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Rotating disk apparatus for polymer-induced turbulent drag reduction
Cheng Hai Hong,최형진,김재호 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.10
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.
Turbulent Drag Reduction and Mechanical Degradation of Polyisobutylene in Kerosene
Lim, Sung Taek,Lee, Kiho,Kim, Chul Am,Choi, Hyoung Jin,Kim, Jae Guen,Jhon, Myung S. 한국공업화학회 2002 Journal of Industrial and Engineering Chemistry Vol.8 No.4
We investigated turbulent drag reduction induced by polyisobutylene molecules dissolved in kerosene and their chain degradation under a turbulent flow. Using a rotating disk apparatus, we found that drag reduction efficiency decreased with time due to mechanical degradation of the polyisobutylene molecules. The theoretical equation for molecular degradation based on midpoint scission in a turbulent flow was found to be well fitted to high concentration polymer solutions in a mildly turbulent flow.