The Advanced Annular Couette Centrifuge (AACC)

An increase in the effective gravity of a centrifuge for aqueous solutions by more than an order of magnitude may be achieved by the addition of an inner cylinder co-rotating with the outer cylinder but at a larger angular speed. Recent experiments conducted at PPPL have shown that rotating fluids in such a device can have extremely low levels of turbulence, essential for efficient separations. This is enabled by modification of the axial boundaries which greatly reduce the secondary flows. In specific regimes of operation relevant to an advanced centrifuge, turbulence and angular momentum transport can be reduced to nearideal levels. The Advanced Annular Couette Centrifuge (AACC) is distinguished in three regards: sheared laminar rotation, split axial boundaries and intentional asymmetry to drive controlled secondary circulation. The core design is based on that of the circular Couette apparatus. It has been known for many years that a wide range of flow regimes, from highly turbulent to purely laminar, can be generated in Couette devices and are dependent on the ratio of the cylinder radii and the ratio of the cylinder speeds. It has recently been discovered that there is a surprisingly quiescent regime, the so-called quasi-Keplerian regime due to its astrophysical relevance, in which the inner cylinder rotates faster than the outer cylinder but not so fast as to generate turbulence. A device operating under these conditions possesses the ideal qualities for an ultra effective centrifuge.