CFD Online Logo CFD Online URL
Home > Forums > General Forums > Main CFD Forum

Pressure drop of valve with valve opening of 30%

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Search this Thread Display Modes
Old   January 1, 2007, 11:52
Default Pressure drop of valve with valve opening of 30%
Posts: n/a

This is regarding the flow analysis of pneumatic valve of plunger type with 30% valve opening.The objective of the analysis is detemination of pressure drop for specified mass flow rate.

In this problem, following flow conditions are known.

a)atmospheric pressure at inlet b)total mass flow rate through the system

We planned to solve the problem with setting up pressure inlet and negative velocity boundary conditions at the outlet.Velocity boundary conditions at the outlet is determined from the mass flow rate and from hydraulic diameter of the outlet. whether these boundary conditions are resonable? We use fluent software for the analysis...

Since the mach number is less than 0.3, we are solving it as incompressible and also as steady state, turbuilent flow (Re>50,000)

Whether it is possible to do hand calculations for this problem? Even a ball park figure with + or -10% variation is reasonable to start with...

I don't have crane hand book to perform the equivalent length method calculations accounting the valves.

Hence, I planned to do pressure drop calculation as follows,

1) Pressure loss due to cross section change (change in shape of the cross-section is not accounted)

= density *gravity *(v^2/(2g)

2) Pressure loss due to obstructions,

Loss due to drag = Cd*0.5*density*v^2/(2g)

Where Cd- drag co-efficient

3) Pressure loss due to direction change (90 deg elbow)

= don't know how to calculate.

4) Pressure loss due to viscous friction

= Possible to calulate using head loss formula

f (L/D) * (v^2/2g)

Where f - friction factor

I would like your valuable comments about this approach.

If there are any corrections required in the computation or understanding, kindly let me know.

My intention is to know, whether the software calculated results are reasonable by comparing with the hand calculated results (Ball park figure).

Thanks for your time.

Regards, Elogesh

  Reply With Quote

Old   January 2, 2007, 12:48
Default Re: Pressure drop of valve with valve opening of 3
Posts: n/a
Elogesh, I would highly recommend that you get a copy of Handbook of Hydraulic Resistance by I.E. Idelchik. Section 9 is about pressure drop through valves. Since it has diagrams of the valves it is easier to pick out the formula that suits your conditions. The handbook is published by Hemisphere Publishing Co and is quite expensive. However, there are some old copies that were made for the old Atomic Energy Commission in 1966 (AEC-TR-6630). tOM
  Reply With Quote

Old   January 5, 2007, 12:30
Default Re: Pressure drop of valve with valve opening of 3
Posts: n/a
Dear Tom,

Thanks for the reference.

I was able to preview the book "Handbook of Hydraulic Resistance by I.E. Idelchik" through web. It looks quite good. I will just see whether our library has a copy of the book?


  Reply With Quote


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Pressure BC for combustion chamber Giuki FLUENT 1 July 19, 2011 11:35
Pressure drop match praveen.jpk FLUENT 3 September 11, 2009 03:36
cyclone pressure drop - reg Subramanian.J FLUENT 2 December 22, 2006 05:34
Pressure drop in a valve system with recirculation sacha CFX 2 March 11, 2005 05:56
Hydrostatic pressure in 2-phase flow modeling (long) DS & HB Main CFD Forum 0 January 8, 2000 15:00

All times are GMT -4. The time now is 07:26.