Abstract
In centrifugal compressor or blower, operation becomes unstable as flow rate reduces because of self-exciting phenomena like rotating stall or surge. This study describes unsteady phenomena in the static pressure field due to rotating stall observed in a radial vaneless diffuser of a centrifugal blower. In the experiment, static pressure measurement was conducted using pressure transducers attached on the diffuser wall. The data was acquired slowly changing the operation region from stable to unstable by throttling the flow control valve. As result, by means of spectrogram and cross-correlation analyzes, transient process under unsteady condition in the diffuser was made clear.
