Abstract
An axial-flow fan causes anomalous phenomena such as rotating stall and surging. From past researches, it has been found that casing treatments are effective in order to avoid these anomalous phenomena. The aim of this study is to verify effect of a self-circulation on the performance of an axial-flow fan. In this paper, the correlations between discharge and pressure, discharge and efficiency for total pressure are shown in each case of casing treatments. It is found that the casing treatment with holes is effective to delay the stall point and self-circulation is effective from the viewpoint of efficiency for total pressure. It is suggested that the self-circulation is preferred as long as both delaying stall point and efficiency for total pressure should be concerned.
