Numerical investigation to small high speed centrifugal compressor

The performance and three-dimensional viscous flow-field of the centrifugal compressor stage in a micro-turbine are investigated numerically. The primary parameters of the compressor are revealed. The numerical results indicate that the stage is endowed with steep working characteristics. In the whole flow range, the impeller operates under subsonic condition and the radial diffuser operates under transonic condition, thus the choked mass flow rate is determined by the throat area of the radial diffuser. The interactions between different through-flow parts (impeller, radial diffuser, axial diffuser) exert significant influence on the flow in the two diffusers and result in a bigger separation range near hub elements, which dominate the performance and stability during the whole stage.