The pipeline flow of capsules part 4 ‐ an experimental investigation of the transport in water of single cylindrical “capsules” with density greater than that of the water

Abstract

AbstractThe last paper in this capsule pipelining series described investigations of the flow of equal‐density capsules transported by water in a horizontal pipe. In the present study, attention was directed to the flow of capsules with specific gravities in the range of 1.19 to 8.30. As before, capsules were used with diameter ratios of 0.39 to 0.89, and length to diameter ratios of 2 to 14, both flat and ellipsoidal end shapes being included.With water velocities greater than about 3 ft./sec., the larger diameter capsules moved at velocities up to 15% greater than the average water velocity, the actual values depending mainly on the capsule diameter and density. The velocity ratio, capsule velocity/‐average water velocity, typically increased with either increase of diameter or decrease of density, other factors being constant.Longer capsules moved more slowly than shorter ones of the same diameter and density at low water velocities, but the velocity ratio of the longer capsules increased more rapidly than that of the shorter capsules at higher water velocities. An ellipsoidal nose materially increased the velocity of smaller diameter capsules but the effect on the largest diameter capsules was small.The reduction of the effects of density and surface roughness at the higher capsule velocities suggests the formation of a thickening film of water under the capsule as its velocity increases.