# Modelling an intake system

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

 November 4, 2009, 06:25 Modelling an intake system #1 New Member   Susan Join Date: Oct 2009 Posts: 23 Rep Power: 9 Dear All, I need to model a kind of an air intake system. I have a common duct where the air is sucked from ambient and at the other end is the duct divided into two smaller ducts. In the two smaller ducts there is a suction fan installed in each duct. A system like a “Y” I know the desired mass flow through the system. What kind of boundaries should I use, especially for the outlet (where the fans are). Would it be correct to use an inlet vent, where the air is sucked from ambient Exhaust fan at the outlet of the two small ducts and then use a constant pressure jump. And adjusting the pressure jump until the desired mass flow is obtained. The duct is not a symmetric “Y” so I would expect an uneven mass flow in the two “legs”, can I predict that if I use the pressure jump at the outlet Thanks in advance S

 November 4, 2009, 07:14 #2 Member   Bram Join Date: Apr 2009 Location: Belgium Posts: 81 Rep Power: 9 If your flow is incompressible <0.3mach use velocity boundaries at the fan side. You can solve this different ways, easiest would be to blow the air through your system instead of suction at two locations. Just use a velocity in at your orifice and see the flow distribution at the outlet sides. This should give you a good idea on how to dimension your 2 fans

 November 5, 2009, 05:10 #3 New Member   Susan Join Date: Oct 2009 Posts: 23 Rep Power: 9 Thanks for your reply. Just before the fan (in real world) then must the flow see a pressure rise through the fan, how do I get the effect into the calculation if I don't use the exhaust fan outlet boundary S

 November 5, 2009, 07:26 #4 Member   Bram Join Date: Apr 2009 Location: Belgium Posts: 81 Rep Power: 9 I need you to be more precise about your geometry, are the fans located inside the duct and is the duct continuing before and after the fan? Also make sure to extend your boundaries for better convergence. What is your actual goal of this CFD? to see the flow pattern? If only you need to dimension the fans i would use other tools. If your goal is flowrate X through orifice in then I would take a calculator, find the ratio of the 2 areas of branch 1 and 2 and from this get the flow rate distribution with respecty to total flow rate. NO CFD required.

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Mohan CFX 20 March 30, 2011 18:56 LIUYIN CD-adapco 8 November 18, 2007 21:03 Piyush FLUENT 1 May 18, 2006 05:36 Riaan FLUENT 4 September 13, 2005 10:23 reza besharati Main CFD Forum 4 June 4, 2001 20:23

All times are GMT -4. The time now is 19:35.