CENTRIFUGAL STAGE PERFORMANCE PREDICTION AND VALIDATION FOR HIGH MACH NUMBER APPLICATIONS
Steve Kowalski is an Aero-Thermo Engineer in the Research and Development Department of DresserRand. His responsibilities include the design, development and analysis of aerodynamic components of centrifugal compressors. He has been employed at Dresser-Rand since 2007. He holds a B.S. degree from Michigan State University (Mechanical Engineering, 2002) and an M.S. degree from Michigan State University (Mechanical Engineering, 2005). Prior to joining Dresser-Rand, he worked as a teaching/research assistant at Michigan State University.
The Influence on the Meridional Impeller Shape on the Energy-Transfer in Centrifugal Compressors
Three radial flow impellers were tested having an elliptic blade shape and identical blade geometry at inlet and exit but different shapes of the meridional contours. The compressor maps with pressure ratios up to 2.9:1 are compared using time-dependent measurements of the static pressure at the shroud and of the flow angles closely downstream of the impeller. From these measurements, the influence of impeller shap on the jet-and-wake flow is discussed. It is shown that with increasing impeller length, the wake zone at the suction side of the blades can be only partially influenced and friction losses become dominant with respect to compressor performance. A smooth curvature of the meridional cross section of the impeller channel leads to a better jet-wake ratio at impeller exit. Accordingly, the performance characteristic shows higher values especially when the mass flow is increased.Copyright © 1980 by ASME
A Blockage Model for Centrifugal Compressor Impellers
This paper presents and discusses the results of an analysis in which the blockage distributions of four impellers were deduced from shroud static pressure measurements. The purpose of the analysis was to provide a means of estimating blockage for the jet-wake flow model for use in impeller design calculations. A parameter was investigated for correlating the blockage values against the combined effect of diffusion, curvature, and Coriolis acceleration. It was found that gross blockage accumulation correlates against this parameter with an uncertainty in blockage of ± six percentage points. Up to the point of the axial-radial bend of the flowpath, the analysis shows that blockage is controlled equally by diffusion, flowpath curvature, and the combined effect of blade curvature and Coriolis acceleration. In the radial portion of the impeller, further increase in blockage is controlled by Richardson number.