The Meridional Control Curves are used to control the meridional interpolation grid. This grid is used to create layers and control spanwise interpolation of the other Working Views.

BladeGen now allows three modes of operation for Meridional Control Curves, as shown below. This enables the specification of geometry that was previously troublesome or even impossible. All three modes use the Inlet, Leading Edge, Trailing Edge, and Outlet Curves and add control curves at break points in the hub and shroud curves.

Minimal - The Minimal mode does not add additional control curves. It reproduces the interpolation grid of previous versions when the "Additional Control Curve" option was not enabled.

Normal - The Normal mode adds two predefined control curves at 35% and 65% of the blade’s meridional length. It reproduces the interpolation grid of previous versions when the "Additional Control Curve" option was enabled and is the default mode.

User-Defined - The User-Defined mode allows the user to add arbitrary control curves. Curves can be added at a mouse click or the user can request that a location be suggested when to improve the meridional interpolation. See the Meridional View Popup Menu for information on the additional menu commands available for this mode.

When in User Defined mode for Meridional Control Curves, the control curves are displayed as dashed lines (they are not displayed in other modes). In addition, the Meridional Control Curve sub-menu commands are enabled, which allow the following tasks to be performed.

This dialog provides access to the layers of the model. This dialog is re-used to specify which layers are to be used for the Angle, Thickness, Prs/Sct, and Output definition of the model, one at a time.

Also See:

Layer Dialog

This dialog allows the user to select a layer’s type and set its parameters. This dialog is used for both initial setup of a layer and modification of a layers properties.

Select a tab to specify the layer type.

The Span tab selects the Span-wise Type and provides access to the parameters. Enter the location as a span fraction (normally 0 to 1, but values of -0.5 to 1.5 are accepted for Design Layers).

The Hub Gap tab selects the Hub Gap Type and provides access to the parameters. Enter a leading and trailing edge gap (in model units) into the spaces provided. The layer will be located using an offset vector normal to the hub. The magnitude of this offset vector at each point on the hub curve is determined by linear interpolation between the gap values entered for the leading and trailing edges. A positive value for either the leading or trailing edge gap implies a direction that is ’into the flow path’ (or towards the Shroud) for that gap.

The Shr Gap tab selects the Shroud Gap Type and provides access to the parameters. Enter a leading and trailing edge gap (in model units) into the spaces provided. The layer will be located using an offset vector normal to the Shroud. The magnitude of this offset vector at each point on the shroud curve is determined by linear interpolation between the gap values entered for the leading and trailing edges. A positive value for either the leading or trailing edge gap implies a direction that is ’into the flow path’ (or towards the Hub) for that gap.

The Data tab selects the Data (User-Defined) Type and provides access to the parameters. Enter the approximate location as a span fraction (normally 0 to 1, but -0.5 to 1.5 for Design Layers). Once the layer has been created, it can be redefined in the Meridional View interactively using the same tools provided for other curves.

The Hub Off tab selects the Hub Offset Type and provides access to the parameters. This option creates a layer whose location from the Hub is defined by a constant offset vector. The radial and axial components of this vector are entered in the controls provided. A positive value for the radial or axial component implies a direction that is ’into the flow path’ (or towards the Shroud) for that component.

The Shr Off tab selects the Shroud Offset Type and provides access to the parameters. This option creates a layer whose location from the Shroud is defined by a constant offset vector. The radial and axial components of this vector are entered in the controls provided. A positive value for the radial or axial component implies a direction that is ’into the flow path’ (or towards the Hub) for that component.

The points that make up this segment type are joined by straight lines.

This segment type is often a good choice for the thickness curve and is also used as the default type when importing data into the Meridional View. It is not recommended for most other applications.

Please note that the segment type does not use the exact shape. Instead, a constant number of equally spaced points are used to create a spline that is used for interpolation. If the discontinuities are desired, the user should create break points.

This segment type is defined by a set of piecewise curves connecting the data points. These curves use an interpolation formula that is continuous through the second derivative. This derivative continuity is preserved at the junctions between piecewise curves, resulting in a smooth total curve that passes through all of the points.

