Tuning HCCi combustion
 

Hello guys,

I am simulating combustion of heptane inside a rapid compression machine. It is kinda similar to HCCI.
My stroke curves match perfectly, dont take notice of the deviation after upper dead point, its a sensor error. I also added an extra volume, accounting for the pressure losses during compression. But I have some troubles simulating combustion. I wanna make the grey curve (simulation) match with the blue curve (experiment).
Current condition set: T=350K, p=3bar, walls const temp. I also tried with adiabatic walls, but that will lead to overprediction of the ignition. I am using a TKI table. Fuel mass is OK, total mass is a bit too big. Thats for a reason (im not simulating injection - which leads to cooling, but init conditions are calculated via ideal gas law, so im using EGR to reduce mass a bit). Lambda=1,75

Anyone have an idea?
https://www.pic-upload.de/view-32892...nannt.jpg.htmlhttps://www.pic-upload.de/view-32892...nannt.jpg.htmlhttps://www.pic-upload.de/view-32892795/Unbenannt.jpg.html

Greetings, cheet