Effects of inner cylinder rotation on laminar flow of a Newtonian fluid through an eccentric annulus

Abstract

The paper concerns a computational and experimental study of fully developed laminar flow of a Newtonian liquid through an eccentric annulus with combined bulk axial flow and inner cylinder rotation. The results are reported for calculations of the flowfield, wall shear stress distribution and friction factor for a range of values of eccentricity ε , radius ratio κ and Taylor number Ta . For fully developed flow the radial/tangential motion is decoupled from the axial component of velocity. However, the axial component of velocity is directly affected by the radial/tangential velocity field and rotation of the inner cylinder is found to have a strong influence on the axial velocity distribution, ultimately leading to two maxima in the case of a highly eccentred inner cylinder at high rotation speeds, a feature not reported hitherto. This influence of rotation on the axial velocity is mirrored in the behaviour of the shear stresses on the inner and outer cylinder walls and hence on the friction factor. An unexpected result is that (at fixed Reynolds number) as the Taylor number is increased the friction factor for high values of ε(>0.9) increases rather than decreases.