Angular momentum transport and flow super-rotation in Rayleigh stable Taylor-Couette

We present experimental velocimetry and torque measurements for Taylor-Couette flow in the Rayleigh stable regime. Measurements are taken on two geometrically similar experiments, both of which had axial boundaries attatched to the outer cylinder, which is known to cause Ekman pumping. The Twente experiment has a radius ratio of 0.716, an aspect ratio of 11.68, and measures azimuthal velocities by Laser Doppler Anenometry. The Maryland experiment has a radius ratio of 0.725, an aspect ratio of 11.47, and measures the torque required to rotate the inner cylinder. The torque on the inner cylinder is observed to be greater than that of the analytical Couette profile and has a complex dependence on the Reynolds number and $\Omega_i / \Omega_o$. The azimuthal velocity profiles also deviate from the laminar Couette profile. Signficantly, super-rotation in the angular velocity has been observed for $1 > \Omega_i / \Omega_o > 0$. In the quasi-Keplerian regime, the angular momentum profiles consist of an approximately constant inner region connected to an outer region approximately in solid-body rotation at $\Omega_o$, which suggests that angular momentum is being actively transported from the inner region to the axial boundaries.