Presentation on Automotive Application Field

케이씨엘이

김연수 대표

kysoo9311@gmail.com

• External Aerodynamics

• UTM – Heat damage

• Engine Cooling

• Aero-acoustics

– Side mirror, Sun roof, Wiper, Fan

• HVAC – Ventilation synthesis with various modes

– Ratio on Volume rate of Ventilation duct

– Defog / Defrost

– Cowl plenum device

– Thermal comfort

• IC Engine & Peripheral devices

– In cylinder

– Intake & Exhaust ducts

– Pumps

• Others

– Lamp, Brake, Soiling Contamination, Fuel Tank

. . . . . .

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Simulation Items in Automotive field

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External Simulations

Aerodynamics

• Challenges– Resolve pressure distribution around the

vehicle– Minimize vehicle drag

(to improve fuel economy)– Assess vehicle handling and stability

(side forces, lift)

• Advantages of ANSYS– High-end turbulence models

– Sophisticated and accurate numeric

– Highly efficient transient solvers

– Mesh-adapt-on-the-fly ability

– Industry-leading parallel scalability

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Aerodynamics

Aerodynamic Forces

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Rear Wake

Underbody fairingEngine room

Aerodynamics

Evolution of CdA

GMK Spark

GM Volt

BENZE BMW

GM K AVEO

Rear spoilerRear lamp, bumper radius

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Engine Cooling

• Objective– Flow rate through cooling package under

Idle condition and Max. vehicle speed– Coolant inlet and outlet temperatures

• Justifications for using CFD for the Engine cooling applications– Decide Opining area satisfying Engine

cooling although reducing CdA– Select an adequate Radiator and Fan – Decide whether of not installing sealing

and fairing in front of Radiator and under Engine

– Reduce cost (eliminate or reduce prototype testing)

• Given conditions:– Vehicle and fan speeds– Heat exchanger performance data

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Aero – acoustics: Sunroof buffeting

[Pa]

*

*

Simulation, [50 km/h]

Measurement

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Aero – acoustics: Side Window Buffeting

D. Hendriana, S. Sovani, and M. Schiemann, “On Simulating Passenger Car Side Window Buffeting,” SAE 2003-01-1316, 2003.

• Compressible flow (ideal gas) with CAA– RNG/LES Turbulent model – Second order for time discretization– Second order for space discretization– PISO for pressure-velocity coupling

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Aero – acoustics: Side Mirror

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Point 101

Iso-contour of instantaneous vorticity magnitude (LES)

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Aero – acoustics: Ventilation Fan

j

R = 1 m

Acoustic Pressure Variation (Pa)

Power Spectral Density (W/m2)

1 BPF

2 BPF

j = 45

j = 60

j = 75

Receiver’s Position

Static Pressure (Pa)

2000 RPM, BPF = 133.3 Hz11

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Internal Simulations

Ratio on Volume rate of Ventilation duct

• Air from the center inlets passes straight to the outlet

• Air from the side vents undergoes more circulation before exiting

• Temp. contours show the thermal distribution felt by the passengers

• Analyses of this type help engineers design ventilation systems that produce thermal comfort for all the passengers under a variety of conditions

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Defog / Defrost

• Procedure on Defrost simulation– Ice initially covers the windshield, warm

air from the defroster melts the ice– Uses a phase change model to track the

melting– CFD results predict thinning ice as well as

melted region

• Why is CFD important for Defrost performance???– Defrost performance in a new vehicle

development must satisfy the standard of government regulations Uses a phase change model to track the melting

– CFD Simulation can provide many countermeasures for defrost improvement

– CFD could reduce the budget and duration spent for performance improvement

0.00

5.00

10.00

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25.00

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35.00

0 - 1 1 - 2 2 - 3 3 - 4 4 - 5 5 - 6 6 - 7 7-8

Pe

rce

nta

ge

(%

)

Velocity (m/sec)

Distribution of speed on windshield A and A' zone

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Cowl Plenum Device

• Objective– Evaluate duct performance in terms of

airflow efficiency– Predict precisely the behavior of water in

Cowl Plenum room, and evaluate if there is the ingress of water to HVAC or not

• Main parts– Grills, Deflector, Scoop plate, Entry area

of HVAC ,Cross area of Cowl Plenum room

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Thermal Comfort

• Thermal comfort is largely a state of mind, separate from equations for heat and mass transfer and energy balances

• The most common approach to characterize thermal comfort has been to correlate the results of psychological experiments to thermal analysis variables

• The level of comfort is often characterized using the ASHRAE thermal sensation scale, one International standard

• Main Parameters– Humidity, Radiation temperature,

clothing status, average surface temperature, averaging velocity

– PMV, PPD, ET

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ICE Simulation

In Cylinder

• Scope of WB-ICE Tool– Automated mesh generation

for all 4 stroke engines– Automated case setup for “cold-flow”

and “Combustion” type simulations– User hooks to setup case for

combustion simulation

WB-ICE DesignModeler

ANSYS Meshing

FLUENT Solver

CFD Post

Workbench IC Engine Workflow

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In Cylinder: Report

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Intake / Exhaust manifold

• Perform flow, thermal, species tracking (EGR) and/or combustion

• Conjugate heat transfer analysis including solid

• Steady-state flow bench analysis

• Transient– BC specified via tabular data– User-Defined-Function– Fully coupled to 1d engine simulation

codes

• Detailed model including– plenum and runners– throttle body and plate– exhaust gas re-circulation (EGR)

passage– positive crankcase ventilation (PCV)

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• Numerous pump classifications, based on displacement, design

• Pump classification based on displacement (amount of fluid delivered per cycle):– Non-positive displacement pumps:

discharge flow continuously– Positive displacement pumps: discharge

intermittently

• Rotary– Gerotor Pumps– Gear pumps– Lobe pumps– Screw pumps

• Reciprocating– Vane pumps– Piston pumps

Pump

Total head reduction due to Cavitations

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Various main parts

• Objective– Predict the precise thermal load at

main parts like REFLECTOR, LENS, HOUSING and BEZEL, which is related to thermal deformation.

– Understand the mechanism of generation and decay of Condensation on Lens

• Reason of Condensation in Lamp– Poor ventilation in Lamp– Unsuitable location of holes– Improper deployment of interior parts

• Boundary conditions are:– Radiation (DOM)– Conduction & Convection– EWFM for Condensation simulation

Lamp

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• Challenges– Design brakes and wheels that are

durable and can sustain variable loads– Predict stress and fatigue – Predict local temperature distributions

and thermal loads– Optimize brake venting

• Advantages of ANSYS– Flow and structural solution from the

same CAE vendor– Easy and seamless transfer of CFD and

FEA data between applications

Brake System

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• Vehicle driving through shallow water basin

• Identify the correlation between mass fraction and accumulation with photo of contamination

• CFD analysis: flow field, mass transfer and diffusion

• Evaluation: mass fraction next to the body surface regarded as indicator for accumulation of dirt

Contamination

Limitation Experiment

CFD

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Tank Sloshing

• Traditional approach for a simulation– Body force is needed because the

reference frame is not an inertial frame– Body force is modeled by changing

gravitational force through a scheme file

• Dynamic Mesh (DM) – The tank is moving in an absolute frame.

The tank velocity, as opposed to the acceleration, is specified using a UDF.

– Solid body motion is assigned to all cells and boundary faces. So, there is no special requirement on mesh element type. The same mesh from the traditional method can be used

– Since an absolute frame is used, no body force is needed

• Clocking & Sloshing Noises in a tank

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