Wheeled Capsule Threshold of Motion at Different Locations in a Horizontal Bend Pipeline Based on Hydraulic Capsule Pipeline Transportation

Abstract

As the process before the transporting of the capsule in a hydraulic capsule pipeline system, the capsule’s threshold of motion process is often tested in the horizontal straight pipe. However, the result of the physical test in this work shows that the wheeled capsule more easily start-moves in a horizontal bent pipe. Thus, the numerical simulation and the theory analysis were used to study the wheeled capsule’s threshold of motion process in the bent pipe. The simulation results demonstrate that the velocity magnitude of the water flow was asymmetric between the inner part and the outer part of the section closing on the wheeled capsule. This was unlike the water flow of the section in the straight pipe. From this result, a new mechanical model was proposed that divides the wheeled capsule into two parts. The two parts of the mechanical model correspond to the two parts of the section. Then, the deduction has shown that the bolsters of the inner part of the wheeled capsule in the bent pipe endured lower maximum static friction than those in the straight pipe. The whole wheeled capsule was more unstable in the bent pipe than in the straight pipe because of the additional drag force induced by the centrifugal effect of the bent pipe’s water flow.

Modal Analysis of the Hydrodynamic Force of a Capsule in a Hydraulic Capsule Pipeline

“…The hydrodynamic forces acting on capsules have been divided into frictional drag and pressurized drag [28]. Frictional drag has been calculated by using the Laminar approximation of annular gap flow and revising the calculation through experimental results, expressing the frictional drag as an integral of the shearing stresses around the capsule [29]. Pressurized drag has been modeled using physical experiments to determine the integral of the normal stresses around the capsule.…”