Model-based Calibration using Coupled Hydraulic and ... · Combustion Injection and mixture...

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Model-based Calibration using Coupled Hydraulic and Combustion Simulation

2016 North American GT Conference 2016

Monday, November 14th 2016, Plymouth, Michigan

Dennis Backofen, Laura Wöhlert, Dr.-Ing. Reza Rezaei, Benjamin Tilch

Agenda

• Reverse engineering for hydraulic simulation

• 1D injector model

• Physical combustion model

• Methodical approach

• Results

• Control chamber geometry

• Nozzle discharge coefficient

• Conclusion

Directly from the tier 1

Reverse Engineering

How to get a 1D-simulation model

Black Box

+ immediate start-up

- Black-box model

- No ability to change

the model parameters

- No model for

predictive work

Reverse engineering+ Fully configurable 1D

+ Model usable for

predictive work

+ Understanding of the

functionality

- Effort to determine the

important geometrical

values

Distructive dismounting

Non-distructive dismounting

CT-Analysis

1D Simulation – Reverse Engineering

Data collection

Destructive dismounting of the

component

Non-destructive dismounting of the component

Use of technical drawings e.g. CAD data

(ProE, Catia, Solid Edge, etc.)

Use of analog/digital measuring technologies

Optical analysis (microscope,

computer tomography)

Determination of characterstic numbers (e.g. spring

characteristic)

Nozzle flow, injection

rate and amount

Nozzle jet force

penetration, spray angle,

spray surface,

droplet size, droplet

distribution, droplet velocity

vaporization rate

Needle lift

Line pressure

Leakage

Rail pressure

Pump torque

Pressure at the

pump outlet

Pump flow

1D Simulation – Reverse Engineering

Validation with measured data

Depending on rail pressure, counter-pressure, control duration, fuel (gasoline, diesel,

alt. fuels, gas, bad fuels), control strategy (single/multi-injection, etc.)

Valve lift

Leakage

Current and voltage to

control the injector

1D Injector Model

Injector Model Specifications

Application area Commercial vehicle

Number of nozzle holes 8

QStat 2460 cm³/60s @100

actuation duration

Gaincurves at constant rail pressure

x = Simulation

= 100 MPa (measurement)

= 150 MPa (measurement)

Good correlation between simulation and measurement results

Simulation of the Solenoid Actuation

Time [ms]

jectio

Measurement

Simple solenoid model

New solenoid model

• Simple solenoid model doesn‘t show the same time behaviour like the real injector

• Time delays in the opening and closing phase because of losses (e.g. eddy

current) can‘t be modeled

• Exact modelling of time delays are important e.g. for the combustion simulation

• Influence of the solenoid actuation is more intensive with GDI injectors

New solenoid model considers the time

delays during the opening and closing

phase of the injector.

Modeling Approaches of the Combustion ModelModel Structure

Gas Exchange

Simulation

(GT Power)

• The developed phenomenological combustion model is used for engine process

simulation and coupled with a GT POWER gas exchange model for intake flow

simulation.

IAV Combustion Model

Injection Rate Module

Mixture Preparation Module

Turbulent Kinetic Energy Module

Ignition Module

Combustion Module

Application ExamplesIAV Combustion Model

IAV uses its own combustion model for 1D engine simulation or for the

physically-based development or calibration of engine control strategies.

MotivationApplications of the physical combustion model

Ignition and combustion

modeling

Engine Process

Simulation (1D)

Emission

Calculation (NOx)

Model-Based

Calibration

Basis for Dual-Fuel

Combustion

Injection and mixture

formation modeling

• The phenomenological combustion model was

developed at IAV (see SAE 2012-01-1065) and is

based on physical modeling of in-cylinder processes

such as Injection, ignition, and premixed and diffusive

combustion.

• Further development of the combustion model and a

novel NOx reaction kinetics are published in.

Phenomenological modeling of combustion and NOx

emissions using detailed tabulated chemistry methods in

diesel engines. International Journal of Engine Research

Physically-Based

Engine Control

Methodical Approach

Analysis of the change of design parameters during lifetime of a diesel injector

Smaller outlet diameter of the control chamber

Smaller inlet diameter of the control chamber

Smaller discharge coefficient

of the nozzle holes

Deposits

at the

throttles

Coking nozzle holes

Multiple Injection, without

tracking of the fuel amount/

Multiple/single injection,

with & without tracking of

the fuel amount/BR50%

Variation of Control Chamber Geometry

Smaller inlet diameter → early opening of the

nozzle holes and a higher injection rate especially in the pre-injection

Later closing of the nozzles holes → more intensive premixed combustion and slightly

higher and longer diffusion combustion

Smaller outlet diameter→ delay of the nozzle opening and earlier closing of the nozzles

holes → less premixed combustion and decrease of the diffusion combustion

ction R

Crank Angle [deg]

-10 0 10 20 30

Smaller inlet diameter contol chamber Smaller outlet diameter control chamber Standard

Crank Angle [deg]

-10 0 10 20 30 40 50 60 70 80 90 100

Smaller inlet diameter contol chamber Smaller outlet diameter control chamber Standard

More intense influence of the outlet diameter on the injection rate and combustion

process

NOxOutput

ppm kW

Standard 1102 55.06

Smaller diameter inlet control chamber 1322 58.46

Smaller diameter outlet control chamber 664 47.63

Def. Operation point

Variation of Nozzle Discharge Coefficient

ction R

Crank Angle [deg]

