Setting Boundary Conditions and Values

All wall boundaries, including the baffle, are adiabatic, no-slip walls. Since this is the default wall boundary type, no changes are required here. The default settings are also suitable for the outlet, so the only boundary conditions that need to be specified are for the four inlets.

Select the Air_Inlet1 > Physics Conditions > Velocity Specification node.

In the Properties window, change the Method property to Components.

Select the Turbulence Specification node and, in the Properties window, change the Method property to Intensity + Length Scale.

The air and fuel will be made to swirl on entry to the combustor by specifying inlet velocity vectors in a new cylindrical coordinate system. To create the latter:

Open the Tools node, right-click the Coordinate Systems node and then select New > Cylindrical Coordinate System.

A new cylindrical coordinate system called Cylindrical 1 will be created. The default properties of this system are suitable for the current problem.

Return to the Air_Inlet1 node and select the Physics Values > Velocity node.

In the Properties window, change the Coordinate System property to Cylindrical 1.

Select the Mass Fraction > Constant node.

In the Properties window, click on the customizer button for the Value property to open the Constant - Value dialog.

Enter 0.233 as the O2 value and 0.767 as the N2 value.

Click OK.

Continue by enter the following data for the other nodes under the Physics Values node:

Static Temperature: 293 K

Turbulence Intensity: 0.1

Velocity: -11, -24, 42 m/s

The boundary conditions required for Air_Inlet1 are identical to those for Air_Inlet2 and very similar to those for Air_Inlet3 and Fuel_Inlet. Therefore, it is convenient to copy the Air_Inlet1 conditions to the other three inlet boundaries and make changes where necessary.

Right-click the Air_Inlet1 node and select Copy.

Right-click the nodes of each of the other three inlet boundaries, selecting Paste each time.

Select the Air_Inlet3 > Physics Values > Velocity > Constant node.

In the Properties window, enter 0,0,15 m/s for the Value property.

Select the Fuel_Inlet > Physics Values > Mass Fraction > Constant node.

Click the customizer button for the Value property and change the values in the Constant - Value dialog as shown below.

Click OK.

Select the Fuel_Inlet > Velocity > Constant node.

In the Properties window enter -28,-60,100 m/s for the Value property.