GT-SUITE and TAITherm Coupling Methodology for Transient ... · 3D CFD GT-Suite 1. Validation of...

07-OCT-2019 - page 1 European GT-SUITE Conference 2019TOYOTA MOTOR EUROPE (TME)

GT-SUITE and TAITherm Coupling Methodology for

Transient Cabin Simulation Using 3D CFD Data

European GT-SUITE Conference 2019

TME Nick Buyens, Jeroen De Smet

AKKA Gauthier Carteni (on-site consultant)

Powertrain 1 – Model Based Design


Contents

1. Project background

2. Methodology

3. Initial model results

4. Future development


Project Background

Reference: Stevens, M. 2015, ‘FleetCarma Goes Deep Into The Data’,

CHARGED EV MAGAZINE, Issue 17, Jan-Feb, p.56-61

Winter Ideal Summer

Cabin heating Cabin cooling

Cabin heating has a significant energy consumption impact for electrified vehicles

Electrified vehicles don’t have access to sufficient

heat from traditional “free” waste heat sources

(i.e. combustion engine) in winter

(HEV / PHEV) – turn on the engine to provide

additional heat at cost of fuel consumption

(PHEV / BEV) – use additional heating devices

at cost of electricity consumption


Project BackgroundA full vehicle model is required to virtually optimise cabin comfort and energy consumption

Development in wind tunnel requires

Prototype vehicle preparation

Extensive testing process

(0.5h test + 4h soak)

40+ sensors for comfort assessment

Resource inefficient

Objective

System Level

PT HVAC Cabin

+ +

Thermal Management Development

PT + HVAC + Cabin

Full Vehicle

Virtual vehicle model

Powertrain

model

Powertrain

ECU

HVAC

model

HVAC

ECU

Cabin

model


Project Background

3D accuracy

highlow

Complexity

Calculation time

low

high

A

B

CDetailed 3D approach

10M cells

400xRT

B

Mapped 3D approach

200K cells

1-2xRT

C

Cabin modelling methods

GT-SUITE methodology for 3D cabin heating with fast simulation time was evaluated

Cabin model image

Cabin

model

Flowrate and

temperature at

the HVAC outlets

Air temperature at

any point in the cabin

Solid temperature at

any point in the cabin

Cabin outputsCabin inputs

Model targets1. Simulate transient 3D cabin heat-up

2. Fast calculation time < 2xRT

‘Simple’ 0D approach

1 cell

0.1xRT

A


Methodology – Principle A standard GT-Suite & TAITherm co-simulation process using 3D CFD data was developed

Material

data

Air temperatures

Solid temperatures

Co-simulation

CAD

Provide geometryCFD Mesh

Simplified

Mesh

CFD maps

CFD run for each

cabin condition

CFDCFD


Methodology – CFD steady stateThermal 3D CFD simulations are used to accurately capture cabin flow and heat flux

Low High

CFD

inlet

CFD interfaces

GT openings

CFD inlet &

ducts

Cabin outlets

Cabin walls

Constant high temperature

Imposed volume flow rate

Constant low temperature

Recirculation & ventilation

Interfaces used as inlet in GT


Methodology – Principle Co-simulation methodology developed with GT-Suite & TAITherm

Material

data

Air temperatures

Solid temperatures

Co-simulation

CAD


Simplified

Mesh

CFD maps

Calculated once for

each case

CFD


Methodology – CFD maps

3D CFD maps contains 7 result files per case:

Extensive 3D CFD data are mapped on the coarsely discretised GT cabin

Absolute Pressure Field

Boundary Heat Flux

Inflow & Outflow Rate

Air & Solid temperaturesTurbulent Viscosity Field

Velocity Field

CFD

CFD maps

① ② ③

④ ⑤ ⑥⑦


Methodology – Principle

Material

data

Air temperatures

Solid temperatures

Co-simulation

CAD


Simplified

Mesh

CFD maps

Calculated once for

each case

CFD


Methodology – GT model discretisationGT v2019 process is time-consuming New process flow under development for GT v2020

Closed Surface

3. Vents shape

4. Vents location

5. Sensors position

1 hour

7 hours1. Ducts removed

2. Vents closed

CAD

V

2

0

1

9

Export Mesh

10 minutes

30 minutes

1. Sensors position

Final GT model

Discretized6 days

Total7 days

Discretized15 minutes

Total1 hour

V

2

0

2

0 CFD


￭ 61 CFD maps

(steady)

GT look-up

Switch

Interpolate

Transient cabin flow is only

dependent on 4 HVAC parameters:1. Inlet mode

2. Outlet mode

3. Air mix

4. Blower level

Methodology – GT flow processingGT interpolates between mapped steady CFD points at every simulation time step

HVAC mode

Flow rate level

Time [s]

Velo

city [

km

/h]

HV

AC

mode [-]

Flo

w r

ate

level [-

]



Material

data

Air temperatures

Solid temperatures

Co-simulation

CAD


Simplified

Mesh

CFD maps

Calculated once for

each case

CFD


CFD

Methodology – TAITherm model set-upTAITherm model is set up following standard procedures

1. Ducts removed

2. Vent openings kept

Simplified Mesh

1. Initial temperature

2. External temperature

and velocity (transient)

Material properties



Material

data

Air temperatures

Solid temperatures

Co-simulation

CAD

Provide geometry

Co-simulation

CFD Mesh

Simplified

Mesh

CFD maps

Calculated once for

each case

CFD


Methodology – Transient runFinal co-simulation can simulate cabin model on a transient cycle below 2x real time

InterfaceMesh

TAir & HTC

TSolidLow High

Temperature

Low High

Temperature

Velo

city [

km

/h]

Time [s]


Initial results – Air temperatureModel shows good prediction, but accuracy near cabin flow inlets to be improved

Time [s]

Te

mp

era

ture

[ºC

]Te

mp

era

ture

[ºC

]

10ºC

10ºC1

2

1

2

Simulation conditions

Ambient: Winter

HVAC setting: Cabin heating

Driving cycle: WLTC

Model inputs: CWT test data

※ CWT = Climatic Wind Tunnel


Initial results – Air temperatureModel shows good prediction, but absolute accuracy at end of cycle to be improved

10ºC

High speed area

to be investigated

Te

mp

era

ture

[ºC

]V

elo

city [km

/h]

Time [s]


Future development – next steps Potential model improvement steps were identified and will be performed

3D CFD

GT-Suite

1. Validation of GT-Suite mapped flow1. Set up transient CFD

2. Set up co-simulation CFD-TAITherm

3. Check accuracy of GT vs. CFD

(airflow & temperature)

2. Investigate further model improvements e.g.1. Effect of external airflow

(realistic aerodynamics)

2. Further TAITherm model improvements

(material properties, air gaps etc.)


Future development – next applicationApplication of the methodology to other mobility solutions requires additional development

Future Mobility as a Service (MaaS)

1. Fully electrified

2. Large interior volumes + window area

Development of transient door

opening prediction is needed

Commercial vs. private

initial heat-up has low priority

Ride sharing application

transient door opening


Thank you

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