Cavities formed by discs contained within a shroud, either of which may be rotating, are a common feature of turbomachinery. Associated design problems are typically the determination of the cavity air supply required to control temperature, and of the power required to overcome the drag generated by the rotating components.

ESDU 15012 gives a description of the principal flow characteristics in a variety of rotating characteristics. Cavity configurations considered include:

• closed rotating cylindrical and annular cavities

• rotating cavities with net radial outflow

• rotating cavities with net radial outflow

• rotating cavities with axial throughflow.

The purpose of ESDU 15012 is to provide an understanding of the flow in cavities, an introduction to generalised analysis and to describe the role of Computational Fluid Dynamics as the principal flow-analysis tool currently used for such flows.