Drag Coefficient for Tethered Spheres In a Vertical Pipeline With and Without Polymer Addition

Abstract

<p>This thesis is concerned with experimental study of the drag coefficient of tethered spheres in a vertical pipeline of approximately 0.05 m diameter using water and dilute polymer solutions.</p> <p>Experiments were conducted using four different sphere-to-tube diameter ratios ranging from 0.439 to 0.87. The liquid velocities as well as the associated drag forces and pressure drops were measured, which enabled both the drag coefficients and pressure functions to be computed.</p> <p>Semi-empirical correlations were obtained for the drag coefficient and the pressure function in the range of tube Reynolds number of 3.9 x 10³ to 9.2 x 10⁴.</p> <p>In the experiments using Reten 423 for the diluted polymer solutions, it was observed that a maximized drag reduction would occur at concentration of about 24 wppm for spheres of d/D > 0.74. Drag reductions of up to 60% were obtained which are of a higher order of magnitude than that for non-tethered spheres which has been previously observed.</p>