Flow Loss Mechanism and Modeling in a Centrifugal Compressor Casing

The current work presents a simplified flow loss model of centrifugal compressor casing flow. The model can be used to estimate the flow losses and air flow rate through the casing under arbitrary casing geometry definitions. Numerical simulations of a turbocharger centrifugal compressor are presented and experimentally validated, with excellent agreement between the model and experimental data. The numerical results were used to investigate the different casing flow loss mechanisms, and the major sources of flow loss in the casing were identified. The simulations indicate the casing flow losses are due to a combination of dividing flow loss, expansion flow loss and friction loss. The dividing flow loss, caused by a portion of the main flow entering the casing slot, is the major source of flow loss, while the expansion flow loss, caused by the expansion flow returning from the slot to the casing cavity, is the second most important source of flow loss. By simplifying the casing into a 2-D configuration, the flow loss coefficient k in the dividing flow and expansion flow is simplified as a function of the casing geometric parameters and dividing flow loss and expansion flow loss models are developed and numerically validated. The results of this work are a valuable new tool to rapidly evaluate casing designs with low computational costs.