Design of Low Noise Compressors Using NASA CFD

This paper discusses the application of OVERFLOW to a rotary compressor for the purpose of designing high efficient low noise air compressors. OVERFLOW, a computer program originally intended for external flows, was applied to an air compressor where the flows are internal. The paper explains how OVERSET meshes are constructed for rotor geometry where the clearance is extremely small in relation to the overall dimensions of the compressor. OVERFLOW dates back to the 1980's when a CFD solver was needed to model the aerodynamics of the Space Shuttle. At the time there was no solver capable of modeling the full flight dynamics of the Space Shuttle. Over the past 3 decades OVERFLOW has gained in popularity becoming a major CFD code in the aerospace community. This paper summarizes the findings in a technology development effort to determine if OVERFLOW could be used to simulate internal flows inside an oil-free screw compressor where the gas flows are among the most challenging to model with CFD.