103 傾斜した平板翼から発生する空力音と後流渦の関係 : 後流渦のスパン方向特性の影響(空力騒音の解析)

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The three dimensional structure of the wake vortex was investigated in relating to the aeolian tone from the inclined flat blade, which is installed in the uniform flow from zero to thirty degree of the inclined angles with upper and lower wall. It was pointed out that the aeolian tone is largest not at zero, but at ten degree of the inclined angle. The pressure fluctuation to generate the aeolian tone on the surface of the blade is closely relating to the formation of the shedding vortex in the wake. The strength of the vortex is almost constant in small inclined angles, but the scale of it in span direction becomes large at small inclined angles. The span wise correlation of the wake vortex at zero inclined angle is only restricted near the position of that the shedding vortex forms and gradually decreased with the retarded time. But the correlation at small inclined angle is moved in span direction with the span-wise velocity in the dead air region. The wake vortex is classified in span direction to the locally small cluster and the large one. The aeolian tone is closely related to the large cluster of the wake vortex. The delay of the wake vortex formation is occurred in span direction with the large cluster. The estimation of the correlation length is proposed in relating to the delay of the wake vortex formation. The estimation of aeolian tone by the correlation length is good agreement with the experiments.
2009-07-08