J0501-1-1 小弦節比翼列ディフューザにおける二次流れの挙動解析(流体機械の研究開発におけるEFD/CFD(1))

概要

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A low-solidity cascade diffuser was proposed for achieving a wide operating range as well as a high pressure ratio. However, noise increased by means of LSD due to vortex shedding from the LSD blade surface. The objectives of the present study are to show that the noise can be reduced effectively by means of a small tip-groove located at the shroud side alone without deterioration of the LSD performance, and to clarify the mechanism of high blade loading of the LSD blade with the shroud side tip-groove limited near the LSD blade leading edge. The effect of a small groove on the stagnation area, the vortex generated in the tip groove and the secondary flow behavior on the suction surface of the LSD blade and the diffuser walls as well are analyzed numerically. It is found that the formation of the recirculating secondary flow generated additionally and significantly by the shroud tip-groove is a key point of the high LSD performance.
2009-09-12