Dynamic Mode Decomposition Analysis of the Unsteady Flow in a Centrifugal Compressor Volute

The volute has a significant effect on the unsteady characteristics of the centrifugal compressor. The flow in the centrifugal compressor volute is unsteady and complex. In this paper, the dynamic mode decomposition (DMD) method is used to extract the most dominant flow structures in a turbocharger centrifugal compressor volute under design and mild surge conditions. Large-scale perturbations with synchronic frequencies corresponding to the shaft rotating speed are correctly captured. In addition, nonsynchronic frequency and flow mode in the volute are illustrated. The results show that the high-frequency unsteady flow mode corresponding to the main and splitter blade passing becomes weak in the volute. The development of the unsteady flow mode at the mild surge condition is vividly shown by the reconstruction. Two clear cells in the vaneless diffuser occur under the influence of the volute.