Turbocharger nonlinear
rotordynamics
MAJOR APPLICATION: Passenger vehicle and commercial vehicle turbochargers,
micro-turbomachinery
Sponsor: Honeywell Turbo Technologies (Torrance, CA,
Thaon-les-Vosges, France)
TC
supported on (left) SFRB (right) FRBs provided by Honeywell Turbo Technologies
Objective: To advance (experimentally validated)
computational tools for prediction of the dynamic forced response of
turbocharger rotors supported on FRBs
Status:
Honeywell Turbo Technologies continuously support this project since
2000. The turbocharger (TC) test rig was dismantled after testing three TC
units. DAQ system and instrumentation developed to record shaft motions to 200
krpm, including floating ring speed. A Virtual Laboratory for prediction of TC
response is currently in place. The work aims to correlate nonlinear model
predictions with test data available from the sponsor Hot Gas Test Stands in LA
and France. The computational tool allows for fast product development with
substantial savings to the sponsor.
Current
Work proprietary
VIRTUAL LABORATORY
Numerical
predictions based on XLTRC2 and bearing nonlinear models (XLBRG) show excellent correlation with test data
for a TC supported on fully-floating ring bearings as well as for a unit
supported on semi-floating ring bearings. The side load due to the feed
pressure must be accounted in the analysis to predict reliable results
comparable to the test data.
The latest version
of XLBRG features seven different heat convection
models. In addition, based on bearing geometry, XLBRG features three types of bearing models:
a)
Bearing
with inlet feed pressure at ONE END
b)
Bearing
with inlet feed pressure at MIDPLANE
c)
Bearing
with UNEQUAL LENGTHS (LEFT & RIGHT) inlet feed pressure at center between
lands
Some of the major
advances in analytical study conducted at Turbo Lab include but are not limited
to:
a)
Predictions
of linear and nonlinear responses of various Turbochargers (TC) with constant
shaft speed
b)
Effect
of compressor cross coupled stiffness and thrust bearing moment coefficients on
TC dynamic response
c)
Effect
of increasing inner film clearance on TC shaft motions
d)
Predictions
of TC transient speed response with various acceleration and deceleration rates
e)
Predictions
of TC nonlinear response with engine housing base excitations
f)
Modifications
of the XLTRC2 Excel GUI to be compatible with new bearing features
in XLBRG
Please note that in most cases predictions
are validated against test data. Rotor models developed in XLTRC2
are validated by measuring the free-free mode natural frequencies.
TEST RIG FACILITY
Example of a TC rotor model supported on FRBs in XLTRC2
Predicted and measured TC dynamic response – shaft speed 29
to 243 krpm
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