多翼ファンから発生する広帯域騒音に及ぼす後流渦の影響

概要

論文の詳細を見る
In the prediction theory for the broad band noise generated from a multi-blade fan, the wake was divided into n vortices. Moreover, the characteristic of the sound pressure distributed over the wide frequency domain has been assumed as spatial distributions of the local lift and the frequency accompanying the diffusion of the vortices. As results of the measurement of the internal flow of the fan, it became clear that the noise was related to the wake characteristics of the specific location in the scroll casing where the relative velocity was high. The fan noise operating above the maximum efficiency point was distributed over the domain of 500Hz to 1200Hz. The sound pressure in the domain of the frequency was proportional to the sixth power of the flow rate coefficient, and it was in inverse proportion to the second power of the frequency. When the distribution of the predicted sound pressure level was agreed with the measured broad band noise, it was found that there was no longer influence of wake vortices on the noise in the domains of the high frequency and the low frequency.
長崎大学の論文