Discussion: “Rotordynamic Force Prediction of Centrifugal Compressor Impellers Using Computational Fluid Mechanics” by J. J. Moore, D. L. Ransom, and F. Viana

Abstract

The authors are to be commended for an interesting demonstration of computational fluid dynamics (CFD) methods in the analysis of rotordynamic forces for impellers in centrifugal compressors. CFD approaches clearly represent the future for this important calculation. As they state, data are vitally needed to anchor predictions for impeller coefficients for compressors. In fact, better data would also be helpful for pump impellers. The data of Bolleter et al. [4] yield whirl frequency ratios that range upward from 0.75 to 2.2. To the extent that the destabilizing forces arise from fluid rotation, WFR cannot exceed the average circumferential velocity ratio, and more reasonable values would be on the order of 0.5 (as predicted by the authors).