Effects of Blade Fillet Radius on Aerodynamic Performance and Structural Integrity in a Transonic Centrifugal Compressor

Abstract

In this study, the influence of impeller blade fillet radii on the aerodynamic and structural performance of a 4:1 pressure ratio transonic centrifugal compressor was investigated. Numerical analysis was conducted for four different cases to examine the impact of impeller blade fillet radii on compressor aerodynamics, including a clean edge case without a hub fillet and three cases with varying fillet radii between 1.02 mm and 4.57 mm. In addition, the natural frequency changes due to the increase in fillet radius were analyzed using pre-stressed modal analysis that incorporated the effect of stiffness variation due to centrifugal force, along with static structural analysis for stress evaluation. The results show that the aerodynamic performance increases as the fillet radius is minimized as much as possible. Additionally, results have verified that adjusting the fillet radius can alter the resonance margin. To maximize aerodynamic performance and ensure structural integrity against fatigue failure due to resonance response, proper selection of fillet shape is required.