傾斜した平板翼から発生するエオルス音に関する実験的研究

概要

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The Aerial Noise generated from the inclined plates were investigated experimentally. The wake vortices which generate from each edge of the body and shed alternatively, it's call Karman vortices, govern the aerial noise and the flow induced vibration. At first, we found that the noise level becomes largest not at 0 inclined angle, two dimension flow condition, but at 5 to 10 degree inclined. And it is found that the span wise length of each wake vortex becomes about 3times large at the case of 5 to 10 degree to the case of 0 degree. When the inclined angle becomes larger than 10 degree, the noise level and the span wise length of wake vortex becomes small. The second, the frequency of noise is not coincide to that of the wake vortex shedding. The frequency of the noise becomes low with the inclined angle, but that of wake vortices becomes high that is represented by the frequency of the maximum velocity fluctuation in the wake, that is, the main shedding vortex does not make the aerial noise. The span wise length of the wake vortex becomes large not at the frequency of maximum velocity fluctuation, but at the other frequency at which the phase of cross-correlation is 180 degree. And the span wise length of wake vortex becomes large and the frequency becomes low with inclined angle. That is, the aerial noise is closely related to the vortex that the phase is coincide along the span.