (acryl amide) (PAAM) were examined as a function of either polymer concentration or temperature. The need for a sensitive measuring system at high Reynolds numbers has stimulated the development of a high-precision computer- aided system, which is able to measure the difference between the torques for a Newtonian fluid and a dilute polymeric solution with drag reducers very accurately. Their mechanical degradation behavior in the RDA as a function of time in a turbulent flow was also analyzed using both a simple exponential decay function and a fractional exponential decay equation. The fractional exponential decay equation was found to fit the experimental data better than the simple first-order degradation exponential decay function in the case of PEO.

Keyword : Drag reduction; Rotating disk apparatus; PEO; PAAM