[allen Duan]

I am doing simulation on hydrogen air combustion characteristics.
But i am having difficulty finding the mech.dat file for simulation in converge. Can someone suggest some credible sources to obtain such files?

[drowinsk]

Hello and thanks for your question. The hydrogen sub-mechanism of the C3 mechanism is available directly from Converge Studio, in: Chemistry tools -> C3 Mechanism -> Fuel Species: H2 (Hydrogen). To use a different mechanism, there are quite a few sources online supplying a mech.dat and therm.dat, though they are not bundled directly into Converge Studio, they can be imported through the "read file" option. Please let us know any time if you have any other questions.

Best regards,
David

[allen Duan]

Originally Posted by drowinsk

Hello and thanks for your question. The hydrogen sub-mechanism of the C3 mechanism is available directly from Converge Studio, in: Chemistry tools -> C3 Mechanism -> Fuel Species: H2 (Hydrogen). To use a different mechanism, there are quite a few sources online supplying a mech.dat and therm.dat, though they are not bundled directly into Converge Studio, they can be imported through the "read file" option. Please let us know any time if you have any other questions.

Best regards,
David

Thank you very much for your suggestion. I used your method to calculate the jet ignition combustion of hydrogen in a constant volume combustion bomb, utilizing different reaction mechanisms （mech.dat and therm.dat）. The turbulence model used was the default RNG k-ε turbulence model in CONVERGE 3.1. The results obtained with different mechanisms were essentially the same, but compared to the experimental measurements, the simulated combustion rate was significantly lower than the experimental results. Under the same conditions, the simulated combustion rate was about half of the experimental rate. Could this result be significantly related to the choice and settings of the turbulence model? Could you provide me with some advice? Thank you very much.

Best wishes,
Allen

[drowinsk]

Hi Allen, thank you for your follow-up. For this type of problem I would recommend to look at some of the possible sources of error: (1) user error / gross error: is the problem set up in the same way at the conditions you are comparing too, any difference in initial conditions, boundary conditions, material properties; (2) modeling error: do your modeled equations accurately represent the key physics of the problem you are studying, (3) numerical error: is the grid fine enough and time step fine enough to solve your modeled equations to within acceptable error. For the problem you described of turbulent jet ignition of hydrogen, I would recommend to look into the turbulence/combustion model coupling -- if applying a RANS turbulence model to a reacting flow without any additional modeling of the chemical source term, you may need to enhance the turbulent diffusivity (which can be achieved by changing the turbulent Schmidt number, or you may need to look into higher fidelity turbulence closures, for example LES with finer grid resolution to achieve a more accurate burn rate. You could also consider other combustion models (FGM and TFM) to improve the prediction of the burning rate with RANS, however from our experience detailed chemistry with LES and high resolution grid is generally the more robust modeling strategy. Feel free to let us know any time if you have any further questions.

Originally Posted by allen Duan

Thank you very much for your suggestion. I used your method to calculate the jet ignition combustion of hydrogen in a constant volume combustion bomb, utilizing different reaction mechanisms （mech.dat and therm.dat）. The turbulence model used was the default RNG k-ε turbulence model in CONVERGE 3.1. The results obtained with different mechanisms were essentially the same, but compared to the experimental measurements, the simulated combustion rate was significantly lower than the experimental results. Under the same conditions, the simulated combustion rate was about half of the experimental rate. Could this result be significantly related to the choice and settings of the turbulence model? Could you provide me with some advice? Thank you very much.

Best wishes,
Allen

[shahid76111]

Originally Posted by drowinsk

Hello and thanks for your question. The hydrogen sub-mechanism of the C3 mechanism is available directly from Converge Studio, in: Chemistry tools -> C3 Mechanism -> Fuel Species: H2 (Hydrogen). To use a different mechanism, there are quite a few sources online supplying a mech.dat and therm.dat, though they are not bundled directly into Converge Studio, they can be imported through the "read file" option. Please let us know any time if you have any other questions.

Best regards,
David

I need mech.dat file for H2+CO (Syngas) utilization in SI engine. Please guide? Thanks

[Unknown_1981]

Even I am also working on Hydrogen Combustion and even i too got same problem of Half the Combustion ,if you got your error resolved or if you got Mech.dat or Therm.dat files in other forms please guide me through solution.