1. Overview

BladeXtractor extracts profile (airfoil) point coordinates from 3D blade CAD files of axial compressors and turbines.

Use Cases

When working with turbomachinery blades, you often have a 3D CAD model but need accurate airfoil point coordinates:

• Reverse Engineering: Analyze existing blade geometry to extract design parameters or use as baseline data for new designs
• CFD Mesh Generation: Accurate blade surface point coordinates are required when generating meshes for computational fluid dynamics analysis
• Blade Design Verification: Verify that CAD models are generated according to design intent by examining cross-sectional shapes
• Software Integration: Transfer geometry data to other turbomachinery design/analysis tools

BladeXtractor automatically extracts airfoil sections at desired Span positions from STEP files and converts them into ready-to-use point coordinate data.

How It Works

1. Load Blade STEP File: Load existing 3D blade geometry
2. Load Hub/Shroud Curves: Define flow path geometry on the meridional plane
3. Generate Stream Surface: Create revolution surfaces connecting Hub-Shroud at specified Span positions
4. Extract Intersection: Calculate intersection curves between blade and stream surface
5. Output Point Coordinates: Divide intersection curves uniformly and output 3D point coordinates

                          Shroud
                        ──
                       ╱  ╲
                      ╱────╲  ← Stream Surface (span=0.5)
                     ╱      ╲
                    ╱        ╲
              Hub  ╱──────────╲
                ← Z-Axis (Rotation Axis) →

Output Format

• .curve format compatible with Ansys® TurboGrid®
• 301 points per Span (closed loop: TE -> LE -> TE)
• Hub/Shroud meridional curves (entire flow path range)

2. System Requirements

• Windows 10/11 (64-bit)
• Display: 1280x800 or higher recommended

Program Files

3. Preparing Input Files

3.1 Blade STEP File

• Format: STEP (*.stp, *.step)
• Coordinate System: Z-axis is the rotation axis
• Units: mm (millimeters)

Note: The blade must be a single blade. Full rotor/stator assemblies are not supported.

3.2 Hub/Shroud CSV File

Defines the radius distribution of Hub and Shroud on the meridional plane.

CSV Format:

z, r_hub, r_shroud
0.0, 50.0, 150.0
10.0, 52.0, 148.0
20.0, 55.0, 145.0
...

Requirements:

• First row is header (ignored)
• Z values do not need to be sorted (auto-sorted)
• Z range must cover the blade Z range

CSV Scale Factor:

• Use when CSV units differ from blade units
• Example: If CSV is in meters (m) and blade is in mm -> Scale Factor = 1000

3.3 Flow Direction

Specifies which direction the flow travels along the Z-axis:

+Z Flow Direction:
    LE ------- Blade ------- TE
   Z_min                    Z_max
    <- Flow inlet           Flow outlet ->

-Z Flow Direction:
    TE ------- Blade ------- LE
   Z_min                    Z_max
    <- Flow outlet          Flow inlet ->

4. GUI Usage

4.1 Starting the Program

Run bladextractor.exe.

4.2 Interface Layout

4.3 Basic Workflow

Step 1: Load Blade

1. Click File > Open Blade... (or [...] button in left panel)
2. Select STEP file
3. Blade is displayed in 3D viewer

Step 2: Load Hub/Shroud CSV

1. Click File > Open Hub/Shroud CSV...
2. Select CSV file
3. Hub (blue) and Shroud (red) curves are displayed

Step 3: Set Parameters

CSV Scale:

• If CSV units match blade: 1.0
• If CSV is in meters and blade is in mm: 1000.0

Flow Direction:

• If LE is at Z minimum: +Z (LE at min Z)
• If LE is at Z maximum: -Z (LE at max Z)

Span List:

• Specify Span positions to extract (0.0 = Hub, 1.0 = Shroud)
• Enter value and click Add
• 11 spans button: Auto-add 0.0, 0.1, 0.2, ... 1.0
• Select item and click Remove to delete

Z Range:

• Blade Z range is displayed automatically
• Adjust manually if needed (match with Hub/Shroud curve valid range)

Step 4: Export Profiles

1. Click Export Profiles button
2. Select output folder
3. Enter project name
4. Progress is displayed
5. Completion message shown

4.4 3D View Controls

Mouse:

• Left drag: Rotate
• Middle drag: Pan
• Wheel: Zoom

View Buttons:

4.5 Save/Load Configuration

File > Save Config...: Save current settings to JSON file File > Open Config...: Load JSON configuration file

Saving configuration allows batch processing with the same settings using CLI

5. CLI Usage

5.1 Basic Usage

bladextractor-cli.exe config.json

5.2 JSON Configuration File

{
    "bladeStep": "blade.stp",
    "hubShroudCsv": "flowpath.csv",
    "csvScaleFactor": 1.0,
    "spans": [0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0],
    "flowDirection": "+z",
    "spanBoundaryMargin": 0.01,
    "zRange": {
        "auto": true,
        "marginPercent": 15.0,
        "min": 0.0,
        "max": 100.0
    },
    "output": {
        "directory": "output",
        "projectName": "MyBlade",
        "debugStep": true,
        "saveLog": false
    }
}