This segment type forms the basis for many of the underlying operations within BladeGen, especially operations involving point conversions. It replaces the Lagrangian Spline curve used in previous versions.

This type of curve is defined by control points. It passes through the end points and is controlled by a set of intermediate points. The curve does not necessarily pass through the intermediate points. However, one of the properties of a Bezier curve is that the first point in from each end determines the angle at the end points.

Bezier curves are recommended for the design of a blade in the Meridional and Prs/Sct views, because they are both smooth in shape, and resistant to local curve distortions resulting from manipulation of the control points.

This segment type is defined by a polynomial curve, the coefficients of which are determined from a least squares fit to the data points in the segment. In general, this type of curve will not pass through any of the data points. However, BladeGen adds constraints to force the curve to pass through the end points. The order of the polynomial is specified by the user.

This type of curve is best suited to use where the data is "noisy" and some smoothing is required. It is the default curve type for imported Angle View curves.

This segment consists of a 3-point circular arc. The arc is defined by the end points and either a fixed radius or a fixed angle. Editing of the middle point is performed using an Arc Parameters Dialog, created specifically for the task. A popup menu command can be used to flip the arc if required.

This type of segment is best suited for use in the Meridional View, where it is commonly used to define a leading or trailing edge. It is not available in the Angle and Thickness Views.

To switch to a different segment type:

Note that this is different than performing the point conversion operations described above, because the shape of the original curve is not necessarily preserved. The new curve type uses the original set of points directly, even though it may interpret those points differently than the old curve type.

For example, when switching from a Bezier Curve to a Cubic Spline Curve, the new spline curve is simply fit through the original Bezier control points. This is different than using the Convert Points to | Spline Curve Points... function where BladeGen would first generate new points on the Bezier Curve and then fit a spline through them.

The General Distribution is the default Spanwise Distribution type. The parameter of interest (angle or thickness) is defined by curves on defining layers that use various meridional coordinates from those layers. Since these layers may have arbitrary shapes that don’t necessarily correspond to true streamlines, BladeGen must first convert their coordinates to "true" meridional coordinates (consistent with the meridional interpolation grid) before using them to compute the parameters to generate a blade.

The Ruled Element Spanwise Distribution type is only available in the Angle View.

In a ruled element blade, the angular location is defined by a straight line drawn in 3D space between points at the span location on the hub and shroud. The hub and shroud curves are the principal curves. They control the generation of all other defining curves. Thus, the hub and shroud curves are the only curves that the user can modify in the Spanwise Distribution type.

When one of the defining curves is updated from the hub curve, it obtains its location by the intersection of the surface of revolution generated using the meridional streamline and the lines drawn between corresponding pairs of points on the hub and shroud. Once this update occurs, a conversion is made to "true" meridional coordinates using the same method as in the general Spanwise Distribution type.

It is important to specify enough defining layers to adequately describe the geometry of interest. In most cases, 5 layers are sufficient.

In an axial element blade, the parameter of interest (angle or thickness) depends exclusively on radial position (R) at each span location. The hub curve is the principal curve; it controls the curves for all of the other defining layers. Thus, the hub curve is the only curve that the user can modify in this Spanwise Distribution type. When a defining layer curve is updated from the hub curve, it obtains its parameter (angle or thickness) at a given meridional position by using an axial projection from the hub curve. Once this update occurs, a conversion is made to "true" meridional coordinates using the same method as in the general Spanwise Distribution type.

When using axial element blades, it is important to specify enough defining layers to adequately describe the geometry of interest. In most cases, 5 layers are sufficient.

When this distribution type is used in the Thickness View, there is a menu command in the popup menu to specify a taper angle. The taper angle, which normally defaults to zero, is limited to guarantee a minimum thickness of 10% of the specified value.

In a radial element blade, the parameter of interest (angle or thickness) depends exclusively on axial position (z) at each span location. The hub curve is the principal curve; It controls the curves for all of the other defining layers. Thus, the hub curve is the only curve that the user can modify in this Spanwise Distribution type. When a defining layer curve is updated from the hub curve, it obtains its parameter (angle or thickness) at a given meridional position by using a radial projection from the hub curve. Once this update occurs, a conversion is made to "true" meridional coordinates using the same method as in the general Spanwise Distribution type.

