On cross-flow fan theoretical performance and efficiency curves: an energy loss analysis on experimental data

Contrary to conventional turbomachinery, cross-flow fan flow field is non-axisymmetrical and its complex configuration strongly affects performance and efficiency characteristic curves. The formulation of a theory on cross-flow fan operation is made even tougher since the strength and the eccentricity of the vortex that forms within the impeller are deeply influenced by the geometry of the impeller and of the casing as well. In this paper, a numerical reconstruction of the flow field, validated against an extensive systematic database of global and local experimental measurements, is analyzed. The aim is to achieve a general interpretation of performance and efficiency curves, and to lead them back to one theoretical archetype, whatever the fan configuration being considered.