A New Device to Control Axial Thrust of Radial Flow Turbomachinery

Abstract

In high-head and large-sized radial flow turbomachinery some devices, such as balance holes or balance disks, are usually used to balance the axial thrust. But these devices sometimes result in an unbalanced axial force owing to wear or aging of wearing rings. This report puts forward a new device which is quite effective to control and balance the axial thrust with ease and convenience. Even if the above mentioned unbalanced force is caused, it is possible to balance it by this new device even during the operation of a machine. In the former report, it was suggested that it was possible to balance the axial force by controlling the angular momentum of the flow between an impeller shroud and a casing wall. this device uses the phenomenon of angular-momentum defect caused by the wake flow behind several short cylindrical pegs attached onto the casing wall in the rotating flow. The effects of cylindrical pegs on the thrust control are studied theoretically and experimentally.