Resistance of Flow through an Annulus with an Inner Rotating Cylinder

Abstract

In this paper, the resistance of water flow throush co-axial cylinders is studied experimentally, when the inner cylinder rotates. The resistances are measured for six gap sizes (s/r1=0.0136∼0.115, s : gap, r1 : radius of inner cylinder) and for various combination of axial and rotational flows. Results obtained are as follows : 1. When the axial flow is laminar, the resistance of flow is unaffected up to a cartain rotating speed (Rωe : critical rotatins Reynolds number), but beyond this speed the flow resistance increases as the Rω increases. 2. The value of critical Taylor number Rωe(s/r1)1/2 increases as the axial Reynolds number(Re=vm s/ν) increases up to a certain value (Re=600), beyond this value Rωe (s/r1)1/2 decreasee to zero with the increase of Re. When the axial flow is turbulent, such a critical rotating Reynolds number Rωe cannot be recognized. 3. When Rω>10 000, resistance coefficient of flow λ can be expressed by [numerical formula]even for small Re.