Drag Reduction in Turbulent Flow Using Biopolymers

Abstract

The aim of this study is to investigate experimentally the effect of bio-polymers in the process of drag reduction in a single phase water flow at high Reynolds number. By using biopolymers, makes the entire process of polymer induced drag reduction economical and more versatile. A comparative study has been carried out using two high molecular weight bio-polymers guar gum D and hydroxyethyl cellulose (HEC). These two additives of different concentrations and flow rates, taken as parameters of study to observe the influence in drag reduction. Different concentrations of 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm and 3000 ppm are used at high Reynolds numbers to find the percentage of maximum drag reduction (%MDR) in the turbulent flow inside the pipe. In this experimental study shear viscosity of each concentration is measured by Brookfield viscometer, and validated with power law. From this study, it is found that there is significant decrease in skin friction drag with increase in concentration of polymer solutions. The maximum percentage of drag reduction is about 77.5% (HEC) as compared to 75% (GG) at high Reynolds number of 44309, with 3000 ppm concentration. The results found, are further validated with the universally accepted maximum drag reduction (MDR) asymptote or Virk’s asymptote. The mechanical degradation of the polymers due to the centrifugal pump is also studied and found that hydroxyethyl cellulose (HEC) has better self-life stability than the guar gum (GG). The test section consists of horizontal pipe of 19 mm inner diameter and 1524 mm long. The master solution is prepared by paddle stirrer with the range of 1600-2500 rpm. Injection of master solution in the test section is done by peristaltic pump at a rate of 450cc/hr., and the pressure difference across the pipe in the test section is measured by U-tube manometer. The pH of each concentration of the polymer solutions is also measured. The pH of guar gum lies within the range of 4-7 and that for hydroxyethyl cellulose lies between 7 to 8.2.