Abstract
The region where pressure rises and the rate of the rise were examined in a centrifugal blower casing which has no diffuser and large tongue clearance. At the design point, the pressure recovery in the scroll was about 45 percent. The remaining 55 percent were recovered in the section between the scroll end and exit duct. This section acted as a high-performance diffuser. It was concluded that centrifugal force produced by secondary flow and boundary layer section was the main cause of the high pressure recover. Moreover, it was suggested that the flow conditions from the scroll toward the exit duct were closely related to the low flow rate characteristics of the blower.
