Step 4: Mixing Plane

Define $\rightarrow$ Mixing Planes...

  In this step, you will create the mixing plane between the pressure outlet of the rotor and the pressure inlet of the stator.

1.   Select pressure-outlet-rotor from the Upstream Zone selection list.

2.   Select pressure-inlet-stator from the Downstream Zone selection list.

3.   Retain the selection of Area in the Averaging Method list.

4.   Click Create and close the Mixing Planes dialog box.

   ANSYS FLUENT will name the mixing plane by combining the names of the zones selected as the Upstream Zone and Downstream Zone. This new name will be displayed in the Mixing Plane list.

  The essential idea behind the mixing plane concept is that each fluid zone (stator and rotor) is solved as a steady-state problem. At some prescribed iteration interval, the flow data at the mixing plane interface are averaged in the circumferential direction on both the rotor outlet and the stator inlet boundaries. ANSYS FLUENT uses these circumferential averages to define "profiles'' of flow properties. These profiles are then used to update boundary conditions along the two zones of the mixing plane interface.

In this example, profiles of averaged total pressure ( $p_0$), static pressure ( $p_s$), direction cosines of the local flow angles in the radial, tangential, and axial directions ( $\alpha_r, \alpha_t, \alpha_z$), total temperature ( $T_0$), turbulent kinetic energy ( $k$), and turbulent dissipation rate ( $\epsilon$) are computed at the rotor exit and used to update boundary conditions at the stator inlet. Likewise, the same profiles, except for that of total pressure are computed at the stator inlet and used as a boundary condition on the rotor exit.

The default method for calculating mixing plane profiles uses an area-weighted averaging approach. This method allows reasonable profiles of all variables to be created regarding of the mesh topology. In some cases, a mass flow-weighted averaging may be appropriate (for example, with compressible turbomachinery flows). For such cases, the Mass option can be enabled as shown. A third averaging approach (the Mixed-Out average) is also available for flows with ideal gases. Refer to this section in the separate Theory Guide for more information on these averaging methods.

  You can view the profiles computed at the rotor exit and stator inlet in the Profiles dialog box.

Define $\rightarrow$ Profiles...

  You will also see that these profiles appear in the boundary conditions dialog boxes for the rotor exit and stator inlet.

For more information on mixing planes, see this section in the separate User's Guide.