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About the utilization of the Combustion Fitting Tool


Hi, everyone. I am using the IFP library to simulate an engine. I've run some simulations in different RPM cases. When i tried to use the Combustion Fitting tool to adjust the simulation results to the Experimental data, the comparison seemed  a little weird. Usually the comparison is presented in one cycle(0 to 720 degree), but my result just gave me a little portion of the in-cylinder pressure shape. Can someone tells me which setting should i change in order to get the whole shape in one cycle? Thank you (figure 1 is the normal one, figure 2 is my result)








Re: About the utilization of the Combustion Fitting Tool

Siemens Valued Contributor Siemens Valued Contributor
Siemens Valued Contributor


You are probably using the tool with the CFM combustion chamber. On the 4th step (parameters), you have to fine tune compression, then combustion and then exhaust parameters.

4th step window4th step windowAs you can see on this figure, you can select compression, combustion and exhaust tab. Regarding the tab selected, we will compute the cycle from the Intake Valve Closure (IVC) to the Spark Advance (SA) for the compression fitting and then for the combustion and exhaust, we will compute the all cycle from IVC to the Exhaust Valve Opening (EVO).


From your figure, we can see that you are visualizing only the compression stroke. Switch to the combustion tab and you will have the all cycle.


Also, it seems that your compression ratio or cylinder geometry is not matching your experimental pressure curve. During the compression stroke, where no combustion phenomenon take place, only the piston moving up to compress air, increases the cylinder pressure. So if your geometry is correct, you should not have such errors on the simulated pressure curve.