The configuration is presenting a hub defined with a control point at R=0. A bulb is automatically detected and flow paths controls are added.
41.Adapt control line close to the bulb
•
Click-left on control line when highlighted in yellow•
Click-left on control point defining the control line•
Move control point at desired location•
Click-left on control point to validate its new location•
Click-left on Select All Rows•
Click-left on Generate Flow Paths42.Adapt flow paths distribution in bulb
•
Click-left on•
Deactivate Singular line to impose a butterfly topology in the bulbThree topologies are available for bulbs: sharp (H-mesh), rounded (C-mesh) or radial. With C mesh, the zero radius area can be meshed with a singular line or a butterfly topology.
C --> R C --> L M M Click Left Singular line Butterfly topology
Bypass Configuration
Mesh Generation
Click-left on the number of nodes, make the proper modification in the entry box and press <Enter> to confirm the modification.
•
Close dialog box•
Click-left on Select All Rows•
Click-left on Generate Flow Paths43.Check quality of the flow paths as presented in step 38
3-2.5
Blade-to-Blade Control
44.Click on Generate B2B
When plotting all rows on hub (active layer set 0% by default), the row 2 is not appearing in the blade-to-blade view because it is not intersecting the hub. To check the mesh on row 2, an active layer intersecting the row 2 should be
row 1 row 3
row 4
Mesh Generation
Bypass Configuration
45.Go to
Mesh Control Row Mesh Control B2B Mesh Topology Control Topology
By default, non-matching connections are applied at periodic boundaries. Matching connections at periodic boundaries can be obtained by activating the Matching Periodicity check button. Press Re(set) Default Topology to re- generate the mesh in the blade-to-blade plane.
In most cases, the presence of non-matching connections somehow improves the orthogonality in the overall mesh. This is especially true in highly stag- gered configurations.
46.Keep Matching Periodicity deactivated and all other data identical
In several turbomachinery types, the blades are highly staggered (Automatic
High Staggered Blade Detection within AutoGrid™). If the solid angle at the inlet (outlet) of the machine becomes greater than 450 and if the location of
the inlet (outlet) limits of the domain is close to the leading edge (trailing edge) of the blades, then the default topology is not suitable anymore since the cells located near the inlet (outlet) boundary become very skewed. To improve this unexpected behaviour, AutoGrid™ uses the High Staggered Blade Opti-
mization.
47.Deactivate Topology option
48.Go to Mesh Control Row Mesh Control B2B Mesh Topology Control -> Grid Points to control the number of grid points in the blade-to-blade view if necessary
49.Click-left on the number of nodes, make the proper modification in the entry box and press <Enter> to confirm the modification
The number of points specified is recommended to be 4xn + 1 (where n is an
Bypass Configuration
Mesh Generation
50.Visualize the result in blade-to-blade view after selecting Generate B2B to regenerate the flow paths and the mesh in blade-to-blade plane.
51.Deactivate Grid Points option
52.Close the dialog box.
53.Go to Mesh Control-> Active B2B Layer to specify the flow path (layer) on which the blade-to-blade mesh will be plotted in the blade-to-blade view
By default, the active layer is the hub of the machine (Active Layer (%span) set to 0). The layer selected for visualization is defined in percentage of span, going from hub (0%) to shroud (100%) and is applied on active row(s).
54.Click-left on Select All Rows
55.Enter for example <50> <Enter> in order to visualize the mesh at 50% span
56.Select Generate B2B to regenerate the blade-to-blade mesh on new specified layer in the blade-to-blade view
Detailed analysis of mesh quality can be performed on Blade-to-Blade mesh after generation. Information on orthogonality, aspect ratio and expansion ratio can be outlined in this window using the Type pull-down menu and plot- ted in the blade-to-blade view on active layer selected in Mesh Control/ Active B2B Layer.
57.Check for grid quality by clicking on
58.Select quality criteria using the Type pull-down menu
59.Click-left on Show chart to visualize the distribution of selected criteria in the form of an histogram. The histogram is drawn for each row
60.Click-left on part of the histogram to plot the concerned cells in the blade-to-blade view
61.Click-left on More info button to obtain information about minimum and maximum values of the selected criteria
Mesh Generation
Bypass Configuration
62.Close the dialog box
63.Go to Mesh Control -> Row Mesh Control -> Optimization Control to adapt the mesh optimization parameters if necessary to enhance the quality of the mesh
Optimization is performed in the form of smoothing and is executed on each layer using multi-block elliptic techniques. The number of Optimization Steps represents the number of iterations performed with the elliptic smoother. By default, 100 iterations are applied.
64.Keep default Optimization Steps and all other data identical
65.Close the dialog box