MSC.Nastran Rotordynamics. Types of Analyses. Engine performance. • critical
speeds. • whirl. • forced response (unbalance, cabin noise). • damping.
An MSC.Nastran Primer for Rotordynamics Chuck Lawrence NASA 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 Model Engine Static Structure
MSC.Nastran Rotordynamics Background • 1998 Meeting with engine and airframe manufacturers and MSC.Software • All manufacturers performing similar types of 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
MSC.Nastran Rotordynamics Process • 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 Unique Features • General Finite Element Capabilities • 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 Contents I. Single Spool Rotor 1. Geometry 2. Gravity Loads 3. Maneuver Loads 4. Transient Unbalance Response 5. Synchronous Vibration (Critical Speeds) 6. Asynchronous Vibration (Whirl Analysis) 7. Comparison of Damping Models II. Dual Spool Rotor 1. Geometry 2. Synchronous Vibration (Critical Speeds) 3. Asynchronous Vibration (Whirl Analysis) 4. Transient Unbalance Response III. Squeeze Film Damper IV. Three Dimensional Model Reduction
Single Spool Rotor With Rotor and Support Damping Unbalance Load Disk 101
Rigid Shaft 102
103 (105)
(104)
Support Support Damper Springs
Rotation Vector
Rotor Damper
Y
X Z
Single Spool Rotor Transient Analysis 1 2 3 4 5 6 7 8 9 10 11
$ $ ROTOR DYNAMICS SAMPLE PROBLEM $ SINGLE ROTOR, UNBALANCE LOAD $ ID SAMPLE ROTOR SOL 129 DIAG 5, 8, 56 CEND RGYRO= 111
12 13 14 15 16 17 18 19
TSTEP= 100 SET 500 = 102 DISPLACEMENT(PUNCH) = 500
20 21 22 23 24
TSTEPNL, 100, 40000, 1.E-3, 20
BEGIN BULK UNBALNC, 111, 100.0, 102, 0., 1., 0., , 1.0, 0.0, 0.0, 0.0, , NONE
$ $ ROTOR 1 $
26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
ROTORG 10 101 THRU 103 RSPINT, 10, 101, 102, , RPM, 100 TABLED1, 100 , 0.0, 800., 100.0, 800., ENDT GRID, 101, , 0., 0., 0. GRID, 102, , 1., 0., 0., , 14 GRID, 103, , 2., 0., 0. GRID, 104, , 0., 0., 0. GRID, 105, , 2., 0., 0. RBE2, 1001, 102, 123456, 101, 103 RBE2, 1002, 101, 123456, 104 RBE2, 1003, 103, 123456, 105 CONM2, 1004, 102, , 50., , 5.0, , 15.0, , , 15.0 CELAS1, 1005, 1000, 104, 2 CELAS1, 1006, 1000, 104, 3 CELAS1, 1007, 1000, 105, 2 CELAS1, 1008, 1000, 105, 3 PELAS, 1000, 1.0E+5, 0.0 ENDDATA
Single Spool Rotor Transient Response
Single Spool Rotor - Critical Speeds 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
$ $ ROTOR DYNAMICS SAMPLE PROBLEM $ SINGLE ROTOR, CRITICAL SPEEDS $ ID SAMPLE ROTOR SOL 107 DIAG 5, 8, 56 CEND RGYRO= 111 DISP = ALL CMETHOD = 100 BEGIN BULK EIGC, 100, CLAN, , 0., 0., , , , , 10 RGYRO, 111, SYNC, 10, RPM, 0., 2500. $ $ ROTOR 1 $
25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
ROTORG 10 101 THRU 103 RSPINR, 10, 101, 102, , RPM, 9999. GRID, 101, , 0., 0., 0. GRID, 102, , 1., 0., 0., , 14 GRID, 103, , 2., 0., 0. GRID, 104, , 0., 0., 0. GRID, 105, , 2., 0., 0. RBE2, 1001, 102, 123456, 101, 103 RBE2, 1002, 101, 123456, 104 RBE2, 1003, 103, 123456, 105 CONM2, 1004, 102, , 50., , 5.0, , 15.0, , , 15.0 CELAS1, 1005, 1000, 104, 2 CELAS1, 1006, 1000, 104, 3 CELAS1, 1007, 1000, 105, 2 CELAS1, 1008, 1000, 105, 3 PELAS, 1000, 1.0E+5, 0.0 ENDDATA
Single Spool Rotor Campbell Diagram and Critical Speeds 2/rev
1/rev Mode 4 Third Critical
Second Critical
Mode 3 Mode 1,2
First Critical
Dual Spool Rotor Asynchronous Vibration 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
$ $ ROTOR DYNAMICS SAMPLE PROBLEM $ Dual Spool Rotor, Asynchronous Vibration $ ID SAMPLE ROTOR SOL 107 DIAG 5, 8, 56 CEND RGYRO = 300 DISP = ALL CMETHOD = 100 BEGIN BULK RGYRO, 300, ASYNC, 20, FREQ, 0., 100. , 40. EIGC,100,CLAN, , 0., 0., , , , , 14 $ $ ROTOR 1 $
26 27 28 29 . . . 52 53 54 55 56 57 58 59 . . . 81
ROTORG 10 101 THRU 104 RSPINR, 10, 101, 102, , FREQ, 20., 25., 35., , 50.
$ $ ROTOR 2 $ ROTORG 20 201 THRU 203 RSPINR, 20, 201, 202, , FREQ, 10., 20., 30., , 40.
ENDDATA
Dual Spool Rotor Relative Rotor Speeds
Dual Spool Rotor Campbell Diagram and Critical Speeds 1/rev Mode 6 6th Critical
5th Critical
Mode 5
Mode 3,4 3rd
&
4th
Critical Mode 1,2
1st
& 2nd Critical
Dual Spool Rotor Transient Response
Squeeze Film Damper
MSC.Nastran Rotordynamics Summary •
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
