Ignition delay time simulation shows no ignition

[Howard Shaw]

    I am trying to use Cantera to validate the ignition delay time of NH3/O2/Ar mixture from literature(table 2 as in attachment).

 The problem is I cannot get results for the same fuel mixture composition in literature. It seems no ignition since the temperature keep constant.

 

 

 

[Bryan W. Weber]

Dear Howard,

1) You are using GRI-3.0 which, as far as I know, is not validated for ammonia chemistry. It was optimized for natural gas combustion. In fact, as far as I can see, they do not use GRI-3.0 in that paper at all.

2) You are only integrating for 1 ms, which may not be long enough to have an ignition. Furthermore, as best I can tell, the point you are trying to match against has an ignition delay time of 1.113 ms...

3) Why are you using a constant pressure reactor? Most shock tubes are modeled using a constant volume reactor

Best,
Bryan

P.S. It is usually not allowed by the journal for people to post a complete article on public websites, because the journal owns the copyright. Please be aware of that in the future.

[Howard Shaw]

Dear Weber,

   Thank you for your quick reply.  Your are right, I will try to modify these problem. I still have two questions. The first is that when I try to use another mechanism, in the reactor1.py there is a  "r = ct.IdealGasConstPressureReactor(gri3)" , do I need to change this gri3? Since I'm not clear about what it is.  Another question is that how to get the exact value of ignition delay time from this calculation. Because I may need to do a lot of this kind of validation, it is really important for me. Can you give me some suggestion? Thank you so much !

[Bryan W. Weber]

Dear Howard,

The gri3 in that line is the name of the variable of the Solution that is created a few lines before. If you change the left side of the equals on that line, you need to change the name in the IdealGasConstPressureReactor. Otherwise, it doesn't need to change.

You need to decide how you want to define the ignition delay. You may also need to store the values of the variables of the reactor (e.g., temperature, pressure etc) in a Python list. Then you can compute whatever you want.

Best,

Bryan

[Howard Shaw]

Dear Bryan,

  Thank you for your help. Can I ask how to also print the concentration of OH with time? I noticed that the "r.thermo.p" in the .py script gives the information of pressure, so how to also show the concentration of species like OH? thank you!

[Bryan W. Weber]

Dear Howard,

The documentation is a good place to start looking for things like that: http://cantera.github.io/docs/sphinx/html/cython/thermo.html?highlight=concentration#cantera.ThermoPhase.concentrations

Best,

Bryan