When using radial element blades, it is important to specify enough defining layers to adequately describe the geometry of interest. In most cases, 5 layers are sufficient.

New - Create a new document.

Open - Open an existing document. The filename extension is used to determine the type of window in which it should be displayed.

Close - Close the active document (window).

Save - Save the active document. The Save command saves the document in the active window to disk. If the document is unnamed, the Save File As dialog box is displayed so you can name the file, and choose where it is to be saved.

Save As... - Save the active document with a new name. The Save As... command allows the user to save a document under a new name, or in a new location on disk. The command displays the Save File As dialog box. The user can enter the new file name, including the drive and directory. All windows containing this file are updated with the new name. If an existing file name is chosen, the user will be asked for confirmation to overwrite the file.

Compare... - Compare the current geometry to a saved blade geometry. The Compare... command displays the file selected in the File Open Dialog in the background (gray), behind the current model, for comparison. This allows the user to save a version of a model and then modify the current version with a visual comparison to the original model.

Export Submenu - See Export Submenu.

Print... - Print the active document. The Print... command prints the contents of the active window (or view). Use File | Print Preview... to see how the document will be laid out on printer pages. Use File | Print Setup... to select a printer, and to set printer options. Use File | Export | Report... to output a detailed report of a BladeGen model.

Print Preview - Display full pages. The Print Preview command opens a special window that shows how the active document will appear when printed. The preview window shows one or two pages of the active document as they would look when printed.

Print Setup... - Change the printer and printing options. The Print Setup... command displays the Printer Setup dialog box which allows you to select and configure the printer to be used to print documents in the application.

Preferences... - Display the User Preferences Dialog to allow the user to select some of the program defaults.

Recent File - Open a document from a selection of recently opened files.

Exit - Quits the application; prompts to save documents. If you have modified documents without saving, you will be prompted to save before exiting.

Toolbars Submenu - See Toolbars Submenu.

Arrange Views Submenu - See Arrange Views Submenu.

New Auxiliary View (B2B) - Display a new auxiliary Blade-to-Blade View of the current layer.

Auxiliary View Content Submenu - See Auxiliary View Content Submenu.

Ang/Thk Plot Horizontal Axis Submenu - See Ang/Thk Plot Horizontal Axis Submenu.

Layers for Plots of ’All Layers’ Submenu - See Layers for Plots of ’All Layers’ Submenu.

New Window - Open another window for the active document.

Cascade - Arrange windows so they overlap. The Cascade command arranges all document windows from the top-left position of the application’s main window so that the title bar of each is visible.

Tile Horizontal - Arrange all document windows horizontally in a non-overlapping pattern.

Tile Vertical - Arrange all document windows vertically in a non-overlapping pattern.

Arrange Icons - Arrange icons at the bottom of the window.

The Blade-to-Blade view, shown below, combines the meridional, angular, and thickness descriptions of the blade along a streamline (called a layer). The blade is displayed as a function of the distance along the streamline in the meridional view and its angular position using one of three Coordinate Systems (Coordinate Systems ).

This view is displayed using either the View | Auxiliary View Content | Blade-to-Blade View menu command or the   toolbar button (located by default on the right edge of the main window). See Blade-To-Blade View Popup Menu for details of the options and functions available in this view.

Figure 9.35: Blade-to-Blade View

The Blade-to-Blade view displays the shape of the blade on a surface of rotation that may or may not be cylindrical or planar. Therefore, a conformal coordinate system must be used to transform the 3D data into a 2D view. Several systems have been developed over the years, each with its strengths and weaknesses, as detailed below. The selection of one system over another is left to the user.

 

9.1.5.7.2.2.1. M-Prime vs. Theta

The M-Prime vs. Theta conformal coordinate system presents all of the blades in an angular shape preserving view, as shown below. However, because of the normalizing of the meridional distance with radius, the thickness of the blade is distorted.

Figure 9.36: M-Prime vs. Theta System

 

9.1.5.7.2.2.2. M vs. R*Theta

The M vs. R*Theta conformal coordinate system preserves the thickness of the blade, as shown below. However, the angular shapes of all blades are distorted.

