CHARACTERISTICS OF FLUID FLOW BETWEEN SINGLE RIGID BODY AND WALL OF SMALL-DIAMETER TUBE

摘要

A multibody system that moves with fluid inside a small-diameter tube is applied to some parts of industry such as a PIG and it is also expected to be developed for future engineering applications. As a first step to considering a multibody system, this study focused on elucidating the flow characteristics around a single rigid body and understanding the effect of a bypass hole. The model considered has been a single rigid body moving at a constant velocity in a narrow tube. Assuming that the flow is steady axisymmetric laminar flow, the fluid flow around the body has been experimentally observed and numerically analyzed. A Rankine's combined vortex was observed around the body and it was also observed that a layer of fluid near the top wall has characteristics of the boundary layer. Furthermore, a minimum allowable thickness of a bypass hole to cause the successful front-drive effect was obtained.