Unsteady flow phenomena in an axial flow compressor.

A broad investigation of the unsteady flow phenomena which occur in an axial flow compressor is presented. It is based on an analysis of hot wire measurements of the time variation in velocity at fixed points in the flow through a single stage machine with three blade rows. The study has been confined mainly to the "potential flow" unsteadiness due to the rotor movement and the effect of wakes from one blade row interacting with downstream rows. A general experimental investigation of the compressor blade wakes is included. The results are compared with velocity distributions calculated from existing potential flow models of the flow through a cascade, and a new model lased on the approximations of thin aerofoil theory is developed by the author. Consideration is given to the development of a model of a blade wake and the author's potential flow model is extended to include a wake and boundary. layer thickness effect. Also included is an account of a brief experimental investigation of the noise generated by the compressor due to blade row interaction effects