The challenging problem of noise generation and propagation in automotive turbocharging systems is of real interest from both scientific and practical points of view. Robust and fast steady-state fluid flow calculations, complemented by acoustic analogies can represent valuable tools to be used for a quick assessment of the problem during e.g. design phase, and a starting point for more in-depth future unsteady calculations.
Thus, as a part of the initial phase of a long-term project, a steady-state Reynolds Averaged Navier-Stokes (RANS) flow analysis is carried out for a specific automotive turbocharger compressor geometry. Acoustic data are extracted by means of aeroacoustics models available within the framework of the STAR-CCM+ solver (i.e. Curle and Proudman acoustic analogies, respectively). This part of the work focuses on the discussion and comparison of the aeroacoustic models, and their suitability towards predicting flow and acoustics trends corresponding to the operating conditions investigated. However, given the unsteady nature of acoustics, the project will have to develop towards an investigation of the problem using more expensive, but more accurate, Large Eddy Simulation (LES) calculations.
An entire compressor map with 80 operating conditions was simulated, yielding trends in the behaviour of the performance parameters for the analysed compressor. Detailed results calculated on the same compressor speed-line for one design and one off-design operating conditions are presented in terms of time-averaged pressure coefficient, Mach number, and acoustic power distributions. A total acoustic power map has been generated based on the outcome from the Curle and Proudman acoustic models, giving an indication of the noisiest operating conditions.