•Set the Name to Exhaust Port 1

•Set the Valve function to Exhaust

•Set the Pressure to 1.1 and select bar from the drop-down menu

•Set the Temperature to 350 and select K from the drop-down menu

Figure 19-24 Two-stroke Star Controls > Initialization panel for Exhaust Port 1

•Utilize the Copy data of menu to apply the initial conditions for Region 5 to Region 6 and Region 7, as they are also exhaust ports (see Figure 19-25)

Figure 19-25 Two-stroke Star Controls > Initialization panel for remaining exhaust ports

Boundary conditions

In the Boundary conditions view of the Star Controls panel, set the boundary conditions in the engine components as described below.

For the cylinder (see Figure 19-27):

•Ensure that Cylinder is selected from the domain drop-down menu

•Set the Combustion dome regions type to Fixed and the Temperature to 450 K

•Set the Piston crown regions type to Fixed and the Temperature to 550 K

•Set the Cylinder wall regions type to Fixed and the Temperature to 500 K

Next, create an extra boundary region that defines a fixed temperature on the spark plug:

•In the Star Controls panel, select the Extra regions toggle button to create a region for the spark plug

•Under Extra regions, click Define to open the Boundary Tool

•In the Boundary Tool, click Display all to display all cylinder surface shells

•Click Keep picked to select the spark plug patches as shown in Figure 19-26

•Press q on the keyboard to exit from the pick mode

•Click Define in the Boundary Tool to assign the selected patches to the spark plug region

Figure 19-26 Spark plug patches

•Enter Spark Plug in the Name box

•Set the Regions type to Fixed wall

•Set the Temperature to 600 K

Figure 19-27 Two-stroke Star Controls > Boundary conditions panel for the cylinder

Now define flow boundaries for each of the seven transfer ports (see Figure 19-29):

•Select Grid Pieces from the domain drop-down menu

•Check that the Port wall regions setting is Adiabatic for all seven regions

•Under Extra regions, use the up/down scroll arrows to increase the number to

7 regions

•Click Define to open the Boundary Tool

•In the Boundary Tool, click Display all to display all surface shells

•Click Keep picked and select the transfer port flow patch, as shown in Figure 19-28

Transfer port

flow patch

Figure 19-28 Transfer port flow patch

•Press q on the keyboard to exit from the pick mode

•Click Define in the Boundary Tool to assign the displayed patch to the transfer port flow region

•Enter Transfer Flow 1 in the Name box

•Ensure that the Region type is set to Pressure

Figure 19-29 Two-stroke Star Controls > Boundary conditions panel for a transfer port

Following a similar procedure to that for initial conditions, specify that the remaining transfer flow boundaries should use the same boundary conditions as Region 1.

•Under Extra regions, select Region 2 from the drop-down menu

•Set Copy data of to Region 1 to use the same initial conditions as Region 1

•Reply Yes to the subsequent prompt to confirm the use of Region 1 parameters

•Enter Transfer Flow 2 in the Name box

•Pick the appropriate patches, as shown in Figure 19-30

•Repeat the previous steps (with appropriate names) for Region 3 and Region 4 as they are also transfer flow regions

For the exhaust ports (see Figure 19-32):

•Select Region 5 from the drop-down menu

•Under Extra regions, click Define to open the Boundary Tool

•In the Boundary Tool, click Display all to display all surface shells

•Click Keep picked to select the exhaust port flow patch as shown in Figure 19-31

Exhaust port

flow patch

Figure 19-31 Exhaust port flow patch

•Press q on the keyboard to exit from the pick mode

•Click Define in the Boundary Tool to define the displayed patch as the exhaust port flow region

•Enter Exhaust Flow 1 in the Name box

•Ensure that the Region type is set to Pressure

•Set the Absolute pressure to Constant and Mean using the drop-down menus

•Set the Pressure to 1.1 and select bar from the drop-down menu

•Set the Temperature to 350 and select K from the drop-down menu

Figure 19-32 Two-stroke Star Controls > Boundary conditions panel for an exhaust port

•Utilize the Copy data of menu to apply Region 5 boundary conditions to Region 6 and Region 7, as they too are exhaust flow boundaries. Figure 19-30 shows the relevant patch selections for each boundary region.

Figure 19-33 Exhaust port flow patches

Finally, select the Angelberger wall function model and combine all patches for a given boundary type into a single boundary region (see Figure 19-34):

•Select Global settings from the drop-down menu at the top of the panel