Dynamics of Secondary Steady State Flows in a Combined Taylor-Couette and Escudier Vortex Breakdown Flow Field

Abstract

Effects of a varying height end-wall on the bifurcation and stability of secondary steady state flows within the annular gap of a Taylor-Couette cell were investigated. Experiments were conducted at four different end-wall aspect ratios of Γew = 0, 0.5, 1.0, and 1.5 at Taylor numbers between Ta = 1,312 - 35,485. Co-rotation, counter-rotation, and stationary endwall rotational conditions were investigated for the three larger aspect ratios, at end-wall Reynolds numbers between Reew = 944 - 2,926. Increases in Γew were found to attenuate both the structural stability and vorticity of annular Taylor vortices. Co-rotation was found to dampen the effects of increases in Γew while counter-rotation was found to enhance the effects of increases in Γew. The changes in vortex stability and vorticity were found to result primarily from oscillatory axial flow within the annulus. This axial flow was found to be greatest at Γew = 1.0, and 1.5 where a flow similar to the vortex breakdown bubble found by Escudier [24] was found to occur in the zone-2 region between the inner cylinder and upper end-wall. The presence of these zone-2 vortical structures was found to play a pivotal role in Taylor vortex stability and subsequent distortions at higher Ta numbers.