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ISSN Druckformat: 2152-5102
ISSN Online: 2152-5110
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Effect of Polymer on Drag Reduction in a Sudden Enlargement of Pipe Cross Section
ABSTRAKT
The purpose of the present paper is to study experimentally the effect of drag reducing polymers on loasses due to friction and sudden enlargement of pipe cross section. Polymers used in this research include copolymer of acrylamaide with a cationic acid (ACA) and sodium carboxymethyl cellulose (CMC). Two different geometeries were considered, a sudden enlargement in pipe diameter from 27 to 40.5 mm diameter ratio (DR) of 1 : 1.75, and (b) from 27 to 54 mm (DR =1 : 2). The effect of Reynolds number change, polymer type, polymer concentration, and area ratio were studied. The upstream Reynolds number was varied from 5 · 104 to 105 and polymer concentration from 3 to 32 ppm inside the test section. The experimental results showed that the percent drag reduction increases with increasing both Reynolds number and polymer concentration. Drag reduction up to 63.47 % was obtained at 5 · 104 Reynolds with 32 ppm of ACA in upstream side and drag reduction reappears in downstream side when it was large in the upstream side. While CMC was not effective when used as a drag reducing agent in this range of concentration. Moreover, the sudden enlargement factor was decreased by 18 % when using 32 ppm of ACA at 5 · 104 Reynolds number. Also, using ACA as a drag reducing agent enhances pressure distribution in the upstream and downstream pipe flow.
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