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#329 - 05/02/01 07:27 AM high pressure piping vibrations due to plunger pumps pressure pulsation
rvsojitra Offline
Member

Registered: 05/02/01
Posts: 1
Loc: Vadodara, Gujarat, India
I want to analysis high pressure urea plunger pump piping system for pulsation induced vibrations? Vibrations are in the range of 300 to 750 micron at different locations in the piping system. Piping is having design pressure of 250 Bar. How Caesar - II will help me in such analysis

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#330 - 05/02/01 10:21 AM Re: high pressure piping vibrations due to plunger pumps pressure pulsation
Richard Ay Offline
Member

Registered: 12/13/99
Posts: 6013
Loc: Houston, Texas, USA
The first thing to do is to determine the cause of the vibration. Is it caused by:
1) acoustics, flow in the pipe
2) pulsation, pressure fluctuations across elbow-elbow pairs
3) mechanically induced, pump vibration at the nozzle

Items 1 and 2 are solved in a "similar" fashion, by guessing an applied force magnitude, and then scaling the force based on measured response. For acoustics, the direction of the force is usually perpendicular to flow direction, while pulsation is axial.

A <em>"uniform pulsation"</em> problem can be evaluated in CAESAR II using the Harmonic Solution method. A step by step procedure for this has been outlined in a previous post - see http://www.coade.com/ubb/Forum1/HTML/000092.html .

Note, the vibration magnitudes that you have measured are what you want to use to scale the driving force you specify.

Item 3 can be solved by measuring the pump nozzle displacement and frequency, and using these values as the load input.

In every case, the percent critical damping can be used to tweak the response.


Note, this is perhaps the most <em>uncomfortable</em> analysis (for engineers) that can be performed by CAESAR II, since you have to guess at magnitudes and directions to <em>simulate</em> the loading on the real system.

------------------
Regards,
Richard Ay (COADE, Inc.)
_________________________
Regards,
Richard Ay

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