Assignment 11

PART 1:- Single cyl DI add case 2 with discretization length 0.1 mm for intake runner and compare with default case 1

AIM:- To determine parameter such as torque, BSFC, max cylinder pressure and simulation time.

MODEL:-

CASE SETUP:-

ENGINE PERFORMANCE PREDICTION:-

KEY CYLINDER PREDICTIONS:-

RUN TIME SUMMARY:-

• For case 1 computational time = 0.3415 min = 20.49 sec
• For case 2 computational time = 234.97412 min = 3 hrs 55 mins
• Therefore case is almost 234.97/0.34 = 691 times slower than case 1.

RESULT:-

Parameter	Case 1	Case 2
Torque [Nm]	96.2	95.9
BSFC [g/kWh]	238.2	238.9
Max Cylinder Pressure [bar]	117.11	115.18
Simulation time [min]	0.3415	234.97

CONCLUSION:-

• Reducing the discretization length from 40 to 0.1 mm has not affected the result, that much but the computation time has increased drastically.

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

STEP 1:- Create and import file

STEP 2:- Separating section by curve

From the import model we can see that the end and the inlet are closed. We need to remove these caps so the end are open and avaliable for flow. To do this use separate by curve option. This will also separte the intake runner into two different section near the area change.

The tolerance control how sensitive this operation is to change in the surface area of the part as shown in above figure. Keep tolerance of 1 mm is used in this case.

Delete the end section of the runner and plenum as shown in below figure.

STEP 3:- Using the Cutting Plane

To do this go to convert tab --> Cutting plane group --> 3 point cutting plane and select 2 point on the underside of the manifold block. Translate the plane by dragging the left click on the plane, such that only runner are cut and not the manifold. Select the manifold with left click and click on clip to separate the runner from the manifold.

STEP 4:- Converting section into flow component

In this step, we convert the different section into flow component. Start with first section of the first runner. Right click on the runner and click convert shape to component.

Select multiple bends since it has more than one bend in different planes. Since, we made the cut near the manifold where there is smooth transition into the runner, the diameter at the end of the pipe is not really appropriate. Therefore, it is necessary to choose which diameter to use for this cross section.

Keep the wall thickness as 1 mm, Pressure as 1 bar, Temperature 300 K and mixture as air.

Repeat the procedure and convert the first section next to the manifold of the other 3 runner into flow component.

Similarly, it is necessary to convert the end section of each runner into component.

Delete the extra surface created by the separate by curve.

STEP 5:- Adding a custom connection

In converting the runner the information regarding the curved entry from the manifold fillet are lost. This curved entry would represent a better flow transition than a default orific connection, so we need to manually add an orific connection to represent this.

Setting as parameter

STEP 6:- Adding a subassembly connection impose connection direction

In this step we specify the end boundary connection to the runner.

STEP 7:- Dividing Pipe Section with area change

On the other end of the manifold, the entrance appear to consist of a pipe section with a round and D shape, then a 90 degree turn into the manifold. The strainght section can be converted into 2 pipes, one representing each effective diameter.

Now, we have to separte the D shaped pipe section from the flow split entering the manifold.

Next convert the rounded pipe shaped section and specify a subassembly connection on the last pipe since it has an end boundary.

STEP 8:- Seperate the manifold from the 90 degree entrance flow split

In this step, we have to separate the manifold from the 90 degree entrance flow split.

STEP 9:- Converting Section into General Flowsplit

In this step, convert the entrance to the manifold into a flow component.

STEP 10:- Dividing a large volume into smaller

In this, we will divide the entire manifold into 3 section, a centre section and two end section. The first step is to use a cutting plane to cutt off the first end section toward the first runners.

Once, the plane is formed we only have to translate the plane such that it is between the 1st and 2nd runner shown in the above image.

STEP 11:- Restoring a cutting plane

We need to make one more cut between the 3rd and 4 th runner to finish dividing during the manifold

STEP 12:- Determining orientation during conversion

In this step we convert the all the section of intake manifold in flow split

STEP 13:- Adding flow connection

During this process of converting mesh to component, we created several pipe which do not allign perfectly. To remedy this, we can use the flow connection operation to join the runner section at the top of the manifold.

STEP 14:- Discretizing the Model

To describe the model go to Home --> Under Model Expert Group --> Click Export GT model