FLOW PATTERNS IN A COMBINED TAYLOR-COUETTE GEOMETRY

The Taylor Couette problem, which is the fluid motion in an annulus between two concentric rotating bodies, is a convenient flow system to study the laminar-turbulent transition and has a fundamental interest in the wavenumber selection processes. This paper presents a numerical study of conical Taylor-Couette flows when the inner cylinder is a regular straight cylinder, but the outer cylinder has a tilted, conical shape. The apex angle between the inner cylinder and the outer cone is varied between 0 and 12 degrees. The parameter that determines the flow regimes is the Taylor number based on the angular velocity of the inner cylinder. The calculations are carried out using a three-dimensional CFD of incompressible viscous flow. Computations for the onset of Taylor vortices in the classical configuration with straight cylinders show good agreement with experimental data. For the case of a conical outer cylinder, calculations show a decrease in the critical Taylor number for the onset of the first instability along with the number of rolls with the apex angle. The main result of this geometrical modification is that the gap width varies in height, and the Taylor vortices then vary in size, being large where the gap is wide, and small where the gap is narrow. Pressure distribution is also computed.