### 10.2.6. Section Definition and Stacking Views

When using Airfoil design mode (enabled via the Blade Design Mode setting of the blade object) the Section Definition and Section Stacking views are available to enable you to see and modify the airfoil shapes and their theta distribution across (either spanwise or user-defined) layers. These views have behavior similar to the Angle and Thickness views (see Angle and Thickness Views). Both views present the data for the active Blade Section sub-feature.

If the Blade feature or any of its parent features have been modified, the curves shown in the Section Definition/Stacking views, when displayed under the Blade feature, are updated when the model is regenerated.

The following topics are discussed:

- Section Definition View
- Section Stacking View

#### 10.2.6.1. Section Definition View

The Section Definition view displays, and enables you to adjust, the airfoil shape for each Blade Section sub-feature.

To show the Section Definition view:

1. Select the Blade Section sub-feature (under the Blade feature) for which you want the Section Definition view.

2. If you do not see the Section Definition view, click Show/Hide section shape .

The blade section shape is displayed in the Section View (Figure 10.2: Blade Section View). The blade section shape can be modified by changing the section dimensions in the details view, or by dragging the Bezier curve control points in the Section View. The Section View also displays the:

- pitch line

- adjacent blade position

- specified throat line

- calculated throat (throat with the minimum throat length) and its midpoint

- airfoil centroid

- both ellipses, their axes and centers

- stagger line

Any of the defining dimensions can be parameterized by clicking in the check box next to the dimension.

Figure 10.2: Blade Section View

Within the Section Definition view, you can:

- Access a shortcut menu by right-clicking the mouse.

- Drag the Bezier curve control points defining the pressure and suction side edges of the airfoil shape (click a control point and drag it with the mouse).

- Insert a point on a Bezier curve (right-click in view to insert the new point).

- Delete a point from a Bezier curve (right-click the point to be deleted; only interior points may be deleted).

- Set control point coordinates (double-click a control point and edit the coordinate values in a dialog box).

- Reset the airfoil input parameters and control points to their original values (context menu)

- Toggle the display of the blade pitch spacing line (context menu)

- Toggle the display of the specified throat width (context menu)

- Toggle the display of the calculated throat width and its midpoint (context menu)

- Toggle the display of the airfoil centroid location (context menu)

- Toggle the display of the LE ellipse (context menu)

- Toggle the display of the TE ellipse (context menu)

- Toggle the display of the stagger line (context menu)

- Toggle the display of a point on the airfoil surface that corresponds to the point currently selected in the curvature view (context menu)

- Pan the view (right-click and drag).

- Zoom in and out (middle-click and drag).

- Zoom to fit the view (context menu)

- Zoom in via a zoom box (hold the Alt key and click and drag from the top-left corner to the bottom-right corner of a rectangular region; drag in the opposite direction to re-fit the view).

Note: Toggling the display options will make them take effect for the remainder of the session, but not from session to session.

You can see the curvature of an airfoil section via the Curvature view. For details, see Curvature View.

#### 10.2.6.2. Section Stacking View

The Section Stacking view displays, and enables you to adjust, the theta-versus-span distribution of blade section shapes (airfoils).

To show the Section Stacking view:

1. Select the blade for which you want the Section Stacking view.

2. If you do not see the Section Stacking view, click Show/Hide Stacking Pane .

The individual airfoil sections are stacked in 3D space by the meridional position of the section and by the Theta position of the section. Each section has a reference location that defines the stacking point. The Section Reference Location may be one of the following:

- Section Origin

- Airfoil Centroid

- LE Camberline Point

- TE Camberline Point

- Chord Midpoint

- Throat Midpoint

The meridional position is defined by the Meridional Stacking Method, for which there is currently one available option:

- LE/TE Contours – the meridional extent of each airfoil section is determined by the intersections of the LE and TE contours with the section-defining layer contour. In this way, you can control the meridional extent of the blade by adjusting the LE/TE contours. In this mode, the section reference location is only used for Theta positioning of the blade section.

The absolute Theta position of each section (at the Section Reference Location) is defined by a stacking curve. The stacking curve specifies how the Theta coordinate of the Section Reference Location varies with non-dimensional span location. You can control the shape of the stacking curve in the Section Stacking Graph by dragging the curve points, insert/deleting points, or by changing the curve type.

Figure 10.3: Section Stacking Graph

For example, if you wanted to stack the sections in a straight radial line based on the airfoil centroids, you would set Section Reference Location to `Airfoil Centroid` and set the section stacking graph to have the same angle for all span values.

Within the Section Stacking view, you can:

- Access a shortcut menu by right-clicking the mouse.

- Drag (using the mouse) the control points defining the stacking curve.

- Convert the selected curve segment to a Bezier or spline curve of the specified order (context menu).

- Change the curve type: Bezier, cubic spline, piecewise-linear (context menu).

- Insert a point on the stacking curve (right-click in view to insert the new point).

- Delete a point from the stacking curve (right-click the point to be deleted).

- Set control point coordinates (double-click a control point and edit the coordinate values in a dialog box).

- Pan the view (right-click and drag).

- Zoom in and out (middle-click and drag).

- Zoom to fit the view (context menu)

- Zoom in via a zoom box (hold the Alt key and click and drag from the top-left corner to the bottom-right corner of a rectangular region; drag in the opposite direction to re-fit the view).

- Read stacking data points from a file or save points to a file (context menu).

- Assign parameters to the stacking curve control points - X, Y values (context menu)

  The technique for setting input parameters for control points in the Stacking view is the same as that for the control points in the Angle and Thickness views. This technique is described in Camberline/Thickness Definition Sub-feature.

Note: The lean angle is defined as atan(R * dTheta / dSpan) for any point on the stacking curve. A purely radial stacking curve would have zero lean angle.

Note: Toggling the display options will make them take effect for the remainder of the session, but not from session to session.

Note: Some context menu commands are not available whenever at least one control point is eligible to be selected as an input parameter due to having been processed by the Use as Input Parameter command.

Release 18.2 - © ANSYS, Inc. All rights reserved.