10.3.5. Defining Geometry from Generated CAD: CAD From Profile Points

If your geometry is defined by profile point data, you can use the CAD From Profile Points input mode to have TurboGrid automatically generate and import a CAD model created from the profile points. The CAD model is then used as the geometry for all TurboGrid meshing operations. Note that the profile point data can be re-read at any time to update the CAD model.

When this input mode is selected, you can also define additional geometry features to include in the CAD model, such as blade blends (fillets) or partial tips. For details, see Blade CAD Features.

Note:

  • When you use the CAD From Profile Points input mode, an Ansys BladeModeler license is required.

  • The CAD From Profile Points input mode is available only in stand-alone mode; it is not supported in Ansys Workbench.

  • If you plan to include additional geometry features, you might want to also generate the geometry without those features in order to evaluate the effect on the geometry of generating CAD. Specifically, you might want to compare the geometry obtained from profile points alone (via Input Mode set to Profile Points) with the geometry obtained by generating CAD from the same profile points (via Input Mode set to CAD From Profile Points).

  • If used with Release 2023 R2 or newer of TurboGrid, state and session files recorded from Releases 2022 R2 or 2023 R1 might include tip clearance in the CAD file, rather than apply tip clearance in TurboGrid after loading the CAD file. If you want to retain the previous behavior, for example because applications other than TurboGrid use, and expect no tip clearance in, the CAD file, you can modify such state or session files to effectively turn off Include Tip Clearance in CAD File. As a guide, examine a state or session file that was recorded in Release 2023 R2 or newer, with Include Tip Clearance in CAD File being turned off in the geometry browser. The Include Tip Clearance in CAD File setting is described in Geometry Browser Settings (CAD From Profile Points Mode).

To generate CAD from profile point data:

  1. Load the profile point data.

    For details, see Defining Geometry from Profile Points bearing in mind the requirement to run in stand-alone mode.

  2. In the Geometry workspace, open the geometry browser and set Input Mode to CAD From Profile Points.

  3. Configure the settings in the geometry browser.

    For details, see Geometry Browser Settings (CAD From Profile Points Mode).

  4. Click Apply And Generate CAD.

    Note:

    • It takes a significant amount of time for the CAD file to be generated (or regenerated, if generated previously).

    • The CAD geometry is only ever regenerated on demand, that is, it will not be updated automatically if the profile point data changes or if the blade blend settings are modified. If you make changes that will affect the CAD geometry, you must then manually regenerate the CAD geometry, either using the geometry browser or by using File > Update Geometry.

      After loading a state file that refers to an existing Parasolid file created from the CAD From Profile Points input mode, TurboGrid assumes that the existing CAD geometry is up-to-date with any relevant settings in the state file, for example, the blade blend settings (see Blade CAD Features). Therefore, such objects will appear to be up-to-date in the object selector even if they are not. To avoid inadvertently using an out-of-date CAD geometry, you can make it a practice to manually regenerate the CAD geometry after loading the state file, if you are not sure whether it is up-to-date or not.

The following topics are discussed:

 

10.3.5.1. Geometry Browser Settings (CAD From Profile Points Mode)

  • On the Input Selection tab:

    The Generated CAD Definition > File Name setting holds the name of a CAD file. Specify a file name (relative or full path optional) that has the extension ".x_b", for example "geometry.x_b". You can click the Browse   icon to select an existing file (to be overwritten) using a browser.

    The remaining settings on the Input Selection tab are the same as the corresponding settings available for the Profile Points input mode. For details, see Geometry Browser Settings (Profile Points Mode).

  • On the CAD Properties tab:

    The CAD Scaling setting can be set to Actual Size or Small Model Scaling. You should consider selecting the Small Model Scaling option if the length scale of the blade (or smallest blade of a blade set) is less than a few centimeters, especially if the CAD geometry fails to be generated with the Actual Size option or if the leading/trailing edge of the blade is not properly resolved. As a consequence of using the Small Model Scaling option, the geometry is scaled in the resulting CAD file. Although TurboGrid takes account of this scaling, loading the generated CAD geometry into other products results in scaled geometry.

    The Blend Style setting has the following options:

    • Approximate Blend (Low Fidelity Geometry Only)

      With this option, the generated CAD geometry includes a low-fidelity representation of the blade blend but no high-fidelity representation of the blade blend. Use this option to save time if you intend to produce a mesh only for low-fidelity geometry.

