# Simulating a Vacuum Pump

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

 August 11, 2011, 18:06 Simulating a Vacuum Pump #1 New Member   Marisa Join Date: Sep 2010 Posts: 3 Rep Power: 9 I would like to simulate the flow in a chamber that is being pumped on by a scroll pump. The pressure inside the chamber is supposed to stay a constant 0.3 atm, the gas that is sucked out by the pump is being replace through inlets. Currently I am using stagnation inlets set to -0.7 atm and a pressure outlet set to -0.9999 atm (reference pressure 1 atm). Is this the most correct way to do this simulation?

 August 15, 2011, 01:04 #2 Senior Member   Ping Join Date: Mar 2009 Posts: 321 Rep Power: 12 several suggestions: - since the pressures everywhere are going to be around .3atm absolute, set the reference pressure to that value - will aid convergence - then outlet will be 0atm relative to your new reference pressure (assuming this is what you really want) - not sure about your stag.inlet since you need to know the stagnation conditions - you might not have compressible flow, so it is easier, otherwise need total pressure, total temperature - see Help topic Modeling Physics > Setting Up Physics > Setting Types > Boundary Types Reference > Stagnation Inlet

 October 19, 2016, 10:35 #3 Member   James Willie Join Date: Mar 2009 Posts: 80 Rep Power: 10 Hi Marisa, I was wondering if you found a solution to your problem then? I am modeling a similar flow for a vacuum pump and i am using CFX as the solver and the inet is set to 'Opening' and i have given the gauge pressure there which is negative and the outlet is also set to 'Opening' and the gauge pressure there is about 6mbar. I am using Ideal gas and the flow is compressible due to tiny gaps we have inside the pump housing. In your case did it mean that your mass flow at the inet was negative and that at the outlet was positive? What about your velocity vectors? I am doing unsteady with the immersed solid method in CFX to include the rotation of the solid rotors inside the pump housing. But when i plot my velocity vectors i see the direction towards the inlet predominantly. Is this normal? Thanks! Jimmy

 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 Brinx OpenFOAM 1 April 18, 2013 04:22 enr_venkat CFX 5 November 20, 2012 12:50 Alasdair Main CFD Forum 3 March 3, 2011 01:00 leeportnoff CFX 3 December 19, 2010 17:21 Rage CFX 0 July 25, 2003 16:15

All times are GMT -4. The time now is 02:09.