Setting Boundary Conditions and Values

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

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 the inlet velocity vectors in a new, cylindrical coordinate system. To create the latter:

Right-click the Tools > Coordinate Systems node and then select New > Cylindrical Coordinate System.

A new cylindrical coordinate system named 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 Constant node within the Velocity node.

In the Properties window, enter -11,-24,42 m/s for the Value property.

Select the Constant node within the Turbulence Intensity node and change the Value property to 0.1.

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 boundary 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 > Mixture Fraction > Constant node.

In the Properties window, enter a Value of 1.0.

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

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