Abstract
A blower is a machine that gives rotational energy to gases from the impeller and discharges them from the outlet. Among blowers, the centrifugal turbo-blower is good at producing high-pressure and running with high efficiency. However, the noise of the blower is so large that it is required to reduce the noise. The centrifugal turbo-blower targeted in this research is especially noisy in low flow and high flow. Until now, this research group revealed the turbulence noise source in high flow and reduced the noise of the blower. On the other hand, the turbulence noise source in low flow have not been revealed yet. So, we reveal the turbulence noise source in low flow in this paper. First of all, when we measure time-base waveform of the noise and analyze frequency characteristics of that in low flow, we know blade passing frequency noise and turbulence noise have a big influence on the noise in low flow. So, we think that the turbulence noise in low flow is caused by the influence of blade passing, and then we measure velocity turbulence at blade following edge. As a result, we understand that the turbulence at blade following edge is the largest in low flow. From the above, we reveal that the turbulence at blade following edge is the turbulence noise source in low flow.
