Drag Reduction by Different Solutions of Polymers in Gravity Driven Flow

Experiments are performed for assessing the extent of drag reduction using different water soluble polymer solutions for the case of a liquid drained from a large cylindrical tank through exit pipes. The diameters of exit pipes considered are 2.89X10⁻³m and 4X10⁻³m.The polymers used are polyacrylamide and polythene oxide. Experiments are performed using these polymer solutions for laminar as well as turbulent flow in the exit pipe. The optimum concentrations of polymer solutions which give maximum drag reduction are established. It has been observed that the optimum concentration is influenced by the type of polymer and the type of flow in the exit pipe. It has also been observed that polythene oxide is a better drag reducing agent when the flow in the exit pipe is laminar and polyacrylamide is a better drag reducing agent when the flow in the exit pipe line is turbulent.