An Experimental Study on the Rotating Stall in Vaneless Diffuser of Centrifugal Blower with Radial Type Impeller

반경류형 회전차를 가진 원심송풍기의 깃이 없는 디퓨저 내의 선회실속에 관한 실험적 연구

The vaneless diffusers are widely used in industrial centrifugal compressors which are required to operate within a wide flow range. When very high pressure gases are handled by centrifugal compressor. rotating stall is a serious problem because of the occurance of large aerodynamic exciting forces. Rotating stall mostly often occurs in the impellers but it can occur in vaneless diffusers as well. In this experimental study, the rotating stall in vaneless diffuser with radial type centrifugal impeller was measured by changing the flow rate with I-type, X-type hotwire. As the result, it was cleared which type of rotating stall of the impeller stall would occur and how many stall cells would appear relating with the flow rate. As the flow rate reduced, the propagation speed of rotating stall was reduced. But the stall cell number unchanged with respect to the flow rate.