Effect of impeller blade trimming on the performance of a 5.5:1 pressure ratio centrifugal compressor

Abstract

Centrifugal compressor blade trimming can be used for the purpose of changing the performance characteristics of an impeller or allowing a single impeller design to be used for a range of operating conditions. There are different methods of impeller blade trimming that may be employed to change the impeller flow rate, the pressure ratio, or both. In this study, computational fluid dynamics is used to model the effects of two different methods of blade trimming on a single centrifugal compressor design. Impeller performance characteristics and analysis of the flow field are presented for a series of trims. Trimming the passage area from inlet to outlet along the meridional length reduced the flow rate of the impeller and narrowed the effective operating range. The head coefficient and efficiency relative to the choked flow coefficient remained unchanged as the passage area is reduced; however, the flow rate is reduced by a greater amount than the inlet area is reduced. Trimming the impeller blades by shifting the shroud profile in the axial direction caused the head coefficient to be reduced while maintaining a constant flow coefficient. This method of trimming is limited by choking in the radial portion of the passage, and the head coefficient for the impeller studied was able to be reduced by up to 15% before further trimming limited the choked flow rate.

Electric Boosting and Energy Recovery Systems for Engine Downsizing

“…A new technology is proposed by Swine and Engeda [31] to modify the impeller design by trimming the impeller. This technology assists in maintaining the efficiency of the compressor high for longer time.…”

Flow Simulation and Model Analysis of Efficiency and Pressure Ratio Behaviors in GT4086 Turbocharger Compressor

“…[8] Impeller optimization is an interesting research area. A novel study by Swine changed the impeller design [12,13] using axial, radial and stream-wise directions of correction. This so-called trimming method begins with a scratch design of the impeller and continues to make the design more delicate, which affects the impeller boundaries in different directions.…”

Improving Centrifugal Compressor Performance by Optimizing the Design of Impellers Using Genetic Algorithm and Computational Fluid Dynamics Methods

“…The method proposed by Swine to change the impeller design [10,11], namely trimming, begins with a scratch design of impeller and proceeds to make it more delicate. This process can affect the boundaries of impellers in different directions.…”