CAD data can be used for the geometry of the blades and main passage, and for secondary flow paths.
You can load CAD data from:
A BladeEditor Geometry cell in Workbench, or
A Parasolid or other CAD file in stand-alone mode.
Note: If TurboGrid crashes while loading CAD geometry, there might be a failure in creating internal representations of the CAD blade surfaces for meshing. A possible workaround is to perform one or more of the following steps, using the Command Editor dialog box to make CCL changes:
Before loading the geometry set Stop Before Blade Approximate Surface Generation in BLADE SET to true.
Load the geometry.
Increase Surface Parameterization Tolerance Multiplier in BLADE SET to 10.0.
Increase Surface Parameterization Number Of Splits in BLADE SET to 200.
Change Parametric Surface Generation Smoother in the Blade object(s) to Angle-based.
Change Display Trimmed Surfaces in the Blade object(s) to false.
Reset Stop Before Blade Approximate Surface Generation in BLADE SET to false.
The following topics are discussed.
To load CAD data from a BladeEditor Geometry cell:
In Ansys Workbench, attach a Geometry cell (containing a BladeEditor geometry) upstream of the Turbo Mesh cell.
Specify which exported blade(s) to load into TurboGrid by editing the Turbo Mesh cell properties. See TurboGrid Turbo Mesh Cell Properties in the TurboSystem User's Guide for more information.
Note:
This method is applicable only for native BladeEditor blades (not general CAD geometry imported into DesignModeler). If a geometry that is to be imported from BladeEditor fits within a cube of edge length 10 cm, the DesignModeler session unit (see Units Menu in the Ansys DesignModeler User's Guide) should be set to Micrometer for better geometry precision. For details, see Export to Ansys TurboGrid in the TurboSystem User's Guide.
When a blade is passed from BladeEditor to TurboGrid (so that a CFD mesh can be made by TurboGrid), two versions of the geometry are passed:
The "display geometry", which is the true geometry designed in BladeEditor, and
The "meshing geometry", which is used by TurboGrid in constructing the mesh.
The meshing geometry is slightly different from the display geometry because it must meet TurboGrid’s mesh generation requirements. For example, the meshing geometry has extended surfaces that overlap so that TurboGrid can reliably locate surface intersections.
In the Mesh workspace, the display geometry can be visually compared with the mesh. In the Geometry workspace, you can view both the display geometry and the meshing geometry by turning on visibility of the corresponding CAD objects listed in the tree.
In particular, for blades with blends (fillets) from BladeEditor, there will typically be a noticeable difference between the mesh and the display geometry shown in the Mesh workspace, and a noticeable difference between the meshing geometry and display geometry shown in the Geometry workspace. The overall difference in fillet geometry (for example, the amount of flow blockage) can be affected by changing fillet-related parameters in BladeEditor.
If you have a geometry defined by profile points and you want to use
BladeEditor to add blends using the rolling ball process with a constant radius,
consider using the CAD From Profile Points input mode
and add a blade blend object in the Mesh workspace.
For details, see Defining Geometry from Generated CAD: CAD From Profile Points and Blade CAD Features.
For other types of blade blends created in BladeEditor, the following troubleshooting notes apply:
If you experience a problem with mesh quality near a cut-off edge (LE or TE) and near a blade fillet, then adjusting the following CCL parameters might help:
Number Of Hub To Shroud Constant Span SplitsMesh Curves Tesselation Number Of Power Samples = 8Mesh Curves Tesselation Number Of Power Samples Override = true
If a blade fillet looks wavy where it meets the hub/shroud (more likely for cases with high hub/shroud curvature), increasing the following CCL parameters might help:
Turbo Transform Background Mesh SizeTurbo Transform Background Mesh Size For Topology
To load CAD data from a CAD input file (for example, a Parasolid file):
In TurboGrid in stand-alone mode, in the Geometry workspace, open the geometry browser, set Input Mode to
CAD(orProfile Points With Secondary CAD) and configure the applicable settings in the geometry browser.