Figure 9.37: M vs. R*Theta

 

9.1.5.7.2.2.3. M vs. Theta-Prime

The M vs. Theta-Prime conformal coordinate system is the only system that preserves both the angular shape and the thickness of the current blade, as shown below. However, it distorts the angular shape of all other blades.

Figure 9.38: M vs. Theta-Prime System

The Display Group Control... menu command controls which items are displayed in the 3D view. This command will display the Display Group Control Dialog shown below. Placing a checkmark in the box to the left of an item will cause that item to be displayed.

Figure 9.40: Display Group Control Dialog

Double clicking on an item in the Display Group Control Dialog will invoke a Display Group Property Dialog for that item, as shown below. This dialog allows the user to set the following display attributes for the selected item:

Figure 9.41: Display Group Property Dialog

Objects may be displayed in three different ways, as shown below. The desired view type can be selected in the view’s popup menu (using the Surface Display command) or by pressing a toolbar button.

In a BladeGen model of a cyclically symmetric blade system, only the geometry between a single set of periodic boundaries is stored. This geometry typically consists of a main blade and any associated splitters. Even though BladeGen does not store redundant geometry, it allows the user to visualize the entire blade system by using replicates. The table below lists the available commands for viewing replicates. These commands are accessed by using the Replication option in the view’s popup menu or by pressing the appropriate toolbar button.

Clipping planes allow the user to explore the inside of the model by clipping away parts of the view. There are six clipping planes available. To activate the clipping planes, use the Clip command in the view’s popup menu or the toolbar buttons. These provide options to toggle each plane on or off, select which plane to move with the mouse wheel, and open the Clipping Plane Property Dialog. With Windows NT and later, the selected clipping plane can be moved by depressing the mouse wheel and then rotating it.

Figure 9.42: Clipping Plane Property Dialog

Each clipping plane can be customized with the Clipping Plane Property Dialog, shown above, which is accessed using the Clip | Setup menu command or the   toolbar button. This dialog allows the user to specify the clipping direction (either by setting the components of a vector normal to the plane or by using one of the predefined direction options). It also allows the user to set the initial plane location, either by specifying the coordinates of a point on the plane or by setting a minimum distance from the origin. The clipping plane can also be activated and deactivated in this dialog.

The clipping planes are initially defined as shown below.

The viewpoint controls are provided to manipulate the orientation and position of the 3D View. A combination of keyboard shortcuts, menu commands, or mouse buttons are available. In addition, some of the menu commands are duplicated on the toolbars.

The coordinates in the above table refer to screen coordinates where positive X is to the right, positive Y is upwards and positive Z is out of the screen. Positive rotation about a given axis is defined as counterclockwise when looking down that axis from its positive direction.

The 3D view allows up to eight lighting sources. The user may override the default parameters for these sources by using the Light Control Dialog shown below. This dialog is displayed by using the Light Control... popup menu command.

Figure 9.43: Light Control Dialog

In the 3D view, the material properties control the display of the shaded surface. The Material Control Dialog, shown below, allows the user to set material properties (such as color and shininess) for these surfaces. The Material Control Dialog is displayed by using either the Front Material Def... or the Back Material Def... popup menu command.

BladeGen allows the user to specify different lighting properties on the front and back sides of a surface. (The front side is typically the side exposed to the flow path.) Use the Shaded Material Mode | Front/Back Unique popup menu command to select this option.

Figure 9.44: Material Control Dialog

The Shaded Material Mode | Front/Back Same popup menu command forces both the front and back material properties to be the same. In this case, the Back Material Def... popup menu command will be disabled and both sides will use the properties of the front material.

The animation capability of the 3D view allows the user to see the model rotating on the screen. To animate the model, select the Animate popup menu command from the view’s popup menu. The user can customize the way the animation is performed by using the Animation Dialog shown below. This dialog is displayed using the Animation Setup... popup menu command. The degrees of rotation per animation frame can be entered in either model or screen coordinates. The speed at which the frames will be shown can also be entered. However, the speed of the animation will ultimately be limited by the speed of the CPU and graphics card.

