An Approximate Investigation of the Off-Design Performance of a Turbo-Compressor Stage

Abstract

Turbine or compressor stages are often designed by comparison with a mathematical model with a perfect fluid and a particular flow quantity.

Empirical correction factors are required for the various sources of discrepancy between the mathematical model and an actual stage, such as wall and blade friction losses and tip clearance losses, but such models are of considerable use as a basis of comparisons.

In multistage compressors or turbines that are required to operate over a wide range of speeds and flow quantities, the individual stages are required to operate over a wide range of velocity ratios. So far no satisfactory model has been proposed for the effect of variation of flow quantity from the design conditions.

This paper considers the simple problem of an isolated stage working in a long, parallel annulus with a perfect incompressible fluid.