5.3 Configuration Options Detail

Input Files

Span Settings

spanBoundaryMargin: Prevents numerical errors at span=0.0 or 1.0. Example: 0.01 means span=0.0 is processed as 0.01, span=1.0 as 0.99

Flow Direction

Z Range

auto=true: Auto-calculate by adding marginPercent to blade Z range auto=false: Specify min/max values directly

Output Settings

5.4 Execution Example

> bladextractor-cli.exe config_rotor.json

[info] BladeXtractor v0.5.0
[info] Config loaded: config_rotor.json
[info]   Blade: NASA_Rotor38.stp
[info]   CSV: FlowPath.csv
[info]   Spans: 11
[info]   Flow direction: +z
[info] Loading blade STEP file...
[info] Loading hub/shroud CSV...
[info] Processing span 0.00...
[info] Processing span 0.10...
...
[info] Profile extraction complete.

6. Output Files

6.1 Output Folder Structure

output/
+-- MyBlade.curve          # Blade profiles (all Spans)
+-- MyBlade_hub.curve      # Hub meridional curve
+-- MyBlade_shroud.curve   # Shroud meridional curve
+-- MyBlade_debug.stp      # Debug STEP (optional)
+-- MyBlade.log            # Execution log (optional)

6.2 Blade Profile (.curve)

## Blade profiles   MyBlade
# Section no.  1
    1.23456789E+01    6.78901234E+01    1.11111111E+02
    1.23556789E+01    6.78801234E+01    1.11121111E+02
    ...
# Section no.  2
    ...

Format:

• Header: ## Blade profiles
• Section header: # Section no.
• Coordinates: X, Y, Z (scientific notation, tab-separated)

Characteristics:

• 301 points per section
• Closed loop: first point = last point
• Point order: TE -> LE -> TE (counter-clockwise)

6.3 Hub/Shroud Curves (.curve)

    5.00000000E+01    1.23456789E+01    0.00000000E+00
    5.20000000E+01    1.23556789E+01    1.00000000E+01
    ...

Format: X, Y, Z coordinates only (no header)

Characteristics:

• Approximately 229 points
• Theta distribution follows blade camber line
• Inlet/Outlet regions maintain TE/LE theta

7. Troubleshooting

7.1 "No intersection found"

Cause: Stream Surface does not intersect with blade

Solutions:

1. Check if Z Range matches blade range
2. Check if CSV Z range covers blade Z range
3. Verify Flow Direction is correct

7.2 Profile Looks Abnormal

Cause: Flow direction or Z range setting error

Solutions:

1. Change Flow Direction (+Z <-> -Z)
2. Manually adjust Z Range
3. Increase spanBoundaryMargin (e.g., 0.01 -> 0.02)

7.3 CSV Load Failure

Cause: CSV format error

Check:

• Column separator is comma (,)
• Header row exists
• Numbers have no unnecessary characters

7.4 Hub/Shroud Curve Looks Wrong

Cause: CSV Scale Factor error

Solutions:

• Check CSV units and blade units
• Adjust Scale Factor

8. Technical Support

• Developer: CLEW, Inc.
• Email: [email protected]
• Website: https://www.clew.tech

9. Disclaimer

License

This software is provided as Freeware and may be used free of charge.

Warranty Disclaimer

THIS SOFTWARE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED. This includes, but is not limited to, the implied warranties of merchantability, fitness for a particular purpose, and non-infringement.

IN NO EVENT SHALL THE DEVELOPERS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THIS SOFTWARE.

Users use this software at their own risk and are solely responsible for all consequences arising from its use.

Trademark Notice

• Ansys and TurboGrid are registered trademarks or trademarks of ANSYS, Inc. or its subsidiaries in the United States and other countries.
• CLEW, Inc. is not affiliated with, sponsored by, endorsed by, or otherwise associated with ANSYS, Inc.
• All other trademarks mentioned in this document are the property of their respective owners.

Appendix A: Example Configuration Files

A.1 NASA Rotor 38

{
    "bladeStep": "NASA_Rotor38_Blade_Surface.stp",
    "hubShroudCsv": "NASA_Stage38_FlowPath.csv",
    "csvScaleFactor": 1.0,
    "spans": [0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, 1.0],
    "flowDirection": "+z",
    "spanBoundaryMargin": 0.01,
    "zRange": {
        "auto": false,
        "marginPercent": 25.0,
        "max": 71.8,
        "min": -10.7
    },
    "output": {
        "directory": "output",
        "projectName": "Rotor38",
        "debugStep": true,
        "saveLog": true
    }
}

A.2 Simple Configuration (Auto Z Range)

{
    "bladeStep": "my_blade.stp",
    "hubShroudCsv": "flowpath.csv",
    "spans": [0.0, 0.5, 1.0],
    "output": {
        "projectName": "MyBlade"
    }
}