Speed-dependent characteristics of centrifugal fan noise are discussed by introducing a model of wave transmission through the impeller and the inlet duct. The fan noise data at the inlet are categorized as source strength terms and a frequency-response term expressing attenuation in the propagation passage. By setting the exponent in a power-law relationship of the 2nd power of sound pressure level versus frequency at 6, i.e., a dipole source, two factors describing the source level are determined with simple relationships to the cut off clearance. The frequency response is satisfactorily predicted by introducing a one-dimensional linear wave model in which the key passage is the blade-to-blade passage selectively determined by the noise wavelength.
|Number of pages||11|
|Journal||JSME International Journal, Series B: Fluids and Thermal Engineering|
|Publication status||Published - 1989 May 1|
ASJC Scopus subject areas
- Mechanical Engineering
- Physical and Theoretical Chemistry
- Fluid Flow and Transfer Processes