CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > General Forums > Main CFD Forum

Nozzle for discharge modeling

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   February 23, 2016, 19:12
Default Nozzle for discharge modeling
  #1
New Member
 
Join Date: Feb 2016
Posts: 7
Rep Power: 10
prij is on a distinguished road
Hi,

I have been using this nozzle whose inlet contains supercritical CO2 and the divergent part of the nozzle is ambient air. So basically, CO2 is passing through a small hole into the atmosphere. I am using Multiphase VOF model (Phase-1 is air and Phase-2 is CO2) with pressure inlet and pressure outlet as BC's. I have set the volume fraction of CO2 as 1 in the inlet and backflow volume fraction in the outlet for CO2 as 0. When I run the simulation and generate results for volume fraction for phase-1(air) and phase-2(CO2), I still observe that the volume fraction is 1 throughout for CO2 case and 0 for air throughout with only changes at the nozzle throat. Even the reference values populated when I give inlet and outlet are not changing. I am confused whether I am using the right method and way. I would appreciate if somebody could guide me with this.

Thanks.
prij is offline   Reply With Quote

Old   May 4, 2016, 03:28
Default
  #2
Member
 
Join Date: Aug 2014
Location: Germany
Posts: 77
Rep Power: 11
harry123 is on a distinguished road
I use VOF method for simulating water jet into air. The problems I encountered for wrong volume fractions along axis for water were:

1. Using small time step when mesh was coarse.
2. Changing inlet velocity profile affected the results.
3. Changing inlet turbulence intensity affected the results.

I'm still working on it, but so far these are the issue I came across.
harry123 is offline   Reply With Quote

Old   May 4, 2016, 03:36
Default
  #3
New Member
 
Join Date: Feb 2016
Posts: 7
Rep Power: 10
prij is on a distinguished road
Hi,

Thanks for your reply.

Did you get the required momentum for your water jet when it was let out in air? Because in my case it is a gas and the dispersion of CO2 in air was not giving me sufficient momentum to disperse up to great distances. What was the turbulence intensity in your case?

Thanks.
prij is offline   Reply With Quote

Old   May 4, 2016, 04:33
Default
  #4
Member
 
Join Date: Aug 2014
Location: Germany
Posts: 77
Rep Power: 11
harry123 is on a distinguished road
The plot for variation of velocity along axis was matching (though not exactly) with benchmarks, so I guess there is no problem there.

I had used turbulent intensity of 0.01 for my simulations. Using 0.1 gave me results not matching benchmark.
harry123 is offline   Reply With Quote

Reply

Tags
discharge model, nozzle

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
How to go about modeling injection nozzle two phase flow in FLUENT? skonda2 Fluent Multiphase 0 March 17, 2015 07:52
Modeling internal and external flow for a nozzle smschnob Main CFD Forum 1 November 11, 2010 17:12
Modeling water jet exiting nozzle pluto STAR-CCM+ 1 November 18, 2009 19:41
Modeling Laval nozzle, subsonic flow to supersonic Bloshchitsyn Vladimir CFX 2 June 18, 2007 05:18
compressible flow in a counterflow nozzle d.vamsidhar FLUENT 0 November 24, 2005 01:45


All times are GMT -4. The time now is 23:34.