Figure 9.45: Animation Dialog

Blade Submenu - See Blade Submenu.

New Auxiliary View (B2B) - Display a new auxiliary Blade-to-Blade View of the current layer.

Auxiliary View Content Submenu - See Auxiliary View Content Submenu.

Theta (Location) Angle - Display a color contour plot of blade angle (Theta) in the Meridional View using the current interpolation grid density.

Beta (Blade) Angle - Display a color contour plot of blade angle (Beta) in the Meridional View using the current interpolation grid density.

Blade Lean Angle - Display a color contour plot of the blade lean angle in the Meridional View using the current interpolation grid density.

Normal Thickness - Display a color contour plot of blade thickness in the Meridional View using the current interpolation grid density.

Modified Thickness - Plot Modified (with Over/Under-Filing) Thickness Contours in the Meridional View. The Modified Thickness command selects the ’Enhanced Thickness’ data for display in the Contour View. The ’Enhanced Thickness’ is the blade thickness with any over/under-filing applied (but not the ellipse or cut-off).

Data Grid Density Submenu - Set the density of the grid used to interpolate contour data. When a contour plot is generated, blade data for the selected data type is extracted for each point in the interpolation grid. Contour boundaries are then generated by interpolating between the values at these data points.

Show Contour Lines - Show solid lines between contour levels.

Show Data Points - Show the points at which blade data is extracted for contour plotting.

Show Grid - Display the interpolation grid used to extract blade data for contour plotting. Each intersection in the grid represents a point at which blade data is generated.

Copy View Image/Data to Clipboard - Copy the Current View’s Image and/or Data to the Clipboard (in text, bitmap, or metafile formats). This allows transfer of data to reports, spreadsheets, and presentations for documentation of the blade design.

Zoom Fit - Zoom to fit the data within the current view.

Main Blade - Select the main blade for display and modification. The data for this blade will then be available for editing.

Splitter 1 - Select splitter #1 for display and modification. The data for this blade will then be available for editing.

Layer Submenu - The Above command changes the displayed layer to the next layer above (by span). The Below command changes the displayed layer to the next layer below (by span). These commands allow rapid changes in the displayed layer, including layers which are not defining layers.

New Auxiliary View (B2B) - Display a new auxiliary Blade-to-Blade View of the current layer.

Auxiliary View Content Submenu - See Auxiliary View Content Submenu.

Ang/Thk Plot Horizontal Axis Submenu - See Ang/Thk Plot Horizontal Axis Submenu.

Layers for Plots of ’All Layers’ Submenu - See Layers for Plots of ’All Layers’ Submenu.

Show Legend - Toggle the display of the legend on/off.

Show Points - Toggle the display of the data points on/off.

Show Comparison Curves - Toggle the display of the data curves from the comparison model on/off. These curves are darker in color and use a smaller marker to differentiate them from the other curves.

Number of Points... - Displays a dialog to allow the user to select the number of points displayed in the curves.

Swap Axes - Swap the horizontal and vertical axes of the selected graph.

Proportional Axes - Toggle the proportionality setting of the graph axes on/off.

Flip X Axis Direction - Flip the direction of the X Axis. When the Axis is flipped, the positive direction is reversed.

Flip Y Axis Direction - Flip the direction of the Y Axis. When the Axis is flipped, the positive direction is reversed.

Log X Scale - Toggle between Linear and Log (base 10) scaling on the horizontal axis.

Log Y Scale - Toggle between Linear and Log (base 10) scaling on the vertical axis.

Save Graph Data... - Save the data from the graph to the specified file. The Save Graph Data... command displays the File Save Dialog and saves the data in the current graph in the specified file. The file is comma delimited and can be read into Microsoft Excel(tm) or similar software.

Copy View Image/Data to Clipboard - Copy the Current View’s Image and/or Data to the Clipboard (in text, bitmap, or metafile formats). This allows transfer of data to reports, spreadsheets, and presentations for documentation of the blade design.

Zoom Fit - Zoom to fit the data within the current view.

BladeGen displays a number of data sets in the Graph View. The table below lists the current data sets.