Hello!!
I have a question about piping vibration

what is the difference betweeng FIV(flow-induced vibration) and AIV(Acoutic-induced vibration)??

I'm confused about this issue.

Thank you!!

Unless your pipe is excited by someone shouting at it, the only source of acoustic energy has to be fluid flow, so I would suggest that FIV and AIV are the same.

Dear Ywson & Moverz,

FIV & AIV both are different, for your understanding to tackle any problems related to these you can refer Energy Institute Guideline methods.(2nd Edition)

For both type of vibration analysis, different Risk assessment has been explained well in detailed as said above guide.

Likelihood Of Failure (L.O.F) calculation needs to perform by considering various factors.

Regards
SND

Dear SND

If possible for you please convey me details for "Likelihood Of Failure (L.O.F)" on my personal id paresh_tulankar@rediffmail.com

Paresh

Dear SND,

Flow Induced Vibration is a low frequency vibration (typically below 50 Hz) generated by high kinetic energy Rho.V^2 and high mach number, meanwhile acoustic induced vibration is a high frequency vibration (500 hz-2000 Hz) generated by high pressure drop coincidence with high flow rate.
Physically you can see the piping system vibrate for phenomena of FIV but for phenomena AIV you will not see it vibrate physicly but you only hear a high noise generated by the high frequency. AIV also called shell mechanical vibration as the inner shell of the pipe that vibrate circumferentiall and radially.
AIV always hapened in gas system, while not for FIV, AIV can generate failure within minute (not days or weeks) but FIV can take days.

Read EI 2nd 2008 for detail LOF assessment, and visit Internoise website to get latest INTERNOISE 2012 papers related to new approach and method for evaluation AIV throug FEA and LOF or combination of both.

Regards

I agree with the distinction between flow induced vibration and acoustic vibration. We (I believe mistakenly) use the word acoustic in our dynamics course notes in itemizing different types of harmonic loads in piping systems.
CAESAR II is a beam bending program. We are calculating monents and stresses resulting from deflection off the centerline. Acoustic vibration produces high frequency response that cannot develop the deflections we expect (a tremendoous amount of energy would be required). Instead, as pointed out, acoustic response would be found in shell wall vibration. It's important, but not the realm of CAESAR II.