Effects of Inlet Pressure Distortion on the Performance and Flow Field of a Centrifugal Compressor at Design Condition

Abstract

The present paper presents experimental results on the effects of inlet total pressure distortion on the performance and flow field of a centrifugal compressor. The total pressure at inlet is artificially distorted by means of a perforated sheet, which is supported by a support mesh. A total of eleven configurations, including clean inlet configuration, are tested. Performance measurements and impeller inlet and exit flow studies are carried out. The distorted inlet flow causes loss of energy, reduction in the maximum flow coefficient and perceptible decrease in the stable operating range of the compressor when compared with undistorted inlet flow. The reduction in stable operating range is the highest for 150° Distortion and the least for 4x22.5° Distortion. In radial distortion group, tip distortion has more detrimental effect on the operating range, energy coefficient and efficiency. The mass averaged total pressure at the impeller exit is the highest for clean inlet and the lowest for Hub+90° Distortion. The circumferential distortion has more adverse effect than the radial distortion on the flow parameters. The combined radial and circumferential distortion (Hub+90°) has the worst effect on the mass averaged flow parameters. As the Distortion Index (DI) increases, the mass averaged total pressure at exit stations decreases. Distortion sector angle of 60° having the lowest total pressure is found to be the critical sector for circumferential distortion configurations. As the Distortion Correlation parameter, DC(60) increases, the mass averaged total pressure for circumferential distortion configuration decreases.