2430 斜流ポンプに発生するディフューザ旋回失速の内部流れ(S41-5 流体機械に関連した複雑内部流動の解析と計測(ポンプ),S41 流体機械に関連した複雑内部流動の解析と計測)  [in Japanese] 2430 Unsteady Flow in a Mixed-Flow Pump Under Diffuser Rotating Stall Conditions  [in Japanese]

This paper presents the unsteady internal flow in a mixed-flow pump with a vaned diffuser. Tested pump has a positive slope of the head-flow performance curve at about 65% flow rate of the best efficiency point due to rotating stall in the vaned diffuser. In order to investigate this phenomenon, pressure fluctuation measurements and dynamic PIV measurements have been performed. It is found that the strong vortex develops at the leading edge of the diffuser vane and backflow from the outlet of the diffuser vane is induced and then the backflow conflicts against the outward flow from the impeller. As the result, the periodical unsteady flow is obtained. Based on PIV pictures, it is clarified that a stall occupies four passages (backflow area is three-passage and the stall core occupies one-passage) out of thirteen passages.