Torque and Pressure Drop of the Flow between Rotating Co-Axial Cylinders in Low Reynolds Number

Abstract

Using spindle oils, the writer studied experimentally the torque resistance and the pressure drop of the flow in co-axial cylinders of which inner cylinder rotates. Comparing the torque coefficient Cf with the pressure drop coefficient λ, the writer clarified the behaviors of the shearing stresses in the region of the small values of axial Reynolds number Re and of peripheral Reynolds number Rω. When Re=0, the critical peripheral Reynolds number Rωe at which instability of laminer flow occurs agrees well with the theory given by G. I. Taylor. When the value of Rω is larger than Rωe for Re=0, the value of Cf approaches to the theoretical value of the laminar flow as the value of Re increases. When the value of Re increases still larger, however, transition to the turbulent flow occurs and the value of Cf increases again. When Rω is larger than the value above mentioned, the value of Cf does not approaches to that of laminar flow and variation of Cf becomes smaller and smaller as the value of Rω increases.