Challenge

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

Aim:

Discretization of 3D intake manifold using GEM-3D

Objective:

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

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

Part 1

Part 2

Importing the plenum .stl file to GEM 3D

Removal of caps using a selection of curves

The inlets and ends of the 4 intake runners are closed, so these caps are necessary to open for availability to flow.
Select the separate by curve option, to separate geometry by parts based on the surface of the object.
Set tolerance limit to 1
The end section of the runner and plenum is separated from the main shape, we can delete them from the model.

Separation of runner from the manifold

From the convert tab, select the 3-point cutting plane.
A cutting plane is created by clicking on three-point on the model to define a plane.
Once the plane is created, translate the plane so that it separates the runner and manifold.

Converting runner to flow component

Now we convert the shape to components by right-clicking on it.
Select the geometry type we would like to convert. Select pipe in case of the runner.
Assign port number.
Keep an appropriate dimension of the pipe and keep it fixed till the end of the pipe.
Repeat it for other runner ports.

Adding orifice connection:

To add a custom orifice, right-click choose orifice connection, and provide ID no.
Give a forward discharge coefficient of 0.95.

Adding subassembly connection to flow direction:

Select port 2 to runner end and set ID no 1. Set the flow direction to the outlet.
This helps GEM 3D to determine the direction from any specified values.
Repeat the procedure for other runners.

Divide manifold intake pipe and convert to flow:

The entrance appears as a pipe section with a round and D shape, then a 90 deg bend. The straight section can be converted into a pipe.
Select the cutting plane from the convert tab, and choose pipe normal cutting.
To separate the D section from the flow split section, we drag the cutting plane till it reaches the end it joins the manifold.
The plane can be translated as far as there is no abrupt change in dimension.
Now we provide the connection to the end pipe, by right-clicking on it, selecting add connection, selecting port ID 1 set the flow direction as the inlet.

Separating 90 deg flow split from the manifold

Converting manifold into smaller section and converting to flow components

Adding flow connection

To align the pipe properly we add a flow connection
To join the runner click on the flow connection face at the end of the first runner, then click at the intake of the second runner.

Discretized the model

Conclusions:

The average run time for case 1 is 1.3 sec and for case 2 is 1145 sec.
The factor of real-time for case 2 has increased to 14450 which is very high.
Negligible changes in values can be observed such as BP, BT, BSFC max pressure, and max temperature.
Since no significant changes are found so the intake discretization length should be 0.44 times bore and for exhaust, it is 0.55 times the bore.

Ship work like this
in your own course.