Pressure limit in the recirculation zone

Hìr0 · April 4, 2011, 16:58

Hi,
I try to simulate a combustion chamber with a step upstream of the injector. The air enters the combustion at M=2.79, T=1200K, and p=101325Pa; I initialized all domain with the inlet condition of the air flow and chemistry is off. Near the step the air is subjected to a strong expansion and a recirculation zone occurs, there pressure goes down as the temperature (<0) and this causes out of temperature range error. How can I solve this problem? I'm trying a fourth order for grad(p) but I don't think it will be useful. What about time step and Courant No.? if I set a low under relaxation factor for p? I use a fixed deltat=1e-9 and MaxCo =0.01.

Thank in advance!

Hìr0 · April 5, 2011, 08:56

Anyone can help me? Maybe the problem is the initial condition of internalField in U.file (1204m/s):

..............===================== H2(30°) =============
..............|| vacuum / ->
..............|| zone / ->
========
->
->
->
==================================================

if I initialize the field with U=0 I obtain a strong expansion of H2 (pH2=200000Pa vs pair=101000) => TH2 already low (T=133K) goes down=> janaf error. Any suggestions?

April 4, 2011, 16:58	Pressure limit in the recirculation zone	#1
Hìr0 New Member Luigi Join Date: Apr 2011 Posts: 10 Rep Power: 15	Hi, I try to simulate a combustion chamber with a step upstream of the injector. The air enters the combustion at M=2.79, T=1200K, and p=101325Pa; I initialized all domain with the inlet condition of the air flow and chemistry is off. Near the step the air is subjected to a strong expansion and a recirculation zone occurs, there pressure goes down as the temperature (<0) and this causes out of temperature range error. How can I solve this problem? I'm trying a fourth order for grad(p) but I don't think it will be useful. What about time step and Courant No.? if I set a low under relaxation factor for p? I use a fixed deltat=1e-9 and MaxCo =0.01. Thank in advance!

April 5, 2011, 08:56		#2
Hìr0 New Member Luigi Join Date: Apr 2011 Posts: 10 Rep Power: 15	Anyone can help me? Maybe the problem is the initial condition of internalField in U.file (1204m/s): ..............===================== H2(30°) ============= ..............\|\| vacuum / -> ..............\|\| zone / -> ======== -> -> -> ================================================== if I initialize the field with U=0 I obtain a strong expansion of H2 (pH2=200000Pa vs pair=101000) => TH2 already low (T=133K) goes down=> janaf error. Any suggestions? Last edited by Hìr0; April 5, 2011 at 09:32.

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