Study of cross-flow-fan internal flow by flow visualization (Discussion of measured results by particle-tracking velocimetry)

The internal flow of a cross-flow fan (CFF) is affected strongly by an eccentric vortex generated in the CFF. However, the mechanism of growth of the eccentric vortex is not clear. Therefore, a design method for the CFF has not yet been established. In order to study the internal flow of the CFF, the authors measured the velocity distributions by particle-tracking velocimetry (PTV) using an experimental apparatus for water flow visualization. The pathline images photographed with a digital still camera were analyzed by a computer program developed by one of the authors in order to obtain velocity distributions. Before the measurements of the internal flow were carried out, the measurement accuracy of this PTV was examined, and it was confirmed that this PTV was useful to this study. The measured results on the internal flow were discussed from several points of view and useful information on the flow field of the CFF was obtained.