Note: When a CAD blade is loaded from a file into TurboGrid, two versions of the geometry might be displayed:
When available, the "display geometry", which is the best representation of the true geometry, is displayed in the Geometry workspace.
The "meshing geometry", which is used by TurboGrid in constructing the mesh, is displayed in the Mesh workspace.
The meshing geometry is slightly different from the display geometry because it must meet TurboGrid’s mesh generation requirements. For example, the meshing geometry has extended surfaces that overlap so that TurboGrid can reliably locate surface intersections.
In the Mesh workspace, the display geometry can be visually compared with the mesh. In the Geometry workspace, you can view both the display geometry (when available) and the meshing geometry by turning on visibility of the corresponding CAD objects listed in the tree.
The Geometry workspace tree holds CAD objects and can be used to visually check that the correct CAD geometry is imported.
The main objects in the Geometry workspace are:
|
The Topological Entity Instances Object |
This object holds topological entities, each of which defines a key geometric feature needed by TurboGrid. The topological entities refer to CAD objects, either directly or through child objects. |
|
The CAD Families Object |
This object holds CAD objects that each define a geometric feature that was imported from a CAD file. You can select different CAD objects to view them in the 3D Viewer. Specific objects from the CAD file can be used by TurboGrid after they are assigned to topological entities. |
Some topological entities can be edited in the object editor. To open the object editor, double-click an object in the tree or select an object and then press Enter. In particular:
Each topological entity that can refer to CAD objects has, in its object editor, a Location setting for assigning CAD objects. Beside this setting is a CAD Entity Selector
icon for opening the CAD Region Entities dialog box, which you can use to select CAD objects.Note that an alternative method for assigning CAD objects to a topological entity is to select CAD objects from the
CAD Familiesbranch of the tree and use the shortcut menu.The blade topological entity has an object editor, with self-explanatory settings Blade Name, Leading Edge Type, and Trailing Edge Type.
The
ComplexBladeEndtopological entity has an object editor. For details, see Complex Blade End.
To access the geometry browser, switch to the Geometry workspace and then, if necessary, double-click a high-level object
(either the Topological Entity Instances object or the CAD Families object) in the object selector.
The geometry browser CAD-related settings, which are available for the CAD and
Profile Points With Secondary CAD input modes, are described next:
Set File Name to the name of a CAD file (for example, *.x_b exported from BladeEditor).
Optionally select Named Selection Processing to have TurboGrid create CAD families for named selections in the CAD file. You should select this option for Parasolid and ICEM CAD files, except for Parasolid files written by SpaceClaim; for the latter, you should clear this check box in order to have CAD entities organized into families corresponding to the organization in SpaceClaim.
Optionally select Specify CAD Geometry Units and specify units for CAD Length Units. If you do not specify units, TurboGrid will attempt to determine the units from the file contents; in such cases you should confirm that the units are correct by observing the resulting geometry in the 3D Viewer.
These settings are similar to the Rotation settings of the Machine Data object. For details, see Rotation.
A rotating machine component is made up of adjacent blades that are equally spaced around the circumference of the machine. The Theta extent of one blade set is calculated as 360 degrees divided by the number of main blades. Many rotating machine components have secondary and tertiary blades that are placed between the main blades. These are often called splitter blades. A blade set contains one main blade and optional splitter blades that repeat cyclically around the axis of the rotating machine component.
For rotating machine components without any splitter blades, the number of blade sets equals the total number of blades.
TurboGrid creates a mesh for one blade set only. The mesh can be copied and rotated using an Ansys CFX Pre-processor, if necessary, before it is solved in an Ansys CFX Solver.
TurboGrid uses a specific set of geometric inputs. Because CAD geometry is more general, there are some CAD features that cannot be used by TurboGrid. A list of some such features follows:
You cannot transform imported CAD geometry.
Inlet and outlet trimming is governed by selected CAD curves.