Week-11 : Discretization of 3D intake manifold using GEM-3D

1. Tutorial- single cyl DI add case 2 with discretization length 0.1 mm for intake runner and compare with default case 1

• • Parameters-Torque, BSFC, max cylinder pressure
  • simulation time

-> Model and Case setup

Time taken drastically increase with reduction in discretization length. For 1mm discretization length time taken was almost 40time that of 40mm discretization length. For 0.1mm discretization length time taken was almost 2680time that of 40mm discretization length. Which is a huge differance.

power and Torque shows negligible drop from 40mm to 0.1mm DL, BSFC shows 0.3% increase from 40 to 0.1mm DL, max cylinder pressure shows 1.65% drop from 40 to 0.1mm DL. There is neglegibel variation observed in key parameters yet it is clear that major variation in engine performance parameters observed from 40mm to 10mm DL. Also at same time, run time increased less than 2 times from 40mm to 10mm DL. Present situation is when model is single cylinder and simple (i.e. No turbo, No EGR, No Controllers etc.) model and discretisation only increased in intake runner. But if complications increases, instead of only Intake runner, intake port, and piping also considered for refined DL then one can assume to see more variation in results as well as more relative time differance. This some how indicates that for refined results with comparitively shorter duration one can go for DL of 0.1 times Bore insteade of 0.4 times based on case set up complication, number of cases and time in hand.

2. Explore tutorial no 2 (GEM3D) - “Building intake manifold from STL model”

First checked model into Space claim

Then open (repaired) CAD model into GEM 3D or directly open GEM 3D through SpaceClaim

Use option Split By curve to split geometry

Use Option 3 Point cutting plane to seperate manifold and connecting pipes

Plenum converted to pipe and properties defined as air

Orifice defined at junction of manifold and runner for smooth flow transition

Defined port outlets and defined ID

Piping and Flow split defined for manifold upstream connections

Manifold converted to three flow split

All the flow connections established

Final GT-ISE Model after export and re-alignment