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Author Topic: Strange resonance from DXR10  (Read 346 times)

Rob Spence

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Strange resonance from DXR10
« on: August 28, 2018, 02:13:02 pm »

Was with a client doing acoustic measurements today.
A series of loud tones & pink noise in a space to be repurposed as an exercise studio.
Did 80, 100 & 500hZ.

Config was a DXR10 sitting on a KW181.

Measurements near field for reference and then in adjacent areas of the building.

At 100 hZ the fan area of the DXR was resonating and making clicking (mechanical) sounds.

Odd.


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Chris Hindle

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Re: Strange resonance from DXR10
« Reply #1 on: August 28, 2018, 06:17:29 pm »

Was with a client doing acoustic measurements today.
A series of loud tones & pink noise in a space to be repurposed as an exercise studio.
Did 80, 100 & 500hZ.

Config was a DXR10 sitting on a KW181.

Measurements near field for reference and then in adjacent areas of the building.

At 100 hZ the fan area of the DXR was resonating and making clicking (mechanical) sounds.

Odd.


Sent from my iPad using Tapatalk Pro
I've seen/heard all kinds of resonances and odd noises from HVAC systems.
Depending on the size and shape of the ductwork, it can make a really efficient Helmholtz resonator. Add in a less-than-tight vent or frame..........
Chris.
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Stephen Kirby

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Re: Strange resonance from DXR10
« Reply #2 on: August 28, 2018, 09:11:35 pm »

Clicking sounds like something swaying into the fan blades.  Oftentimes you can't see all of the displacement of something vibrating.

If you have access to a strobe you can do what we used to in testing aircraft bit.  Sweep the strobe frequency around the input frequency (in this case the 100Hz).  It will freeze the bits at different points in their displacement and you will see the full flexing in apparent slow motion from the frequency difference.
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Re: Strange resonance from DXR10
« Reply #2 on: August 28, 2018, 09:11:35 pm »


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