Learning Forum

[Pavol Tarbajovský]

Hello,

I am getting an error about spark ignition. The spark is located inside the chamber where it should be but still throws a spark plug error. Could you please help me? In the picture, you can see where physically the spark plug is located. I really appreciate your help.

Thank you very much.

[Pavol Tarbajovský]

Hello, does somebody know how to fix that error ? I would really appreciate help since it is important for my thesis. Thank you in advance.

[Ren]

Hello, Pavol,

Please check the setting for the spark Location input under Spark Ignition->Spark task page. Make sure the spark location is correct.

 

[Pavol Tarbajovský]

Location of spark should be set insede the sub-chamber. The spehere, which represents the sprak is also shown in the area where it should be. Can be this error linked with somethink else?

[Ren]

Assuming the location of the spark location has been double-checked, this error that complains the spark location not being inside a cylinder/sub-chamber region must be caused by incorrect region IDs in the mesh. What typically happens is that the cylinder/sub-chamber region containing the spark plug is not given the correct region ID and initial conditions due to some topology issues in the surface mesh. The valves not being tightly seated is the most frequently encountered cause for such an error. To confirm, you can do a test run by turning off the spark ignition model and selecting region ID as a spatially-resolved output variable. Turning off the spark ignition model will allow this error message to be bypassed and hence allow the initial spatially-resolved solution to be saved. You can then check the region IDs and initial conditions in the initial solution using Ensight. If the valves indeed contain non-trivial gaps in the surface mesh, you can use the "Check Valves" utility within the "Utility" ribbon group to seat the valves to a specified tolerance. 

[Pavol Tarbajovský]

I checked the ensight and IDs of parts are as shown in the picture. 

The valve seat have the same proximity as shown in the picture.

[Pavol Tarbajovský]

And when I turn off spark ignition, I get this. 

[Ren]

The previous idea is to check if there are three separagte regions: intake port, cylinder chamber, exhaust port. In EnSight, you can verify it by displaying only the "Symmetry" part and color it by Region ID.

In addition, you can also visually check the mesh to see if there are any gaps between the valves and the valve seats.

 

[Pavol Tarbajovský]

I sorted out the spark plug error. The intake valve was not seated right (geometry problem). After I fixed it, it started to calculate the solution, but at around 394 degrees it failed due to timesteps being to small. How should I set time steps? 

[Ren]

This is commonly caused by some issues in the geometry such that the local velocity becomes very large resulting in the need for exessively small time steps. Please examine the solution and mesh just before the crash to see if you can find anything.