遠心圧縮機内部に発生する旋回失速の流量低下に伴う過渡特性

抄録

The characteristics and the transition process of rotating stall behavior, which were followed by the decline of flow rate, in centrifugal compressor with vaned diffuser were investigated through experimental analysis. Measurements showed that impeller and diffuser rotating stall occurred at 55 Hz and 25 Hz, during off-design point at ϕ=0.14. Furthermore, stage stall, which rotated within impeller and diffuser passages, occurred at 22 Hz and ϕ=0.10. According to the measurement of the pressure and velocity at the diffuser inlet, the flow field was divided into three behaviors at ϕ=0.10. At the “pre-stage stall” condition, the diffuser stall was enlarged and hub-side local blockage emerged behind the scroll tongue in vaneless space. This blockage induced a static pressure rise on the shroud wall and a deceleration of radial velocity on the hub side. The diffuser stall moved into the impeller passage because of the blockage and caused the stage stall.