[manu370353]

I have a well tuned reaction mechanism for a fuel and I got comparable results in zero dimensional simulation with DICI engine but when I use converge2.4 the combustion does not happen and the peak pressure is lower than the exp. peak pressure of Pressure-crank angle diagram. when I increase the initial temperature combustion happens but there is no increase in the peak pressure. What may be reason.
Manoj

[azandian]

It is hard to pinpoint the reason for this without checking out the case setup and the combustion setting. Here are some potential causes:
- The temperature and pressure in the cylinder might not be high enough to start the ignition.
- The species composition might not be set appropriately; for instance, there might not be enough fuel to start the combustion, or the fuel might not have access to sufficient oxygen.
- The initial TKE might not be large enough to sufficiently mix the fuel and the oxydizer to make it burn.
- The grid resolution might not be fine enough to correctly capture the ignition.
- Your combustion timing and/or the temperature cutoff might not be set up appropriately.

I suggest importing one of the default GDI or HSDI engine example cases (depending on the combustion model you are using) and comparing your case inputs against those settings. That might give you some clues as to what might be off in your setup.

[manu370353]

Thanks Arash Zandian but I am using a direct injection compression ignition engine sector. How can I use Compression ratio calculation.
Manoj

[SamWijey]

I invite you to attend one of our free online IC Engine training sessions. The questions you are asking are covered in detail in this class: https://convergecfd.com/events/online

[manu370353]

Hi Sameera Wijeyakulasuriya,
Thank you sure I will attend.
Regards
Manoj

[manu370353]

Hi Arash Zandian,
My fuel is biodiesel for DICI engine. Should I increase combustion temperature cut off and increase the TKE both values were taken from diesel multicomponent engine sector example. How can I make changes in combustion timing as you mentioned. Engine sector geometry is fine in my case setup. The phi_mean value comes around 1 but combustion does not happen(decrease in phi was not observed)
Regards
Manoj

[manu370353]

Originally Posted by azandian

It is hard to pinpoint the reason for this without checking out the case setup and the combustion setting. Here are some potential causes:
- The temperature and pressure in the cylinder might not be high enough to start the ignition.
- The species composition might not be set appropriately; for instance, there might not be enough fuel to start the combustion, or the fuel might not have access to sufficient oxygen.
- The initial TKE might not be large enough to sufficiently mix the fuel and the oxydizer to make it burn.
- The grid resolution might not be fine enough to correctly capture the ignition.
- Your combustion timing and/or the temperature cutoff might not be set up appropriately.

I suggest importing one of the default GDI or HSDI engine example cases (depending on the combustion model you are using) and comparing your case inputs against those settings. That might give you some clues as to what might be off in your setup.

Hi Arash Zandian,
My fuel is biodiesel for DICI engine. Should I increase combustion temperature cut off and increase the TKE both values were taken from diesel multicomponent engine sector example. How can I make changes in combustion timing as you mentioned. Engine sector geometry is fine in my case setup. The phi_mean value comes around 1 but combustion does not happen(decrease in phi was not observed)
Regards
Manoj

[azandian]

Hi Manoj,
Please email support@convergecfd.com using your official email address. We will be able to assist you better after assessing your case.