unevenBLADE v2.0

App for generating uneven fan and impeller spacings for tonal and broadband noise reduction

unevenBLADE (uneven BLade Acoustic Development Engine) is a tool for generating impeller or fan configurations in which the individual blades are unevenly distributed around the circumference. By unevenly spacing the blades, there is a frequency modulation that occurs, which causes the acoustic energy from the blade passage to get distributed to other harmonics of the fundamental, which can sometimes create lower noise levels or a more pleasing tonal structure. This program uses a random spacing algorithm, as oppossed to some other methods of uneven spacing, like sinusoidal spacing.

Current Features:

• Generates upwards of thousands of different unevenly spaced fan/impeller/rotor designs for any ressonable number of blades
• All geometric configurations are statically balanced, such that the center of mass lies on the center of rotation
• Variable randomness on how chaotic the blades are spaced out
• Presents three optimized configurations: one optimized for minimized blade passage frequency, one optimized for the lowest RMS noise level, and one that balances tonal and broadband noise
• All resulting designs are realizable

Sources:

[1] B. Jiang, J. Wang, X. Yang, W.Wang, and Y. Ding, "Tonal noise reduction by unevenly spaced blades in a forward-curved-blades centrifugal fan," Applied Acoustics, vol 146, pp. 172-183, 2019.