Title: REDESIGN OF AN AIRCRAFT ENGINE EQUIPMENT USING 3D DYNAMIC WHOLE ENGINE MODEL
1REDESIGN OF AN AIRCRAFT ENGINE EQUIPMENT USING 3D
DYNAMIC WHOLE ENGINE MODEL
- Company SNECMA MOTEUR
- Engineering System Integration Division
- Author Alain Mazelet
2Background of the study
- Baseline engine in service
- New application implies modification of one or
more equipments - Impact of these modifications on engine carcass
integrity is not a concern - Main concern is local impact around equipment
- Need to assess if local redesign is required to
comply with blade out regulation - WEM model is used to redesign equipment without
blade out test
3Calculation process for the base line equipment
SNECMA Test division
Forced response test data
Correlation
Bladeout test data
Correlation
Correlation
Forced response calculation
Bladeout calculation
Interface acceleration
SNECMA Integration division
WEM
Simplified equipment model
Detailed equipment model
Stress analysis
Equipment designer
4Calculation process for the modified equipment
SNECMA Test division
Vib. survey test data
Correlation
SNECMA Integration division
Vib. survey calculation
WEM
Simplified equipment model
Equipment designer
5Equipment models
- Simplified model enables general loads and
displacement calculation beam / shell / masses /
springs / rigid bodies
- Detailed model enables stress analysis volume
elements model
6Forced response test
- Equipment is mounted on fan frame and fan case to
get adequate boundary conditions - White noise excitation is produced with a dash
pot (0-300 Hz) - 83 dofs are measured on the structure with
accelerometers - 57 modes are detected, we focus on 17 which were
more representative of equipment displacement
F
7Forced response test / model correlation
- Correlation parameters mount stiffness , flange
stiffness, masses and inertia - Correlation method MAC / FDAC for deform shape
correlation, FRF comparison for each
accelerometer. - Good correlation was achieved between 30 and 150
Hz
8Whole engine blade out model
- Whole engine and test rig model (shell, beam,
masses, rigid bodies ) - NASTRAN V69.1 (SOL109) DMAP alter for
gyroscopic effect - Non linear element between fan and fan case
- 330 000 dofs (11000 after condensation)
- Loads unbalance load (one blade), impact of the
blade on the fan case, decrease of thrust load,
and deceleration moment.
9Blade out test / model correlation
bearing load
Equipment link load
calculation test
Equipment acceleration
10Equipment design
- PROCESS
- Run blade out transient calculation
- Extract engine / equipment interface acceleration
- Run detailed equipment transient response under
enforced interface motion (Lagrange multiplier
method or big mass method) - Conduct stress analysis
Interface acceleration
Bladeout calculation with simplified equipment
model
Detailed equipment model
Stress analysis
- SNECMA Moteur does not need to export WEM, DMAP
etc - Equipment designer does not need to export
detailed model - SNECMA and equipment designer do not need to have
the same FEM code, no translation is needed
11CONCLUSION
- WEM gives a satisfactory representation of the
engine behaviour - Engine equipment design can be achieved with
dynamic transient criteria, static equivalent
criteria are not used anymore. - Data exchanges between SNECMA and equipment
designers are limited to interface acceleration - MSC/NASTRAN DMAP solutions give us the capacity
to run the whole process including condensation,
non linear elements, stress analysis ...