Fan Laws, The User And Limits In Predicting Centrifugal Compressor Off Design Performance.

Abstract

The fan laws, particularly what the limits are in their use is described. The derivation is covered very briefly. To help understand some of the fan law uses, centrifugal impeller characteristics are covered, particularly some of the things controlling the shape of the curve. A discussion of the fan law deviations in an individual impeller is covered. Multistage centrifugals are covered using two, four, and six stage configurations. A set of stage curves are made up for use of the study. These curves reflect two basic impeller designs. The designs result in a high (15 percent) and a low (five percent) head rise. Also included is a study where the effect of molecular weight is presented. Speed variations are covered and compared to the fan law prediction with the deviations being shown.