-10 0 10 20 30

Standard Smaller nozzle-cd-value

Crank Angle [deg]

-10 0 10 20 30 40 50 60 70 80 90 100

Standard Smaller nozzle-cd-value

No influence on the the pre-injection and premixed combustion by decreasing the

nozzle discharge coefficient

Significant influence on the maximum injection rate and burning duration by decreasing

the nozzle discharge coefficient

NOxOutput

ppm kW

Standard 1102 55.06

Lower cd-value nozzle holes 607 46.25

Def. Operation point

Variation of Nozzle Discharge Coefficient and Control of the Injected Mass/BR50%

Crank Angle [°CA ATDC]

-10 0 10 20 30

Pi = 44.0 kW

-10 0 10 20 30

11.1 °CA ATDC

cd = 0.88 (216 mg)

Reduction of the nozzle discharge coefficient leads to a decreasing of the

maximum injection rate and reduction of the maximum cylinder pressure or

the burning rate and power respectively (12 %)

-10 0 10 20 30

Pi = 44.0 kW

Pi = 38.9 kW (D 11,8%)

-10 0 10 20 30

11.1 °CA ATDC 11.0 °CA ATDC

cd = 0.88 (216 mg)

cd = 0.70 (192 mg)

Tracking the injected mass by increasing the energizing time of the injector

leads to a longer burning duration and a performance loss of 1.8%

-10 0 10 20 30

Pi = 44.0 kW

Pi = 38.9 kW (D 11,8%) Pi = 43.3 kW (D 1,8%)

-10 0 10 20 30

11.1 °CA ATDC 11.0 °CA ATDC 12.0 °CA ATDC

cd = 0.88 (216 mg)

cd = 0.70 (192 mg) cd = 0.70 (216 mg), ET

Longer energizing time can track the power (increasing fuel consumption);

the BR50% changes slightly more

-10 0 10 20 30

Pi = 44.0 kW

Pi = 38.9 kW (D 11,8%) Pi = 43.3 kW (D 1,8%) Pi = 44.0 kW

-10 0 10 20 30

12.2 °CA ATDC

cd = 0.88 (216 mg)

cd = 0.70 (192 mg) cd = 0.70 (216 mg), ET cd = 0.70 (220 mg), ET , Pi = konst.

The same BR50% can be realized by an earlier injection start (fuel

consumption decreases)

Pi = 44.0 kW

Pi = 38.9 kW (D 11,8%) Pi = 43.3 kW (D 1,8%) Pi = 44.0 kW Pi = 44.0 kW

-10 0 10 20 30

12.2 °CA ATDC 11.1 °CA ATDC

cd = 0.88 (216 mg)

cd = 0.70 (219 mg), ET , Pi = BR50% = const.

Tracking the injected mass by increasing the rail pressure leads to a similar injection

and burning rate compared to the original cd value

Compensation of the lower cd value by increasing the rail pressure is more efficient

(0.9%) than increasing the control duration

-10 0 10 20 30

Pi = 44.0 kW

Pi = 43.7 kW (D 0,9%)

-10 0 10 20 30

cd = 0.88 (216 mg)

cd = 0.70 (219 mg), ET , Pi = BR50% = const. cd = 0.70 (216 mg), pRail

A higher increase of the rail pressure leads to the same power

-10 0 10 20 30

Pi = 44.0 kW

Pi = 43.7 kW (D 0,9%) Pi = 44.0 kW

-10 0 10 20 30

12.2 °CA ATDC 11.1 °CA ATDC 10.8 °CA ATDC 10.8 °CA ATDC

cd = 0.88 (216 mg)

cd = 0.70 (219 mg), ET , Pi = BR50% = const. cd = 0.70 (216 mg), pRail cd = 0.70 (219 mg), pRail , Pi = konst.

Delaying the beginning of the injection leads to the same BR50%

-10 0 10 20 30

Pi = 44.0 kW

Pi = 43.7 kW (D 0,9%) Pi = 44.0 kW Pi = 44.0 kW

-10 0 10 20 30

12.2 °CA ATDC 11.1 °CA ATDC 10.8 °CA ATDC 10.8 °CA ATDC

11.1 °CA ATDC

cd = 0.88 (216 mg)

cd = 0.70 (219 mg), ET , Pi = BR50% = const. cd = 0.70 (216 mg), pRail cd = 0.70 (219 mg), pRail , Pi = konst. cd = 0.70 (219 mg), pRail , Pi = BR50% = const.

Conclusion

By coupling a detailed 1D injector model and the IAV combustion model, it was

possible to analyse the influence of changing important design parameters:

• Outlet diameter of the control chamber has a more sensitive influence on the

combustion than the inlet diameter

• Changing the cd value of the nozzles shows only influences on the main injection

• Tracking the rail pressure for compensating the injected mass while the cd value

decreases is more efficient than increasing the control duration (constant power)

• Coupling the hydraulic and combustion 1D simulation represents an efficient tool

for the developing process of injection systems and burning processes.

• A detailed injector model could be very helpful, to simulate the real combustion

behaviour e.g. at multiple injection operation.

Thank you very much!

Dr.- Ing. Dennis Backofen

IAV GmbH

Nordhoffstraße 5, 38518 Gifhorn

Telefon: +49 5371 805-1587

dennis.backofen@iav.de

Model-based Calibration using Coupled Hydraulic and ... · Combustion Injection and mixture...

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