The blade shape design is one of the most important factor for improvement of efficiency or noise reduction of a centrifugal fan. However, it is not easy to analyze flow through impeller blades both theoretically and experimentally. This paper describes an experimental investigation of flow through impeller blades of a fundamental model of the centrifugal fan and a multi-blade fan by means of quantitative method of visualization. The results obtained show the instantaneous profiles of flow through blades.
