Model finishing

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Model finishing

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► IMPELLER | Model finishing

The dialog offers different possibilities to design the connection between blade, hub and shroud.

 

No model finishing

 

 

Extend blade only

Extends blades through hub and shroud for later trimming in a CAD-system.

Additionally, extends blades through leading/ trailing edge, if it is fixed as well as simple and trimmed on inlet/ outlet.

Solid trimming

Meridian.Flow domain

Meridian.Flow domain

 

Meridian.Material domain

Meridian.Material domain

Trims blades on hub, shroud and possibly leading and trailing edge.

The solid trimming affects only the solids (and solid faces) of Meridian.Flow domain, Meridian.Material domain, CFD setup.Segment and Blade.

Trimming is a time-consuming operation (up to 30 seconds).

Because only solids are trimmed, point-based exports cannot take advantage of this operation.

 

Details:

Solid trimming is based on a segment. If no segment is defined,  it is created temporarily, not visible to the user.

Internal workflow:

The blades are extended (see Extend blade only)

A single blade is trimmed with Meridian.Flow domain

From Meridian.Flow domain, a segment is cut. In this way the trimmed Segment.Real geometry is created.

CFD setup option: If there is an Extension or RSI connection, Segment.Real geometry is fused with Segment.Extension and Segment.RSI connection. In this way, Segment.Flow domain is created.

Segment.Flow domain is copied multiple times. The copies  are rotated and sewed in order to create a new Meridian.Flow domain.

If hub and shroud solids have been defined, a Meridian.Material domain is created by fusing the blades and the solids of hub and shroud.

CFD setup option: If Blade projection was chosen, the corresponding projection surfaces are exactly trimmed.

Option: Blade root fillet

The edges between blade and hub/ shroud are rounded.

The fillet affects only the solids (and solid faces) of Meridian.Flow domain, Meridian.Material domain and CFD setup.Segment.

The fillet radius should not be larger than the recommended value.

Limitations

Fillet creation is not possible if the fillets of two neighboring blades would meet or if the fillet would protrude beyond the impeller inlet or outlet.

Fillet creation is not possible if the blade has very sharp edges, i.e. if the fillet radius is much larger than the edge radius.

Update modes

<OK>

The configuration is saved in the project, but the 3D-model is not updating.

<OK + Run>

The configuration is saved in the project and the 3D-model is updating using the model finishing options.

 

The model finishing can be executed globally for all vaned components by PROJECT/ Model finishing.

Possible warnings

Problem

Possible solutions

Extend/solid trimming may fail due to tangential difference between hub and shroud at leading/trailing edge, or low number of spans.

Very low number of spans

Increase the number of spans up to at least 4

Finishing type was reset to "No model finishing". Solid trimming impossible for nearly tangential contour at dH = 0.

Solid trimming is not supported if the hub contour is nearly tangential to the Z-axis.

Change the hub contour to form a bigger angle to the Z-axis.

Finishing type was reset to "No model finishing". Solid trimming impossible when blades exceed meridional boundaries.

Solid trimming is not possible if the blade exceeds the meridional boundaries (caused by the blade thickness).

Change blade design so that it fits into meridional boundaries, e.g. change Blade edges

Fillets not supported.

Fillets are not supported if solid trimming is not possible.

-

Fillets creation on shroud deactivated.

Fillets on shroud are not supported for unshrouded designs.

-

Curvature of Leading edge/Trailing edge/Blade edges at Hub/Shroud could be too large for fillet creation.

Sharp Blade edges could prohibit fillet creation between blade and hub/shroud and could cause long computation time respectively.

Less sharp design of blade edges or reduction/deactivation of fillet radius.

3D-Error: Finishing failed!

Inlet (nearly) tangential to hub or shroud

Change Meridional contour: Avoid tangentiality

3D-Error: Finishing failed! (Could not extend blade)

Extending the blade to a scaled Hub/ Shroud surface failed.

See solution of Error while extrapolating Blade to reach Hub/ Shroud surface

3D-Error: Finishing failed! (Could not trim solids of Blades and Flow domain)

Trimming a single blade with Meridian.Flow domain failed.

Try using a different number of data points

3D-Error: Finishing failed! (Could not create fillet)

Fillet creation at blade root failed (see limitations).

Decrease fillet radius
or
Deactivate fillet

3D-Error: Finishing failed! (Creating trimmed segment)

Cutting a segment from Meridian.Flow domain failed.

Change the segment type

3D-Error: Finishing failed! (Fusing solids)

Fusing of real geometry with CFD setup components (Extension or RSI connection) failed.

Increase the number of spans
or
Remove Extension / RSI connection from CFD setup

3D-Error: Finishing failed! (Creating new Flow domain from segment)

Creating a new Meridian.Flow domain from Segment.Flow domain failed.

Change the segment type

3D-Error: Finishing failed! (Creating Material domain from Flow domain)

Creating a Meridian.Material domain failed.

Deactivate hub and shroud solid

3D-Error: Blade projection to RSI failed!

Projection of blade to RSI (Extension) failed.

Change CFD setup: Modify Extension or remove Blade projection

3D-Error: Blade tip projection to casing failed!

Projection of blade to casing (shroud) failed.

Change CFD setup: Remove Blade projection or RSI connection