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Reverse Engineering (RE) is the process transforming 3D geometry from neutral file formats (STEP, IGES, Parasolid, BREP) into a parametric CFturbo model.

The process is semi-automatic and consists of the following basic stages:

1.Creating/opening a CFturbo-project considering the desired machine type

2.Specifying the design point (Global setup)

3.Defining 3D geometry to be redesigned

4.Specifying parameters for automatic computation of the CFturbo model

5.Manual adjusting the CFturbo model to improve alignment with the initial 3D geometry

The stages 1. and 2. serve the purpose of specifying the turbomachinery's operating point as usual. The stages 3. and 4. are performed inside a separate dialog enabling the user to create a CFturbo model quickly and efficiently. In stage 5. the user can modify the redesigned CFturbo-model as needed within the ordinary design process (impellers, stators).

RE-dialog

The RE-dialog is divided into the following parts:

1.Steps (top)

•selecting the current active RE-step (loading 3D geometry, meridional redesign, blade redesign)

•contains information related to the current step

2.Imported geometry (left)

•loading external 3D geometry

•displaying the imported 3D geometry

•aligning geometry to 3D coordinate system of CFturbo model

•specifying CFturbo semantics for related geometry-elements (e. g. hub, shroud, blade)

3.Redesigned geometry (middle)

•presenting computation results of the CFturbo model as 3D geometry and meridional view

•specifying parameters for computation of the CFturbo model via 2D contour's context menu inside meridional view

4.Settings (right)

•specifying parameters for computation of the CFturbo model

5.Message tree (bottom right)

•contains information, warnings and errors occurred during the RE-process
 

 

Detailed description of the import process

1. Preparing the CFturbo-project

•Creating/opening a CFturbo-project considering the desired machine type

•Within Global setup: Specifying the design point suitable for the model to be redesigned

2. Load external 3D geometry

•Preconditions:

oRE-step Import must be selected at the top

oinput geometry must be represented by parametric surface data
(e. g. B-Spline surface, Cylindrical surface, etc.)

oinput geometry can be defined within a single or multiple files representing neutral file formats STEP, IGES, Parasolid or BREP

•Load geometry by clicking Load CAD data button or via drag & drop from a file explorer into the 3D-view.

•Loaded geometry is displayed in the 3D view and contained geometry elements are listed in the model tree left.

3. 3D alignment of loaded 3D geometry

•In order to obtain an accurate CFturbo model the loaded geometry has to be aligned sufficiently to the 3D coordinate system of the CFturbo-model.

•This essentially includes aligning rotation/symmetry axis of loaded geometry with the z-axis of the global coordinate system.

•Achieving a valid alignment can directly be done inside the Imported geometry section using Transformation panel.

4. Defining CFturbo-semantics on geometry elements

•In order to compute a CFturbo model from external 3D geometry a classification of imported 3D faces representing a specific CFturbo model part (e. g. hub, shroud, blade) must be applied (mapping).

•Mappings are applied context sensitive related to the currently selected RE-step (Meridian: Hub, Shroud/Tip, Blade: Main blade, Splitter blade) at the top.

•This can be achieved by selecting a single or multiple 3D face(s) in the 3D view or model tree and using one of the following options:

oopening the context menu by clicking right mouse button and selecting an appropriate CFturbo model part (see first image below)

oclicking buttons representing CFturbo model parts next to the model tree (see first image below)

ousing drag & drop of a model tree node from the Imported geometry section onto the model tree node related to a CFturbo model part in the Redesigned geometry section (see second image below)

•Mappings of 3D face(s) to CFturbo-model parts are represented by an information in the model tree of the Imported geometry section and by explicit nodes in the model tree of the Redesigned geometry section.

•Mappings can be deleted using one of the following options:

oopening the context menu of the related tree node in the Redesigned geometry section and choosing the option Remove mapping

oclicking button Remove mapping next to the model tree

5. Computation of CFturbo model

•Updating redesigned model:

owithin RE-step Meridian: computation of the CFturbo model is performed automatically related to user inputs

owithin RE-step Blade: computation of the CFturbo model is started manually by pressing Update design in the Settings section or is performed automatically related to user inputs in case of activated Automatic design update

oAutomatic computations are triggered by adding/removing assignments of 3D-faces to CFturbo model parts and by changing parameters in the Settings section and in the context menu of 2D meridional contours

•Parameters:

•Results of computations are displayed inside the Redesigned geometry section:

o2D contours in z,r coordinate system inside 2D meridional view:

▪Hub / Shroud / Tip contours

▪Blade's Leading / Trailing edge

▪Spans (light grey: contours for blade intersection; black: valid blade intersection; orange: invalid blade intersection)

o3D design model in the 3D-view (incl. model tree)

oIndication of validity of user-defined input geometry assigned to CFturbo model parts by model tree node color
(green: valid, red: invalid/incomplete)

oWarnings/Errors during computation inside the message list bottom right

6. Finalization of import process

•After computation of a valid CFturbo model the Reverse engineering dialog can be closed by pressing OK button (irreversible)

•Now the CFturbo project contains the new component which has to be activated finally

Example

In this section the RE-process from initial input geometry to a CFturbo design is documented for a mixed-flow pump exemplarily. Any redesigned CFturbo model can further be modified as needed inside the ordinary design process.

1. Preparing the CFturbo-project

•Creating a new CFturbo-project

•Specifying the design point within Global setup

•Adding a new component and specifying the import-format

   

2. Loading and preparing external 3D geometry

•load external 3D geometry from neutral 3D file formats

•align loaded geometry with the coordinate system of the CFturbo model

ocollinear alignment of rotation axis with the z-axis

ofluid flow direction in positive z-axis direction (for turbines: opposite direction!)

•define desired rotation direction of the loaded geometry

3. Meridional redesign

•Selection of Step ❷ Meridian

•Map 3D-faces to Hub / Shroud

•It's not necessary to select all 3D-faces representing the complete hub-/shroud-surface. Instead a single face covering the surface from inlet to outlet is sufficient.

4. Blade redesign

•Selection of Step ❸ Blade

•Map 3D-faces of a single blade to Blade

•select the Blade edge shape of the loaded blade geometry (Rounded, Blunt)

•choose sufficient Blade intersection parameters

odefault Number of spans is sufficient in general

ooffsets can be increased in case of large blade root fillets (optional)

•press Update design in order to compute the redesigned geometry

5. Finalization

•close RE-dialog by pressing OK after a valid design model is computed
(initially opened/created project now contains the redesigned CFturbo-model)

•activate the redesigned component (in order to modify the design)

•save the created design by saving the project

 

Possible warnings