Investigation of the flow in a small-scale turbocharger centrifugal compressor

This paper presents an experimental and numerical study of the flow in a 1:1 scale, automotive turbocharger centrifugal compressor. Particle image velocimetry measurements have been carried out in the vaneless diffuser at 50% of the design speed. The challenges involved in taking optical measurements in the current small-scale compressor rig are discussed. The overall stage performance and the measured diffuser flow are compared with the results of steady-state computational fluid dynamics calculations. A good agreement between the computational fluid dynamics and the experimental results demonstrates that the numerical methods are capable of predicting the main flow features within the compressor. The synthesis of measured and predicted data is used to explain the sources of the flow and performance variations across the compressor map, and the differences in loss production between small and large compressors are highlighted.