Correlation of Noise and Blade Surface Pressure in Automotive Engine-Cooling Fan

摘要

Automotive engine cooling fan is one of the major noise sources of automotive components, the most annoying feature of the noise being the discrete frequency noise at blade passing frequencies. These tonal components arc generated by blade interactions with inflow and physical configurations such as shroud and heat exchanger. Measurements of surface pressure on the rotating blade are conducted and the results are correlated with the far field sound pressure. The result confirms a strong correlation between the surface and sound pressure at blade passing frequencies. Power spectral density of the surface pressure reveals the existence of a broad hump, which is associated with broadband noise. Finally, the surface pressure data is used as input for a time domain acoustic analogy computer code called RMN-SPA and the resulting noise prediction shows very realistic agreement with the measured spectrum.