Abstract
A centrifugal fan with forward curved blades can give a large angular momentum to the fluid, but it doesn't have better efficiency. In this paper, design method to get a shape of volute casing with the best performance was treated. The experiments and numerical calculations were done using 2 shapes of impellers and 21 shapes of volute casings. Pressure distributions along the volute casings were also measured. From these results it was made clear that there a magnifying angle and a circumferential angle be able to have the largest discharge and the best efficiency. From these results the design method of the best type of volute casing was considered. These results were also made sure by the results of numerical calculations.
