2414 動翼可変軸流ファンでのモーダル型旋回失速発生過程に及ぼす翼端隙間流れの影響(S41-2 流体機械に関連した複雑内部流動の解析と計測(失速・はく離・翼列干渉),S41 流体機械に関連した複雑内部流動の解析と計測)  [in Japanese] 2414 Effect of Tip Clearance Flow on a Modal-Type Stall Inception in a Variable-Pitch Axial-Flow Fan  [in Japanese]

An experimental study has been carried out to clarify flow mechanism behind the modal-type stall inception. Pressure fluctuations on the casing wall showed that the interface between the incoming and tip clearance flows, which extends from the suction side near the rotor leading edge, disappears at the mid-passage at the stable operating points. This interface therefore does not become parallel to the leading edge plane. The rotor blade is overloaded, and the tip clearance backflow initiates from the rotor trailing edge when the tip incidence angle exceeds the critical value. The backflow extends upstream as the flow rate decreases, and the interface between the incoming and back flows becomes parallel to the leading edge plane at the stall inception point. We concluded from these results that the tip clearance-back flow from the trailing edge affects the modal-type stall inception.