Numerical analysis of a cross-flow fan with two outlets

Abstract

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.Cross Flow Fans (CFFs) are used in air conditioning and ventilation technology because of their compact design and low noise. In addition, CFFs can provide a uniform velocity profile along the width of the fan. This offers an enormous advantage in applications with large width to diameter ratios as needed. However, as the flow pattern inside a CFF is very complex, classical fan design is not applicable. At present, the design of CFFs is most often based on experimental investigation and empirical experience. In order to investigate the behaviour of these type of fans and its relation to the complex flow structure inside casing and rotor, CFD-simulations are carried out. In this study, transient solutions for a two dimensional viscous and incompressible model of the fan are used to assess the cross flow fan with two parallel outlets. The impact of the outlet configuration on the flow patterns is thereby numerically investigated. It is shown that both the diffuser and the position of the vortex wall play a crucial role to achieve stable and balanced volumetric flows through the two outlets.