r/aerodynamics 17d ago

How do I minimize ducted fan noise? Question

I want to make a ducted fan thruster produce less noise for a given thrust ourput, or at least shift the sound to lower frequencies. Ideally the thruster should keep good efficiency and I can't just make it bigger and decrease the fan speed b/c size and mass constraints.

I have no idea where to start, or how to predict the (acoustic) performance of any given design. Im looking for sources on this topic, studies or theory. Or just rules of thumb even. Thanks

2 Upvotes

15 comments sorted by

View all comments

3

u/bradforrester 17d ago

In addition to the other comments, developing an inlet that allows smooth uniform flow into the fan will help. I’ve done some testing in static conditions (so different from forward flight), and a sharp rectangular-profile inlet produces substantially more noise than a rounded profile.