Unsteady flow at the outlet of the high specific speed centrifugal compressor impeller

The unsteady flow at the outlet of the high-specific-speed mixed-flow impeller was studied. The flow is strongly influenced by the impeller blading. On the other hand, the flow influences the performance of the stationary vanes downstream of the impeller. The flow path at the outlet of the mixed-flow impeller is inclined to the axial direction and is curved in the meridional plane. The study was carried out to develop the 30 MW centrifugal compressor. This compressor is used in the field of coal gasification, geothermal power generation, etc. The distributions of flow velocity, pressure, and temperature of three-dimensional flow were measured using a high-sensitivity pressure transducer and a total temperature probe. The flow was surveyed across the entire passage at about ten axial locations including the endwall boundary layer. A theoretical analysis was also carried out using the linearized Navier-Stokes equation.