Experimental and computational investigation of the effect of blade sweep on acoustic characteristics of axial fan

Abstract

The swept blade is one of the most efficient and practical techniques to alleviate the noise radiated from rotating fans. In this study, the swept effects of an automotive cooling fan on its acoustic characteristics were investigated using numerical and experimental approaches. Straight, forward, and backward-swept blades with a serrated shroud configuration were fabricated for the automotive cooling systems, and their performance and noise levels were measured. Moreover, measurements on the acoustic spectra were used to validate the numerical predictions. The pressure fluctuation on the cooling fan system, including the fan and shroud, was calculated from unsteady computational fluid dynamics simulation, and the acoustic signal at observer positions was predicted using an acoustic analogy. The swept effects in terms of noise reduction were compared for all three swept blades. Results indicate that the sweep angle in the forward direction can reduce the noise level of the cooling fan with a serrated shroud. Hence, the characteristics of the noise source caused by swept blades surrounding the shroud were identified in automotive cooling fans. Our findings in the present study provided significant insight into the acoustic characteristics depending on the direction of the swept blade, they can be used as a guide for designing a low-noise fan blade. (c) 2021 Elsevier Ltd. All rights reserved.