Ported Shroud Influence on the Aero-Acoustic Properties of Automotive Turbochargers: Quantification by Means of Simulation and Measurement
* Presenting author
The emerging technology of downsized combustion engines indicates that the conventional turbocharger virtual prototyping methodology should be extended. Not only performance, but also the associated noise ought to be better handled. The latter is mostly affected by the turbochargers’ compressor stage. For instance, widening the operating range, comes at the cost of aero-acoustics problems. The introduction of a ported-shroud prior to the impeller is a workaround to satisfy both performance and noise prerequisites.The aim of this paper is to investigate the acoustical behavior of a centrifugal compressor stage with and without ported-shroud. In order to have a better comparison basis, the study is conducted on two distinct operating points. The method used is a hybrid Computational Aero Acoustics calculation (CAA) consisting of Unsteady RANS (URANS) and acoustic evaluation. Firstly, the compressor stage is CFD modelled followed by locating the noise sources on the basis of the acoustic analogies.The simulation results reveal a clear acoustical dependency on the operating point and the actual ported-shroud function. Compressor map regions and turbocharger frequency ranges are identified depicting a specific pattern of the ported-shroud’s positive effect, i.e. improving aero-acoustics while keeping intact the associated performance. The same pattern is confirmed by measurements.