サブキャビテーション域におけるねじり振動翼の特性とフラッタ限界

概要

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The torsional flutter margins of a pitching hydrofoil in the subcavitation region under various flow and vibrational parameters, i.e, the angle of attack, the cavitation number, the reduced frequency and the torsional axis, were expermentally investigated. The cavitation aspects of the hydrofoil are shown using high-speed photographs. The unsteady lift and moment were measured using a torsional vibration-apparatus with load cells which can eliminate the mechanical inertia force and moment of the pitching hydrofoil. The type and intensity of the separation on the hydrofoil have a large influence on the cavitation aspect, the unsteady fluid force and the flutter margin in the subcavitation region. In the case of nonseparation. an unstable range of the flutter exists neither in the noncavitation region nor in the subcavitation region. In the case of separation in the noncavitation region, the flutter margin expands to the higher reduced frequency side as the angle of attack increases, and in the subcavitation region, these flutter margins remain until the cavity length reaches the mid-chord. However, the flutter margin slides toward the higher reduced frequency side maintaining the same width as the cavity length extends from the mid-chord to the full chord.
一般社団法人日本機械学会の論文
1997-09-25