Characterization of Flow Structures in the Upper Cavity of a Rotary Compressor

As hundreds of millions of Air conditioning (AC) systems are produced each year, and many use rotary compressors as heat pumps, optimizing the flow inside the rotary compressor to improve its reliability and efficiency becomes a key issue. However, the flow in a rotary compressor is extremely complicated due to the complex internal structures’ geometry and high-speed moving parts. The present work studies the flow field above the rotor/stator in a rotary compressor and two major effects are identified. One is the swirling jet produced by the high-speed rotating rotor. Another is the rotating disk effect induced by the top of the high-speed rotating rotor. The CFD results, validated by experiments, show an inner recirculation zone above the rotor that creates a downward velocity component above the rotor and an outer circulation zone above the stator. With the CFD results and the experimental observations, identified is the transport path of oil droplets in the rotary compressor’s upper cavity. This discovery helps to reduce the lubricant oil escaping from the compressor.