材料特性に着目したプロペラファンの振動騒音解析

概要

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Designing low-noise air conditioners has recently become one of the most important themes. In particular, the 100 to 450-Hz noise that radiates from resin fans due to the excitation force of the fan motor is a major problem because the radiation characteristic changes depending on the rotational speed and resin temperature. To solve this problem, we propose a noise evaluation index of material characteristics from material and excitation tests and a numerical analysis of the resin fans used for domestic air conditioners. We tested the material characteristics by changing the resin temperature and the direction of resin fiber. Results demonstrate that the Young's modulus changes greatly depending on temperature and direction. We also conducted an excitation test with an excitation machine; results show the vibration mode and noise radiation characteristics of each fan vibration mode. Next, we designed a numerical model on the basis of the two test results and calculated the noise radiation of the fan at low and high temperatures. Results demonstrate that the first vibration mode radiates noise easily, the resonance frequency of the fan changes greatly with temperature change, and the resin fan radiates noise easily at lower temperatures because the change of the A-weighting relative response level of 100 to 450Hz is large. We also show that the A-weighting influence should be considered in a noise evaluation index.
2009-12-25