An MSC.Nastran Primer for Rotordynamics

Chuck LawrenceNASA Glenn

Cleveland, Ohio

MSC.Nastran Rotordynamics Damage Resulting from Blade-Out

MSC.Nastran Rotordynamics Types of Analyses

Engine performance• critical speeds• whirl • forced response (unbalance, cabin noise) • damping• Static Analysis (external loads, maneuver loads)

Transient blade off• structural system response• windmilling

MSC.Nastran Rotordynamics Typical Structural ModelEngine Static Structure

MSC.Nastran Rotordynamics Background

• 1998 Meeting with engine and airframe manufacturers and MSC.Software

• All manufacturers performing similar typesof analysis

• All manufacturers using similar, but self developed and maintained, software tools

• Common need to develop standardized analysis tools

MSC.Nastran Rotordynamics Participants

• Boeing Commercial Airplane Group• Pratt & Whitney • General Electric Aircraft Engines • Rolls Royce • Ohio Aerospace Institute • MSC.Software• NASA

• Form Working Group• Define General Program Plan, Benefits and

Advocacy Package• Secure Funding• Develop “Boeing” Document• Bring MSC.Software Aboard• Develop Software Requirements Document• Develop Software• Validate Software• Phase II

MSC.Nastran Rotordynamics Process

MSC.Nastran Rotordynamics Unique Features

• General Finite ElementCapabilities

• Component Substructuring• Condensation of 3D Rotors• Rotor Damping• Non-Constant Rotor Speed• Complex Mass Unbalance• Fan-Case Interactions• Multi-Spool Rotors• Maneuver Loads• Parametric Excitations

Primer Table on ContentsI. Single Spool Rotor

1. Geometry2. Gravity Loads3. Maneuver Loads4. Transient Unbalance Response5. Synchronous Vibration (Critical Speeds)6. Asynchronous Vibration (Whirl Analysis)7. Comparison of Damping Models

II. Dual Spool Rotor1. Geometry 2. Synchronous Vibration (Critical Speeds) 3. Asynchronous Vibration (Whirl Analysis)4. Transient Unbalance Response

III. Squeeze Film DamperIV. Three Dimensional Model Reduction

Single Spool Rotor With Rotor and Support Damping

XZ

YSupportSprings

Rigid ShaftDisk

Unbalance Load

101 102 103

(104) (105)

SupportDamper

RotationVector

RotorDamper

1 $2 $ ROTOR DYNAMICS SAMPLE PROBLEM3 $ SINGLE ROTOR, UNBALANCE LOAD4 $5 6 ID SAMPLE ROTOR7 SOL 1298 DIAG 5, 8, 569 CEND

10

12 TSTEP= 10013 SET 500 = 10214 DISPLACEMENT(PUNCH) = 50015 16 BEGIN BULK17

20 TSTEPNL, 100, 40000, 1.E-3, 2021 22 $23 $ ROTOR 124 $

30 31 GRID, 101, , 0., 0., 0.32 GRID, 102, , 1., 0., 0., , 1433 GRID, 103, , 2., 0., 0.34 GRID, 104, , 0., 0., 0.35 GRID, 105, , 2., 0., 0.36 37 RBE2, 1001, 102, 123456, 101, 10338 RBE2, 1002, 101, 123456, 10439 RBE2, 1003, 103, 123456, 10540 41 CONM2, 1004, 102, , 50.,42 , 5.0, , 15.0, , , 15.043 44 CELAS1, 1005, 1000, 104, 245 CELAS1, 1006, 1000, 104, 346 CELAS1, 1007, 1000, 105, 247 CELAS1, 1008, 1000, 105, 348 PELAS, 1000, 1.0E+5, 0.049 50 ENDDATA

Single Spool Rotor Transient Analysis

11 RGYRO= 111

18 UNBALNC, 111, 100.0, 102, 0., 1., 0.,19 , 1.0, 0.0, 0.0, 0.0, , NONE

26 ROTORG 10 101 THRU 10327 RSPINT, 10, 101, 102, , RPM, 10028 TABLED1, 10029 , 0.0, 800., 100.0, 800., ENDT

Single Spool RotorTransient Response

Single Spool Rotor - Critical Speeds

1 $2 $ ROTOR DYNAMICS SAMPLE PROBLEM3 $ SINGLE ROTOR, CRITICAL SPEEDS4 $5 6 ID SAMPLE ROTOR7 SOL 1078 DIAG 5, 8, 569 CEND

10

12 DISP = ALL13 CMETHOD = 10014 15 BEGIN BULK16 17 EIGC, 100, CLAN,18 , 0., 0., , , , , 10

20 21 $22 $ ROTOR 123 $24

11 RGYRO= 111

19 RGYRO, 111, SYNC, 10, RPM, 0., 2500.

27 28 GRID, 101, , 0., 0., 0.29 GRID, 102, , 1., 0., 0., , 1430 GRID, 103, , 2., 0., 0.31 GRID, 104, , 0., 0., 0.32 GRID, 105, , 2., 0., 0.33 34 RBE2, 1001, 102, 123456, 101, 10335 RBE2, 1002, 101, 123456, 10436 RBE2, 1003, 103, 123456, 10537 38 CONM2, 1004, 102, , 50.,39 , 5.0, , 15.0, , , 15.040 41 CELAS1, 1005, 1000, 104, 242 CELAS1, 1006, 1000, 104, 343 CELAS1, 1007, 1000, 105, 244 CELAS1, 1008, 1000, 105, 345 PELAS, 1000, 1.0E+5, 0.046 47 ENDDATA

25 ROTORG 10 101 THRU 10326 RSPINR, 10, 101, 102, , RPM, 9999.

Single Spool RotorCampbell Diagram and Critical Speeds

Mode 1,2

Mode 3

Mode 4

1/rev2/rev

First Critical

Second Critical

Third Critical

Dual Spool Rotor Asynchronous Vibration

1 $2 $ ROTOR DYNAMICS SAMPLE PROBLEM3 $ Dual Spool Rotor, Asynchronous Vibration4 $5 6 ID SAMPLE ROTOR7 SOL 1078 DIAG 5, 8, 56 9 CEND

10

12 DISP = ALL13 CMETHOD = 10014 15 BEGIN BULK16

18 19 EIGC,100,CLAN,20 , 0., 0., , , , , 1421 22 $23 $ ROTOR 124 $25

29 ...52 $53 $ ROTOR 254 $55

59 ...81 ENDDATA

11 RGYRO = 300

17 RGYRO, 300, ASYNC, 20, FREQ, 0., 100. , 40.

26 ROTORG 10 101 THRU 10427 RSPINR, 10, 101, 102, , FREQ, 20., 25., 35.,28 , 50.

56 ROTORG 20 201 THRU 20357 RSPINR, 20, 201, 202, , FREQ, 10., 20., 30.,58 , 40.

Dual Spool RotorRelative Rotor Speeds

Dual Spool RotorCampbell Diagram and Critical Speeds

Mode 1,2

Mode 3,4

Mode 5

1/rev

1st & 2nd Critical

3rd & 4th Critical

5th Critical

Mode 6

6th Critical

Dual Spool Rotor Transient Response

Squeeze Film Damper

MSC.Nastran RotordynamicsSummary

• Unified front and team effort enabled rotordynamics to be implemented into MSC.Nastran

• Rotordynamics primer is available for distribution

• MSC.Software did an outstanding job of satisfying customer’s needs