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

measured pressure in the discharge pipe jumps

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

LinkBack Thread Tools Search this Thread Display Modes
Old   October 30, 2006, 02:23
Default measured pressure in the discharge pipe jumps
Posts: n/a
I have a tank filled with some liquid for experimental purpose. I am emptying the tank from the bottom and in this bottom pipe measuring the pressure at the center point of the pipe. When the valve is close, I measure the static pressure at the point of pressure sensor. Now, I open the valve full. Due to the nature of the experiment, I have a high velocity in the flow, about 850 l/min. Now the pressure measured by the sensor also includes the kinetic force of the liquid coming from the velocity. But the pressure measured at this point is less than the pressure measured when the valve was fully closed. The tank is fast getting emptied and with time the pressure measured in the middle of the pipe is decreasing. Till now I understand why the pressure is decreasing.

After the pressure reaches a low value, I partly (about 70%) closed the discharge valve thereby reducing the flow rate to about 250 l/min. At this point, the pressure measured jumps up and then goes down again as the tank is getting emptied. I repeated this whole emptying process again by fully opening and partly closing the discharge valve, everytime I close the discharge valve partly, the pressure measured at the center of the discharge pipe makes a jump. I dont understand this jump. When I reduce the flow rate, the kinetic forces are low whereas the static forces are the same, therefore I assume it should not jump up but jump down. Can anyone clearify this ? Did anyone witnessed similar behaviour?

Thanks in advance.

  Reply With Quote

Old   October 30, 2006, 07:54
Default Re: measured pressure in the discharge pipe jumps
Posts: n/a
Can you describe the detail of your pressure-measuring instruments please?

Pitot tube, transducer, ???

How is/are the sensor/sensors oriented relative to the flow? Facing upward, sideways, both, neither?

  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
total pressure change in a pipe flow Im FLUENT 5 February 23, 2017 08:55
My Revised "Time Vs Energy" Article For Review Abhi Main CFD Forum 2 July 9, 2002 09:08
Terrible Mistake In Fluid Dynamics History Abhi Main CFD Forum 12 July 8, 2002 09:11
fluid flow fundas ram Main CFD Forum 5 June 17, 2000 21:31
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 18:42.