Multi-physical Modeling of Noise and Vibration Due to Refrigerant Discharge in Hermetic Compressors

In high-pressure shell hermetic compressors, the refrigerant discharge flow from the compression chamber(s) involves interactions between interior acoustics, turbulent fluid flow and structural vibration. To study and optimize the compressor shell and compression discharge process, a comprehensive multi-physics simulation model encompassing the thermomechanical, fluid flow and vibro-acoustics aspects of hermetic compressor has been developed. The thermomechanical model is based on a deterministic compressor chamber model. Whereas the interior fluid flow is modeled using a CFD approach, and the resulting broadband noise and vibration is modeled via a fluid-structure interaction (FSI) interface. The narrowband noise and vibration effects due to periodic compressor discharge pulsations are estimated by using finite element analysis (FEA). The thermomechanical model provides instantaneous pressure traces from the compression process which are used as boundary conditions for either fluid or acoustic domain to enable the coupling with FSI and vibro-acoustics simulations. The comprehensive simulation model is utilized to understand the physical reasons behind NVH effects in a hermetic rolling-piston compressor for air-conditioning applications.