Numerical study of the efficiency of an axial compressor rotor operating at low Reynolds numbers

This paper presents numerical studies on an axial compressor rotor across 16 NACA65-based configurations. The study focuses on rotors with compression power below 100 kW, operating at Reynolds numbers under 750,000. Numerical simulations examined variations in blade angle, solidity, thickness, and rotor size using a validated numerical model. Performance maps were generated for each geometry at six rotor speeds to assess regulatory potential. Results show that rotors with high incidence angles offer the most flexibility, with efficiency losses under 18 % across the range. However, rotors with the highest blade angles had the lowest efficiency (90 %) and the steepest drop (53 %), indicating lower stability. Within the studied Reynolds range, primary losses stemmed from profile losses and boundary layer separation on the blade's suction side. Secondary effects, like tip leakage vortex and hub corner separation, had a less significant impact. Findings suggest that increasing Reynolds numbers through rotor size expansion has less impact on efficiency than increasing it via a broader speed range. This insight aids in designing more efficient axial compressors, optimizing regulatory control while minimizing efficiency losses. • 16 different geometrical configurations of the axial compressor rotor - numerical tests. • Impact of blade: solidity, thickness, angle and rotor size on polytropic compression efficiency was investigated. • The regulatory potential was also investigated by determining full performance maps for 6 different rotor speeds. • Blade solidity and blade angle had the most significant impact on the decrease in efficiency.