Performance implications of backswept angle in supercritical CO2 centrifugal compressors

The performance of a supercritical CO2 centrifugal compressor is critically influenced by the backswept angle of the blades. This study investigates the aerodynamic and thermodynamic impacts of varying backswept angles, on the performance parameters such as pressure ratio, isentropic efficiency, flow characteristics, and shaft power requirements. Three-dimensional viscous compressible flow through a centrifugal compressor at steady state is numerically simulated with real gas effects at varying mass flow rate. After the essential grid independency test, the numerical methodology is validated with experimental data. At all mass flow rates, the efficiency and pressure ratio decrease with an increase in the backsweep angle, particularly from 90°. Higher backsweep angle configurations exhibit severe flow separation with energy loss. Due to the larger aerodynamic loading, smaller values of backswept angle require a relatively higher shaft power than configuration with a higher backsweep angle.