Pipe Wall Effects On Suspension Velocities of Single Freely-Suspended Spheres and on Terminal Velocities of Single Spheres in a Pipe

This paper presents the following two velocities in terms of nondimensional factors : (a) The mean suspension velocities of single freely-suspended spheres in a pipe v1, (b) The terminal velocities of single spheres falling through still water in a pipe v2 . The experiments were carried out with changes in sphere diameter d, specific gravity of sphere γs, pipe diameter D and inclination angle of pipe Θ. The results obtained are summarized as follows : (1) v1 is not always identical with v2, (2) v1/vt = 1.024 - 1.329In(d/D + 1.0), (1) (3) v2/vt = 1.0 - 2.130(d/D)2.462 (2) for the spheres falling straighly along the pipe axis, or v2 /vt = 0.817 - 2.390(d/D)2.462 (3) for the spheres falling with oscillation in the pipe, where vt is the terminal velocity of single spheres in unbounded fluid, , (4) v2/v1 = 1.10 - 1.35, in the case of Eq . (2) and v2/v1 = 0.90 - 1.03, in the case of Eq . (3) .