Cross-flow fan design guidelines for multi-objective performance optimization

More than one century has passed since Mortier's first cross-flow fan patent in 1891, but the design is still based on empirical considerations and on the re-adaptation of previously developed configurations. The complexity of the flow field inside the machine is the main reason for the lack of an established design procedure, because the characteristics of the eccentric vortex that forms within the impeller are deeply influenced by the geometry of the impeller and also of the casing. In this paper, the objectives that should be pursued in the design procedure are discussed and defined, and guidelines for cross-flow fan design are determined through the analysis of an experimental database of fan performance and efficiencies, which is obtained by the systematic variation of the most important geometric parameters of the casing in combination with different impellers.