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Problems modeling subsonic engine air inlet with flow separation |
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March 27, 2009, 17:42 |
Problems modeling subsonic engine air inlet with flow separation
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#1 |
New Member
Join Date: Mar 2009
Posts: 14
Rep Power: 17 |
Hi,
I need to model an air inlet for an air breathing engine (RBCC engine). Flow velocities through the duct are subsonic (Mach 0.2 - 0.5). The average static pressure at the outflow plane of the air inlet is fixed. I am having convergence problems in the regions of flow separation and I was wondering if anyone has any suggestions on how to improve convergence. I have tried increasing mesh density in the regions of separated flow but so far this has not helped. (I am also reaching the memory limits of the computers I have access to.) I have been hesitant to extend the domain past the true outflow plane since I need to achieve a given average pressure at this plane. Is it typical to extend the domain past the true outflow plane for simulations? If so, how does one achieve the desired pressure at the true outflow plane location? (iteration?). The simulation details are as follows. Domain Settings Steady state Using SST turbulence model, Ideal Gas, Total Energy model Boundary conditions - subsonic velocity inlet - opening pressure outlet. Using the entrain setting since I expect there to be regions of separated flow crossing the outflow plane. I have been hesitant to extend the domain past the true outflow plane since I need to achieve a given average pressure at this plane. Solver Settings Advection scheme: High Resolution (when using UW scheme, the simulation converges) Timescale control: Local Time scale Any suggestions would be greatly appreciated! Thanks |
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March 29, 2009, 18:52 |
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#2 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,862
Rep Power: 144 |
Have a look at:
http://www.cfd-online.com/Wiki/Ansys...gence_criteria Try the recommendations on that page but I bet in your case you have transient flow structures so you will need to run a transient simulation. Glenn Horrocks |
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March 29, 2009, 19:42 |
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#3 |
New Member
Join Date: Mar 2009
Posts: 14
Rep Power: 17 |
Thanks Glenn,
I'll give the transient simulations a try. |
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