GT Power at GM Powertrain
Gerry Clark
Two Process Areas:
Isopower relationships for powertrain to vehicle integration.
An easily generated resource for estimating engine output based on
induction and exhaust restriction.
Exhaust manifold boundary condition generation.
Non-coupled GT-Power simulation used to quickly generate CFD
boundary conditions for use in thermal-structural simulations.
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 1
Bio:
Gerry Clark
GM Powertrain
Synthesis & Analysis Department
Valvetrain & Engine Performance Group
• Engine Simulation
• Valvetrain/Camshaft Design
Focus: ‘Small Block’ Family of OHV 90 degree V
gasoline car and truck engines.
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 2
5.7L, LS1 V-8 350HP
LS6 405 HP
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 3
6.0 L V-8: LQ9 345 BHP 380 lbf-ft
LQ4 HD 300 BHP 360 lbf-ft
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 4
5.3L V-8: LM7 285 BHP 325 lbf-ft
4.8L V-8: LR4 275 BHP 290 lbf-ft
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 5
Isopower
Problem:
Requests for power and torque of existing
engine platforms at different inlet and exhaust
restriction levels take resources and time to
answer.
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 6
Isopower
Solution
Develop and ‘release’ a chart/look up table for
distribution to engine customers which relates
rated engine power to exhaust and intake
restriction.
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 7
Isopower
Process
Use GT Power steady flow induction system models to define 3 to 5
levels of induction system flow specifications.
•Use peak power mass air flow +.
• ‘220 g/s at -3 kPa, -4kPa, -5kPa, -6kPa.’
•Vary pipe size, MAF restriction, filter restriction to
achieve target flow levels on steady flow model.
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 8
Isopower
Process
Use GT Power steady flow induction system models to define 3 to 5
levels of induction system flow specifications.
•Use peak power mass air flow +.
• ‘220 g/s at -3 kPa, -4kPa, -5kPa, -6kPa.’
•Vary pipe size, MAF restriction, filter restriction to
achieve target flow levels on steady flow model.
Use correlated GTPower full engine simulation with each induction
model to determine restriction at specific power levels.
•Install first induction system on engine model.
•Run model at peak power RPM
•Use optimizer to vary exhaust restriction until target
power levels are obtained.
•Repeat for all induction systems.
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 9
TRUCK ENGINE
GT Power Rated Power Estimation
vs Induction Restriction and Back Pressure
Induction Restriction kPa @ 220 g/s
Isopower
7
6
260 BHP
275 BHP
290 BHP
DYNO 285 HP
5
4
3
2
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2
2.1
Back Pressure (Bar Abs.)
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 10
Isopower
Summary:
Isopower exhaust and intake restriction relationships for
existing engine to vehicle integration:
A resource for estimating engine output based on vehicle restriction
conditions.
A resource for developing vehicle restriction specifications based on
engine output requirements.
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 11
Isopower
Questions?
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 12
Exhaust Manifold Boundary Conditions
Using 1-D Simulation.
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 13
Exhaust Manifold Thermal Structural
Process:
• Engine simulation provides exhaust manifold
boundary conditions (Temperature, Pressure,
Density and Mass Flow).
• 3-D CFD simulation with above boundary
conditions develops cycle average map of internal
exhaust manifold surface gas temperatures and
heat transfer coefficients.
• Finite element model uses cycle average thermal
boundary condition map as input to thermal
structural simulation.
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 14
Exhaust Manifold Boundary Conditions
Issue:
1-D 3-D Coupled models provide insight to 3-D flow in
complex geometries, and allow interactive tuning effects
to show. (Example: intake manifold plenum)
When 1-D models provide appropriately tuned flows for
the situation under study, does coupling provide
benefits?
Probably not when looking at exhaust manifold thermal
boundary conditions.
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 15
Exhaust Manifold Boundary Conditions
Process:
1-D engine simulation inputs:
•Correlated model
•Target RPM
•Air-fuel ratio
•Spark/combustion timing.
•CFD interface locations
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 16
Exhaust Manifold Boundary Conditions
Process:
1-D engine simulation inputs:
•Correlated model
•Target RPM
•Air-fuel ratio
•Spark/combustion timing.
•CFD interface locations
1-D engine simulation outputs at interface locations
(tabular data vs. crank angle):
•Temperature
•Pressure
•Density
•Mass Flow
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 17
CFD Boundary Condition Map
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 18
Exhaust Manifold Boundary Conditions for
Thermal - Structural Simulation
Summary:
Non-coupled GT-Power simulation used to quickly
generate CFD boundary conditions for use in
thermal-structural simulations.
Avoided complex analysis procedure, saving
resources for projects with more interactive
simulation requirements.
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 19
Acknowledgements:
Isopower:
– Rick Hart
– Sameer Ogale
– Dan Whitney
Boundary Conditions:
– Wen-Tsung Chuang
– Mark Loehr
– Gary Mandrusiak
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 20
Exhaust Manifold Boundary Conditions for
Thermal - Structural Simulation
Questions?
Gerry Clark
Valvetrain and Engine Performance
POWERTRAIN
Slide 21