多翼送風機内非定常流れにおけるスペクトル別分解と再構成

抄録

Multi-blade fan can achieve high pressure and flow rate despite of its small size. However, the fun has still has drawback on the noisegeneration. Although it is required to understand the cause of noise, it is difficult to understand the internal flow of a multi-blade fan because of its complexity. From the experimental results and analysis results, the multiblade fan in the present study was noisy around 1 kHz. The static pressure data obtained by CFD is filtered with narrow band pass filter, and only the frequency around 1kHz is extracted and analyzed. As a result of visualization, the change in static pressure is small at a location shifted by about 90 ° from the tongue rotation span of the blade, the positive / negative pressure changes at a location shifted by 270 °, and the static pressure change is large at other locations. Since the length of the scroll casing is close to the wavelength of the sound wave, it is assumed that the noise around 1kHz is due to the resonance phenomenon. The visualized result is similar to the behavior that assuming a resonance phenomenon. In the future, it will be important to conduct detailed acoustic analysis to clarify that 1kHz noise is a resonance phenomenon.