whistle noise from equipment with radial fan

[PaulLag]

HI there
Hope everybody is safe
Please, i am facing to a very puzzling problem.
I need to have a kind piece of advice concerning an ducted air conditioning equipment utilizing a radial fan.
Air flow estimated is around 8000 ft³/m
The equipment is whistling when the fan speed is low, and the whistle seems to be similar to a a G note at 400 Hz.
I have made several tests: when I open a second panel – not the ducted one – the noise wanishes.
I deem this is because I give to the air a non- obstructed way and I reduce the velocity (giving a second way out)
All hints seems to lead to a short of noise due to turbulence, or even to a kind of resonance due to air movement.

Please, has anybody of you experienced a similar event ?
Should it be the case, have you applied any solution ?
Do you know any literature reference I can refer to ?

Thanks in advance and stay safe

 

[Strong]

There can be more than one explanation. Here is a quick answer:
Search: aeolian wind noise

https://www.bing.com/search?q=aeolian+wind+noise&FORM=AWRE

Walt

 

[GregLocock]

How many blades does the fan have. What rpm does it run?

"I have made several tests: when I open a second panel – not the ducted one – the noise wanishes.
I deem this is because I give to the air a non- obstructed way and I reduce the velocity (giving a second way out)"

That's a great clue but I doubt the velocity is very important. More likely you've detuned a resonator.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[Strong]

A personal or commercial problem?

Search: air vents with whistling noise

https://www.bing.com/search?q=air+v...dd07349c584613c86252c9b74&FORM=ANAB01&PC=U531

Walt

 

[PaulLag]

Hello and many thanks to Everybody

@ Strong
a professional problem on a prototype in study.

many thanks again, stay safe