Vibrations due to pressure drop over orifice

[S4in]

Hello everybody!
Do any of you have any tips on how to calculate vibrations caused by pressuredrop over an orifice?
It now seems that higher backpressure leads to heavier vibrations.
The flow is also fluctuating, reprociating pump.

Any tips on litterature would also be welcome!

Cheers,
Sai

 

[monkeydog]

Try asking this question in the fluid power or piping group. Sounds like "flow induced vibration".

 

[Warpspeed]

It sounds to me like "vortex shedding".

This is an unstable oscillatory flow condition set up when flow is interrupted by a blunt unstreamlined body in the flow path. It is what causes flags to wave or flutter in a breeze.

The faster the flow, the higher the frequency created in the wake. Some commercial fluid flow meters operate on this principle.

http://en.wikipedia.org/wiki/Vortex_shedding

 

[roydm]

Sounds more like cavitation to me due to the water boiling off. If it sounds like gravel passing that's what it is for sure. It shouldn't do much harm in that situation as it will probably be mid pipe where it collapses back.
A trick you see sometimes is to add a small amount of air after the plate.
An orifice program should be able to calculate the noise (vibration) for you.

Roy

 

[S4in]

Thank you!
Do you have any good orifice programs to recommend Roy?

Br,
Sai

 

[roydm]

Sai,
I just had a look at one suggested by Mark Hill. It looks OK
Click on the blue button "Start Calculator"

http://www.flowmeterdirectory.com/flowmeter_orifice_calc.html

Faiing that most instrument suppliers have one for free e.g. Emmerson

Good Luck

Roy

 

[S4in]

Ah, just what I needed
Gonna check it out now!

Br,
Sai