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Abstract The demand for HVAC chiller systems in commercial centers is ever-increasing. Chillers with centrifugal compressor units produce high-frequency noise, a significant problem that needs to be addressed. The blade passing frequency is the primary noise source a centrifugal compressor generates. The objective of this paper is to investigate the vibro-acoustic performance of an oil-free two-stage centrifugal compressor with magnetic bearings via numerical modeling. The noise source is obtained using the time-variant pressure data from the unsteady RANS simulation of the aerodynamic parts of the compressor. The unsteady pressure data produced is integrated onto the corresponding solid domain of the compressor, and a harmonic response analysis is carried out to quantify the vibration energy transferred through the compressor system at specific engine orders. Finally, the far-field sound pressure level generated by the compressor is quantified for all engine orders up to 10kHz. Additionally, experimental testing of the centrifugal compressor in a anechoic chamber is carried out to determine the sound pressure level and validate the numerical methodology. Results indicate that numerical findings are in good agreement with the test data, indicating that the developed methodology is capable of accurately predicting the tonal noise in the current application. Furthermore, results show the tonal noise generated is primarily dependent on the number of main blades and splitter blades of the impeller, revealing those components to be the primary source of compressor noise.
Krishna et al. (Mon,) studied this question.