CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > CONVERGE

Spray Calculator

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

Like Tree2Likes
  • 1 Post By tmburton
  • 1 Post By tmburton

Reply
 
LinkBack Thread Tools Display Modes
Old   November 5, 2017, 12:08
Default Spray Calculator
  #1
New Member
 
Hamed
Join Date: May 2017
Posts: 16
Rep Power: 3
hamedc is on a distinguished road
Hi,

I've entered the shape values from the laboratory injector data that was tested with the Bosch test.
I've imported this values by scaling only the positive values of ROI(g/s) with the desired duration(ms), into the shape rate profile.
I also have considered a dwell time between two injection timing.
In contrast to the main injector pressure, more pressure is obtained (or Cd) using spray calculator.
My main question is how to obtain the shape values from the ROI(g/s) data?

Thank you in advance
Regards,
hamedc is offline   Reply With Quote

Old   November 8, 2017, 12:30
Default
  #2
Member
 
tmburton's Avatar
 
Tristan Burton
Join Date: Sep 2017
Posts: 79
Rep Power: 2
tmburton is on a distinguished road
Hamed,

The rate shape you enter in CONVERGE Studio during spray setup is just a way of prescribing the shape of the mass flow rate vs. time profile for your injection event. CONVERGE will shift the x-axis (time or CA) to begin at inject_start_time, scale the x-axis (time or CA) to fit into your specified inject_duration, and scale the y-axis (mass flow rate or velocity) to achieve the required inject_mass.

Best regards,

Tristan
__________________
Tristan Burton
Senior Principal Engineer
CONVERGECFD
tmburton is offline   Reply With Quote

Old   November 24, 2017, 04:09
Default
  #3
New Member
 
Hamed
Join Date: May 2017
Posts: 16
Rep Power: 3
hamedc is on a distinguished road
Quote:
Originally Posted by tmburton View Post
Hamed,

The rate shape you enter in CONVERGE Studio during spray setup is just a way of prescribing the shape of the mass flow rate vs. time profile for your injection event. CONVERGE will shift the x-axis (time or CA) to begin at inject_start_time, scale the x-axis (time or CA) to fit into your specified inject_duration, and scale the y-axis (mass flow rate or velocity) to achieve the required inject_mass.

Best regards,

Tristan
Thank you for your reply.

I have an injector that injects the iso-octane in two stages and at a pressure of 1000 bar.
I used a trapezoidal profile as rate shape and set the axis. however, the spray calculator determined over-predicted value for injection pressure.

I have attached these rate values.

Best regards,
Hamed
Attached Files
File Type: xlsx ROI.xlsx (9.5 KB, 4 views)
hamedc is offline   Reply With Quote

Old   December 6, 2017, 16:25
Default
  #4
Member
 
tmburton's Avatar
 
Tristan Burton
Join Date: Sep 2017
Posts: 79
Rep Power: 2
tmburton is on a distinguished road
Hamed,

Is your engine speed 1250 RPM? When I plug this into the spray rate calculator with your rate shape, I get peak pressures around 890 bar.

Best regards,

Tristan
__________________
Tristan Burton
Senior Principal Engineer
CONVERGECFD
tmburton is offline   Reply With Quote

Old   December 6, 2017, 17:07
Default
  #5
New Member
 
Hamed
Join Date: May 2017
Posts: 16
Rep Power: 3
hamedc is on a distinguished road
Quote:
Originally Posted by tmburton View Post
Hamed,

Is your engine speed 1250 RPM? When I plug this into the spray rate calculator with your rate shape, I get peak pressures around 890 bar.

Best regards,

Tristan
My engine speed is 1300 RPM.
Are the rate values I entered wrong?

Best regards,
Hamed
hamedc is offline   Reply With Quote

Old   December 6, 2017, 18:41
Default
  #6
Member
 
tmburton's Avatar
 
Tristan Burton
Join Date: Sep 2017
Posts: 79
Rep Power: 2
tmburton is on a distinguished road
Hamed,

I plugged your rate shape into our PFI example case and used the spray rate calculator as a quick check (see attached). Our example case has 4 nozzles each of 250 micron diameter. Your injector may be different.

Best regards,

Tristan
Attached Images
File Type: jpg SprayRateCalculator.jpg (88.2 KB, 7 views)
hamedc likes this.
__________________
Tristan Burton
Senior Principal Engineer
CONVERGECFD
tmburton is offline   Reply With Quote

Old   December 8, 2017, 10:36
Default
  #7
New Member
 
Hamed
Join Date: May 2017
Posts: 16
Rep Power: 3
hamedc is on a distinguished road
Quote:
Originally Posted by tmburton View Post
Hamed,

I plugged your rate shape into our PFI example case and used the spray rate calculator as a quick check (see attached). Our example case has 4 nozzles each of 250 micron diameter. Your injector may be different.

Best regards,

Tristan
My injector has 7 nozzles each of 141 micron diameter
Thank you for your response

Best regards,
Hamed
hamedc is offline   Reply With Quote

Old   December 12, 2017, 18:41
Default
  #8
Member
 
tmburton's Avatar
 
Tristan Burton
Join Date: Sep 2017
Posts: 79
Rep Power: 2
tmburton is on a distinguished road
Hamed,

Under those conditions, I see peak pressures of 2085 bar for C_D=0.8, and 1334 bar for C_D=1.0. If these values are too high then you should check your injection duration, injected mass, and nozzle diameter values.

Best regards,

Tristan
hamedc likes this.
__________________
Tristan Burton
Senior Principal Engineer
CONVERGECFD
tmburton is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Can anyone suggest a good tutorial of Spray Combustion in Ansys FORTÉ? shubhra ANSYS 2 October 5, 2017 06:06
[sprayFoam] strange spray formation behaviour pbalz OpenFOAM Running, Solving & CFD 0 March 23, 2015 12:41
[ANSYS Meshing] Meshing for study on fuel spray carolann ANSYS Meshing & Geometry 0 June 25, 2012 02:59
spray injection mmacrb FLUENT 0 January 10, 2007 05:57
problems with unsteady spray simulation Mathias FLUENT 1 July 20, 2006 16:13


All times are GMT -4. The time now is 23:14.