Learning Forum

[Arturas Gulevskis]

Hello Team, 

I run, listed below, Chapter 5: Port-Injected Spark Ignition Engine simulation on Ansys Forte and I replicated them on GT-Suite.

• 1500 RPM w/ Spark Ignition at 688 degrees
• 3000 RPM w/ Spark Ignition at 688 degrees
• 4500 RPM w/ Spark Ignition at 688 degrees
• 6000 RPM w/ Spark Ignition at 688 degrees
• 7500 RPM w/ Spark Ignition at 688 degrees
• 7500 RPM w/ Spark Ignition at 684 degrees
• 7500 RPM w/ Spark Ignition at 680 degrees
• 7500 RPM w/ Spark Ignition at 676 degrees
• 7500 RPM w/ Spark Ignition at 672 degrees
• 7500 RPM w/ Spark Ignition at 668 degrees

The results unfortunately don't match. Forte is showing that at 7500 RPM w/ Spark Ignition at 688 degrees has the peak pressure point below 6000 RPM whereas the GT-Suite is showing it would be below 3000 RPM. The geometry and thermal inputs are the same. Valve timing is the same. Fuel compositions is the same. I am currently experimenting with intake and exhaust valve discharge coefficients. This is different between 3D and 1D simulations when it comes to set up. 

1) Can you confirm that Forte will give me realistic results if I modify the RPM and Ignition Timing in tutorial 5? Has this been done by Ansys team to validate the accuracy of the model? 
2) How can I obtain or maybe you can provide Intake and Exhaust Valve Discharge Coefficients?
3) Is Mass Flow vs Valve Lift for Intake and Exhaust for tutorial 5 available?

Please help. I'm under pressure to decide what my next move should be. 

Thank you so much. 

Kind Regards,
Arturas Gulevskis

[Ren]

Hello, 

The purpose of the tutorial is to demonstrate the steps required to model such problems and not for produciton runs. It's most likely that a finer mesh is necessary for more realistic simulations. For example, the Forte best practices guide provides advice on mesh refinement controls.

For 3D simulations the mass flow rates through the valves and discharge coefficients are not part of the user input but part of the simulation results.