Create thermal boundary conditions for an aeroengine compressor

Practice defining thermal boundary conditions for an axisymmetric aeroengine compressor. You will create thermal streams, voids, and convecting zones.

Download and extract the part files.

Open the Simulation file

Open the model Simulation file and reset the dialog box settings.

  1. Choose File→Open and open aeroengine/CompressorAxisymmetric_fem1_sim1.sim.
  2. Choose File→Preferences→User Interface and on the Dialog and Precision page, reset the dialog box memory.
  3. Click OK.

Explore the model

The Simulation file contains the Thermomechanical solution, which already has some thermal and structural boundary conditions defined. You will explore the predefined thermal contacts, loads, and temperature and convection constrains boundary conditions.

  1. In the Simulation Navigator, expand the Thermomechanical → Simulation Objects nodes to investigate the defined thermal contacts.
  2. Expand the Loads and Constraints nodes to investigate the predefined boundary conditions.

Create a thermal stream on edges

Create a thermal stream on edges using formulas and parameters to define their mass flow, inlet temperature, and pressure values to model the thermal effects of a fluid moving on the surface of engine components.

  1. In the Simulation Navigator, under the Loads node, select the Stream 1 and Stream 2 check boxes to view the direction of the predefined streams.
  2. Choose Home tab→Loads and Conditions group→Load Type list→Thermal Stream .
  3. Verify that the Type list is set to One-Sided Stream on Edges.
  4. In the Name group, type Stream 3.
    The value of Boundary Condition ID is 3 for this thermal stream. This ID can be used in thermal-flow functions to connect thermal boundary conditions together.
  5. In the graphics window, select the edge (1). If the direction of the stream is different than the direction shown in the image, click Reverse Direction . Then select the edge (2) as shown. The Method is automatically set to Path Edges. This lets you select connected edges.
    There are 22 selected edges.
  6. Set the following options:
    • Fluid Materials=Air
    • Mass Flow=SMO(2) kg/s
    • Inlet Temperature=STO(2) °C
    • Absolute Pressure=(1.2)*(P026+0.12*(P030-P026)) MPa
    • Heat Transfer Coefficient=350 W/(m2·°C)

    The mass flow and the inlet temperature are defined using an expression, which contain built in thermal-flow functions. The SMO(2) function returns the outlet fluid mass flow of the thermal stream with ID 2. The STO(2) function returns the outlet temperature of the thermal stream with ID 2. Pressure is defined with a formula, using the predefined parameters. To investigate these parameters, choose Menu → Tools → Expressions.

    Note:
    Note: To define a magnitude using a formula, you can do one of the following:
    • Type the formula containing the parameters or functions in the magnitude box.
    • Click to the right of the magnitude box and choose:
      • Expression to define an expression using parameters.
      • Function to find available functions and insert them.
  7. Click Apply.

Create a thermal stream on a face

Create a thermal stream on the compressor blade face to simulate fluid flow on the surface.

  1. From the Type list, select One-Sided Stream on Faces.
  2. In the Name group, type Stream 4.
  3. Select the blade face as shown.
  4. In the Direction group, from the Specify Vector list, select XC-axis as the vector direction.
  5. Set the following options:
    • Fluid Materials=Air
    • Mass Flow=0.3*W26 kg/s
    • Inlet Temperature=0.5*(STO(1)-0[k]+t26-0[k]) + 0[k] °C
    • Absolute Pressure=0.1 MPa
    • Heat Transfer Coefficient=700 W/(m2·°C)
  6. Click OK.

Create a thermal convecting zone

Define a thermal convecting zone that models convection for a specific fluid temperature.

  1. Choose Home tab→Loads and Conditions group→Simulation Object Type list→Thermal Convecting Zone .
  2. In the graphics window, select the 7 connected edges shown.
  3. Set the following options:
    • Fluid Materials=Air
    • Temperature=T26 °C
    • Pressure=P026 MPa
    • Heat Transfer Coefficient=300 W/(m2·°C)
  4. Click OK.

Create a thermal void

Create a thermal void that models regions that are in contact with a single fluid volume, such as a cavity, characterized by a single temperature and a negligible heat capacity.

  1. Choose Home tab→Loads and Conditions group→Simulation Object Type list→Thermal Void .
  2. In the Name group, notice that the name is automatically set to V%%ID. This sets the load name to V1 in the Simulation Navigator, since the boundary condition ID is 1.
  3. In the Region 1 row, click Create Region
  4. In the graphics window, select the 9 connected edges shown.
  5. Set the following options:
    • Pressure=0.1 MPa
    • Heat Transfer Coefficient=100 W/(m2.°C)
  6. Click OK.

    The Thermal Void dialog box is opened.

  7. In the Simulation Navigator, under the Thermomechanical node, deselect the Loads node.
  8. In the Region 2 row, click Create Region.
  9. In the Region Objects group, from the Selection Method list, select Edge Path.
  10. In the graphics window, select the shown edge.
  11. In the Path Limits subgroup, select the Define End Point check box.
  12. From the Specify End Point, select Inferred Point.
  13. In the graphics window, select the end point as shown.
  14. Set the following options:
    • Pressure=0.1 MPa
    • Heat Transfer Coefficient=100 W/(m2.°C)
  15. Click OK.
    In the Thermal Void dialog box is opened.
  16. In the Region 3 row, click Create Region.
  17. In the graphics window, select the 3 edges shown.
  18. Set the following options:
    • Pressure=0.1 MPa
    • Heat Transfer Coefficient=100 W/(m2.°C)
  19. Click OK.
  20. In the Thermal Void dialog box, set the following:
    • Fluid Materials = Air
    • Heat Load = PWR(3) W
    Note:
    PWR(3) is a thermal function that returns the power input from feeding stream 3 into the void.
  21. Click OK.

Solve the model

  1. In the Simulation Navigator, right-click the Thermomechanical node and choose Solve.
  2. Click OK.
  3. Wait for Complete to display in the Analysis Job Monitor dialog box, before proceeding.
  4. In the Review Results dialog box, click No.
  5. Close the Information window.
  6. In the Analysis Job Monitor dialog box, click Cancel.

Display results

  1. In the Simulation Navigator, expand the Results node and double-click the Thermal node.
  2. In the Post Processing Navigator, expand the Thermal node and double-click the Temperature - Nodal node.
  3. Choose Results tab→Post View group→Edit Post View .
  4. In the Deformation tab, clear the Deformation check box.
  5. Click OK.
  6. Expand the Post View 1 → Mesh Collector nodes and clear the 0D Elements check box.
  7. In the Post Processing Navigator, under the Thermomechanical node, right-click the Structural node and choose Load.
  8. Expand the Structural → Increment 1,1.00s nodes and double-click Displacement-Nodal.
You have completed this lab.