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Old   July 22, 2004, 06:03
Default constant volume combustion
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vaibhav nadkarni
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hi all

i've to simulate turbulent premixed combustion in a constant volume bomb(cube)& to record pressure time history

the bomb is filled with fuel-air mix & then all valves are closed the turbulence is created by moving a perforated plate inside the cube the mix is ignited at center by a spark

the problem is there is no inlet outlet so no inlet or outlet bc is there only bc is wall bc

problem is(i)can i use edm for this (ii)i,ve defined high temp on some elements in center but combustion is not taking place

please help me in urgent thanx
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Old   March 22, 2011, 17:23
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Iltesham
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Hi Vaibhav.
I am trying to do very similar simulation now. I shall be ever grateful to you if you could let me know what steps did you follow for combustion in the closed chamber? I am trying to ignite the fuel using high temperature patch but not working. Also i tried the spark model but still not working. can you please help me here. I will greatly appreciate.
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Old   March 23, 2011, 17:43
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The simulation is done by your workstation. You have to model. In other words you have to assemble equations which give you a model of the physical reality. If you use a code, which has all these things already in, you should at least check what the code does.

Without loss of generality have a look at http://www.cfd-online.com/Wiki/Combu...Break-Up_model . Do you see temperature in the chemical source term for turbulent combustion? No, it does not feel. There is also no enthalpy. That's the reason why many combustion models can not be ignited by temperature initialization or heat release.
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Old   March 26, 2011, 12:23
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Quote:
Originally Posted by joey2007 View Post
The simulation is done by your workstation. You have to model. In other words you have to assemble equations which give you a model of the physical reality. If you use a code, which has all these things already in, you should at least check what the code does.

Without loss of generality have a look at http://www.cfd-online.com/Wiki/Combu...Break-Up_model . Do you see temperature in the chemical source term for turbulent combustion? No, it does not feel. There is also no enthalpy. That's the reason why many combustion models can not be ignited by temperature initialization or heat release.
I agree to what you are saying. But i have exhausted all my options. I am just a student and this forum was the last place i thought would give some sort of guidance.
Please look at this paper,
They have done exactly what i want to do and they have used a spark to ignite the fuel in side the combustion chamber.

http://www.sciencedirect.com/science...9&searchtype=a
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Old   March 26, 2011, 16:03
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The last two years I spent more time on fan blades then on combustion. So I did not look into 13.0. I do not know if there is a new feature which solves your problem. For 12.1 the situation was as follows:

  • For EDM: there is no ignition model in ANSYS CFX available. In order to start reaction you have to bring some products in. This could be done by source term or even simpler by initialization of some product mass fraction.
  • As an alternative you may use the partially premixed model. For this model there is an ignition model available. It requires flamelet libraries, which has to be generated by CFX-RIF. RIF requires an own license. For testing purposes there are a methane and hydrogen lib available in the installation
I clicked on the link. They talk from Fluent not CFX.

Regards,
Joey

PS: Do you really expect me to pay 31,90 $ and two hours in order to understand what you intend to do?
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