ANNULAR FLOW AND DRYOUT IN AN AXIALLY ROTATING PIPE WITH RADIAL FLOW INLET AND EXIT

摘要

Experimental investigation and dimensional analysis are conducted on annular flow in an axially rotating pipe-branch system. Lubricating oil is introduced into a rotating transparent pipe through a radial inlet and ejected into open air via a radial exit branch. The branch-to-pipe diameter ratio, oil flow rate and rotational speed are varied. Changes in oil flow rate and inlet pressure are measured as a function of rotational speed for both spin-up and spin-down processes. Flow visualization is simultaneously performed to observe air-oil two-phase flow behavior and to determine air core diameters in annular flow under various operating conditions. It is disclosed that the intrusion of outside air counter currently with oil exit flow through the branch causes hysteresis in an oil flow rate versus rotational speed plot. Also revealed are the operating conditions for dryout, the occurrence of which is critical to the lubrication of rotating machinery.