Prediction of noise from an automotive turbocharger centrifugal compressor using three-dimensional computational fluid dynamics

Abstract

The noise generated by centrifugal compressors for automotive turbochargers consists of narrow and broadband components. Narrowband noise occurs near integer multiples of the shaft rotational frequency, and the prevailing order is typically equal to the number of main impeller blades (impeller blade-pass frequency). However, for a centrifugal compressor without a ported shroud recirculating casing treatment, such as the current contemporary configuration, broadband noise is dominant, typically in the 4–12 kHz range. This study applies a three-dimensional computational fluid dynamics model to this compressor installed on a steady-flow turbocharger stand. As the compressor flow rate is reduced at constant rotational speed, broadband noise is elevated as a result of deterioration of the flow-field near the inducer (inlet) of the impeller, due primarily to flow separation from the suction surface of impeller blades. Detached eddy simulations provide reasonable agreement with the corresponding experimental measurements in terms of capturing performance, as well as acoustics, thereby shedding insight into this noise source mechanism associated with such flow separation.