The Basic Settings tab is used to define the fundamental properties of a mode shape. It is accessible by creating a new mode shape or by editing a mode shape listed in the tree view.
The Use Profile Data check box appears only if there are user functions already defined by the initialization of profile data (Tools > Initialize Profile Data). If Use Profile Data is selected, you can select a profile from the drop-down, and then click Generate Values to automatically configure Mode Shape Settings.
The Mode Shape Settings allow you to set a mode shape, frequency, and phase offset.
The mode shape displacement vector components can be specified as:
Cartesian Components
Provide X, Y, and Z components of the displacement as well as a Scaling factor with which to multiply the displacement components in order to obtain the intended maximum displacement.
Normalized Cartesian Components
Provide X, Y, and Z components of the displacement and specify directly the maximum Amplitude of the displacement.
Complex Cartesian Components
Provide X, Y, and Z components for the real and imaginary parts of the displacement as well as a Scaling factor with which to multiply the displacement components in order to obtain the intended maximum displacement.
Normalized Complex Cartesian Components
Provide X, Y, and Z unit-normalized components for the real and imaginary parts of the displacement and specify directly the maximum Amplitude of the displacement.
For all of the above options, you need to provide:
The Structural Damping value is a modal coefficient that describes a dissipation property related to the dynamic behavior of the mode shape.
The Modal Mass value is a modal coefficient that describes an inertial property related to the dynamic behavior of the mode shape.
The vibration Frequency
A Phase Angle that offsets the displacement in time.
The following Phase Angle options are available:
Value
You can use this option to set a Phase Angle to offset the mode shape displacement.
Nodal Diameter (Phase Angle Multiplier)
This option is only available for Transient Blade Row simulations.
The corresponding settings are:
Nodal Diameter Mag.: the magnitude of the nodal diameter
Traveling Wave Dir.: the traveling wave direction:
ForwardorBackward.By default, the direction considered to be
Forwardis:For a model that has a rotating component: the direction of machine rotation
For a model that has only stationary components (for example, a model of a stand-alone stator): the direction of increasing sector tag number
A forward traveling wave is illustrated in Case 3: Blade Flutter in the CFX-Solver Modeling Guide.
Passage Number
Interblade Phase Angle
This option is only available for Transient Blade Row simulations.
The corresponding settings are:
Phase Angle
Passage Number
From Profile (available when Profile Mode Shapes > Use Profile Data is selected)
When using a profile that has been expanded using CFX-Pre’s profile expansion tool, the Nodal Diameter is read directly from the Harmonic Index entry in the original passage mode shape profile. Similar to the
Nodal Diameteroption, you can select the Traveling Wave Direction (ForwardorBackward). For details, see Case 3: Blade Flutter in the CFX-Solver Modeling Guide.