    • True Blend (Low and High Fidelity Geometry)

      With this option, the generated CAD geometry includes both a low-fidelity representation of the blade blend and a high-fidelity representation of the blade blend. In the context of TurboGrid, a blade blend represented with high-fidelity geometry is called a true blend and is considered to be a type of complex blade end. Use this option if you intend to produce a mesh for high-fidelity geometry. Note that high-fidelity geometry requires meshing with ATM3D topology. For related information, see Meshing High-Fidelity Geometry.

    Figure 10.6: Approximate Blend versus True Blend shows that an approximate blend meets the hub/shroud at a non-zero angle whereas a true blend meets asymptotically.

    Include Tip Clearance in CAD File, when selected, causes any specified tip clearance from the Hub Tip and/or Shroud Tip objects to be included in the resulting CAD geometry. Include Tip Clearance in CAD File is selected by default for new cases.

    Details on the Include Tip Clearance in CAD File setting:

    • To provide support for all tip clearance options, ensure that Include Tip Clearance in CAD File is selected. In particular, the Profile Number tip clearance option requires that Include Tip Clearance in CAD File is selected; for details, see Clearance Type.

    • If you want to use the CAD geometry in other software with the tip clearance included, ensure that Include Tip Clearance in CAD File is selected.

    • If Include Tip Clearance in CAD File is not selected, then the CAD geometry does not include tip clearance from the Hub Tip and Shroud Tip objects, and, for eligible tip clearance types only, TurboGrid applies such tip clearance after loading the CAD geometry.

      Note that the mesh can differ slightly depending on whether Include Tip Clearance in CAD File is selected. You might want to clear the Include Tip Clearance in CAD File check box to, for example, revert to the behavior prior to Release 2023 R2.

    • Most state and session files recorded from Releases 2022 R2 or 2023 R1 will continue to operate as before; that is, the tip clearance will not be included in the CAD file and will instead be applied by TurboGrid after loading the CAD file. However, some session files from Releases 2022 R2 and 2023 R1 (those recorded without applying settings from the geometry browser after setting CAD From Profile Points input mode) will effectively have Include Tip Clearance in CAD File selected, and so will add the specified tip clearance to the CAD file.

      If you want to retain the previous behavior, for example because applications other than TurboGrid use, and expect no tip clearance in, the CAD file, you can modify such state or session files to effectively turn off Include Tip Clearance in CAD File. As a guide, examine a state or session file that was recorded in Release 2023 R2 or newer, with Include Tip Clearance in CAD File being turned off in the geometry browser.

    The Profile Points For CAD Generation > Method setting is used to determine whether the CAD geometry is generated directly from the original user-supplied profile points (in the specified curve files) or whether the CAD geometry is generated based on the surfaces already created by TurboGrid from the profile points.

    If the original profile points are to be re-used, then each profile must have the same number of points. Tagging the leading and trailing edge points in the file is highly recommended to help ensure that the CAD geometry can be created successfully.

    The Profile Points For CAD Generation > Method setting can be set to Extract Profile Points From Geometry or Use Original Profile Points. If you select Use Original Profile Points, then the original profile points will be re-used (preserved) if possible. If the original profile points cannot be re-used, or if you select Extract Profile Points From Geometry, then new profile points are generated based on the geometry; the number and distribution of new profile points are generally different than the number and distribution of the original profile points. After you click Apply And Generate CAD with Use Original Profile Points selected, the object editor indicates whether original points were successfully preserved. If you select Extract Profile Points From Geometry, there is no need to tag the leading and trailing edge points in the data file, and no need to ensure the same number of points per profile.

  • Apply And Generate CAD

    Clicking the Apply And Generate CAD button applies the geometry browser settings and then generates (or regenerates) the CAD geometry.

    Generation (or regeneration) of the CAD geometry involves running Ansys BladeEditor temporarily in the background to generate a Parasolid file and associated TurboGrid Initialization file, then loading those two files into TurboGrid, resulting in new/updated CAD objects and (in accordance with the contents of the TurboGrid Initialization file) new/updated topological entities in the Geometry workspace tree.

 

10.3.5.2. Limitations of CAD From Profile Points Input Mode

  • The CAD From Profile Points input mode is available only in stand-alone mode; it is not supported in Ansys Workbench.

  • Blade blends and partial tips cannot be enabled together.

  • Blade blends and partial tips are not available if any Hub Tip or Shroud Tip has been enabled.

  • Blade stagger cannot be enabled if blade blends are enabled.

  • Secondary flow paths are not supported.

  • There is no support for blades with Cut-off or square leading or trailing edges.

  • There is no support for splitter blades.

  • The CAD From Profile Points input mode is supported only if the rotation axis is Z.

  • All curves are generated using the Bspline option rather than the Piece-wise linear option, regardless of the settings. For example, the Hub object > Data Hub tab > Curve Type setting is ignored.