同軸ジェット騒音の研究 : ノズル形状の影響

概要

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The effects of area ratio, inner jet nozzle extension and outer jet nozzle extension on the far-field noise characteristics and the noise source distribution of a coaxial jet were studied experimentally. The distribution of the noise source intensity in the jet was measured by means of reflector-type directional microphone system. The following conclusions were obtained. The minimum noise level for a given nozzle and inner jet velocity occurs at a velocity ratio of nearly 0.5. The axial extension of either of inner or outer nozzle has a large effect on the noise at a small velocity ratio, but it has only a small one at a large velocity ratio, compared to the coplanar nozzle measurement. For the velocity ratio of 0.5,the effect of the axial extension of either of inner or outer nozzle on the noise source distribution occurs at the nozzle exit. For the velocity ratio of 1,the movement of the main noise source which corresponds to the extended axial length is seen in the noise source distribution by extending the outer nozzle beyond the inner nozzle, but the noise source distribution isn't influenced by an inner nozzle extension.
東海大学の論文