Analysis of the impact of the geometry on the performance of an automotive centrifugal compressor using CFD simulations

Abstract

[EN] During the latest years, downsizing in internal combustion engines has moved the operating conditions of the compressor closer the surge limit. Surge onset depends on the geometry of the compressor inlet and is difficult to predict. Unfortunately, the determination of the surge line is essential for engine design and calibration, since surge is an oscillating phenomenon that endangers the turbocharger integrity. This work is addressed to study the impact of placing different geometries, namely a tapered duct, a convergent-divergent nozzle and a divergent nozzle in the compressor inlet on different compressor parameters such as stability, efficiency and noise emission. 3D-CFD simulations are performed using the commercial code STAR-CCM+ at both near-surge conditions and high mass flow rate, focusing on the flow structures generated by each configuration. The results are compared with corresponding experimental tests and show a meaningful sensitivity of geometry to the performance, indicating potential benefits of using some of these geometries in turbocharger configurations.