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RSPINR |
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RSPINR |
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»Click here to display Table of Contents«
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RSPINR |
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RSPINR |
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Bulk Data Entry
RSPINR – Relative Rotor Spin Rates (Rotor Dynamics)
This entry defines the relative spin rates between rotors during a rotor dynamic analysis in Modal Complex Eigenvalue or Frequency Response solution sequences.
Format
(1) |
(2) |
(3) |
(4) |
(5) |
(6) |
(7) |
(8) |
(9) |
(10) |
RSPINR |
ROTORID |
GRIDA |
GRIDB |
SPDUNIT |
SPTID |
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GR |
ALPHAR1 |
ALPHAR2 |
HYBRID |
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Argument |
Options |
Description |
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ROTORID |
<Integer > 0> No default |
setid |
Rotor identification number. |
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GRIDA |
<Integer > 0> No default |
Identifies a grid on the Rotor Line Model. GRIDA and GRIDB define the positive rotor spin direction. The vector connecting GRIDA and GRIDB is the positive direction vector. The rotor axis is defined using the ROTORG bulk data entry and the two grids (GRIDA, GRIDB) are also specified on the ROTORG bulk data entry. |
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GRIDB |
<Integer > 0> No default |
Identifies a grid on the Rotor Line Model. GRIDA and GRIDB define the positive rotor spin direction. The vector connecting GRIDA and GRIDB is the positive direction vector. The rotor axis is defined using the ROTORG bulk data entry and the two grids (GRIDA and GRIDB) are also specified on the ROTORG bulk data entry. |
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SPDUNIT |
<RPM, FREQ> No default |
RPM: |
Specifies that the relative spin rates are input in Revolutions Per Minute. |
FREQ: |
Specifies that the relative spin rates are input in revolutions (cycles) per unit time. |
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SPTID |
<Integer > 0/Real> No default |
<Integer > 0> |
If an integer value (must be greater than 0) is input, it references a DDVAL bulk data entry that specifies the relative rotor spin rates (see comment 3). |
<Real> |
If a real number is input, the value is considered constant. |
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GR |
<Real> Default = 0.0 |
Rotor Structural Damping Factor (see comments 4 and 6). |
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ALPHAR1 |
<Real> Default = 0.0 |
Scale factor applied to the rotor mass matrix for Rayleigh Damping (see comments 5 and 6). |
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ALPHAR2 |
<Real> Default = 0.0 |
Scale factor applied to the rotor stiffness matrix for Rayleigh Damping (see comments 5 and 6). |
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HYBRID |
<Integer > 0> Default = 0 |
Hybrid damping. References the identification number of a HYBDAMP entry for hybrid damping specification. Can be used to specify frequency-dependent hybrid damping value for each rotor (ROTORID) (see comment 6). |
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| 1. | A RSPINR entry must exist for each rotor line model defined using the ROTORG bulk data entry. |
| 2. | GRIDA and GRIDB define the positive rotor spin direction. The vector connecting GRIDA and GRIDB is the positive direction vector. The rotor axis is defined using the ROTORG bulk data entry and the two grids (GRIDA, GRIDB) are also specified on the ROTORG bulk data entry. |
| 3. | An integer or a real number can be input in the SPTID field. If SPTID is an integer, it references a DDVAL bulk data entry that specifies the relative rotor spin rates. Each rotor must be assigned the same number of spin rates. To determine relative spin rates, the table entries which contain the sequence of spin rates are correlated. The i’th entry for each rotor corresponds to the relative spin rates between rotors at RPMi/FREQi. The spin rates for the reference rotor must be specified in ascending or descending order. |
| 4. | Rotor structural damping factor (GR) can be incorporated as either equivalent viscous damping or structural damping depending on the solution sequence. |
Or,
Where, WR3 is a parameter defined by PARAM, WR3 and GR is defined as a field on the RSPINR bulk data entry.
The selection depends on the following factors:
| • | Modal frequency response or Complex eigenvalue analysis |
| • | Synchronous or Asynchronous solutions |
| • | Value of PARAM, GYROAVG |
| 5. | The Rayleigh damping value for the rotor is calculated as: |
| 6. | The damping and circulation terms added to the corresponding analysis equations are listed in the table below. Refer to Rotor Dynamics in the User's Guide for detailed information. |
Solution Sequence - Analysis |
Damping |
Circulation |
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Frequency Response (ASYNC) |
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Frequency Response |
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Frequency Response (SYNC) |
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Frequency Response |
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Complex Eigenvalue (ASYNC) |
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Complex Eigenvalue (SYNC) |
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Where,
is the rotor viscous damping
is the rotator hybrid viscous damping
is the rotor mass
is the rotor stiffness
is the rotor material damping
is the rotor hybrid material damping
is the circulation, due to rotor viscous damping
is the circulation, due to rotor hybrid viscous damping
is the circulation, due to rotor mass
is the circulation, due to rotor structural stiffness
is the circulation, due to rotor material damping
is the circulation, due to rotor hybrid material damping
and 
are used to define the Rayleigh viscous damping, as follows:
WR3, WR4 and WRH are defined by the parameters PARAM, WR3, PARAM, WR4, and PARAM, WRH. These parameters allow you to bypass frequency-dependent looping by specifying the equivalent “average” excitation frequencies, when PARAM, GYROAVG, -1 is specified.
| 7. | Rotor damping is cumulative and caution should be exercised when multiple damping effects are assigned. |
See Also:
