THREE-DIMENSIONAL NUMERICAL SIMULATION OF A CENTRIFUGAL COMPRESSOR OPERATING WITH SUPERCRITICAL CO2

Resumo

Centrifugal compressors performance can be benefited by the low viscosity, high density and
small compression work of the supercritical CO2. The design and aerodynamic optimization of such
devices must take into account the flow behaviour under these conditions, that can be ensured by high
fidelity three-dimensional computational fluid dynamic simulations. This work presents a numerical

modeling and simulation of the highly turbulent, compressible flow inside the impeller of the proof-of-
concept supercritical CO2 microcompressor experimentally tested at Sandia National Laboratories. The

steady state solution was obtained by solving the three-dimensional Reynolds Averaged Navier-Stokes
equations using the comercial software ANSYS CFX. The equation system was closed by the Shear

Stress Transport turbulence model. Thermodynamic properties were evaluated through the Aungier ver-
sion of Redlich-Kwong equation of state, providing better accuracy near critical point condition than its

original version. A grid convergence study was conducted to verify possible numerical error induced by
computational domain discretization. Finally the numerical method was validated against experimental
data and the flow characteristics, typical to centrigual compressors, like the suplementary depression and
leakage flow losses was discussed.