[cheet]

Hello,
I am simulating combustion processes of heptane/octane inside a rapid compression machine (batch compression, pressure driven, no valves, no spark). I am using ccm+ for geometry, ice for trimming (sector model) and combustion setup and prostar for solver setup and postprocessing. I am currently facing two issues:

1) I can observe combustion only by using the ECFM-3D model. The compression stroke is ok (deviation ~10% to experiments) but the extra pressure generated by combustion is way too high (experiment: +5bar, simulation: ~+100bar). Timescale is set adequately. There may be an issue with the state of premixing, as we do not exactly know about that inside our machine. If I use the PVM-MF model (mixed, non-prem., hcci), I cannot observe combustion at all, even if I set harsher boundary conditions.

2) Regardless of my settings, the temperature residues are very large. Close to lower dead point, they start accumulating (~0.002) and grow up to a value of 30 .. 500 at upper dead point.

Thanks in advance for your support.
Greets, Bernhard