Optical Techniques in Gasoline Engine Performance and
Emissions Development
Injector Spray Visualisation
Denis Gill, Wolfgang Krankenedl, DEC
Ernst Winklhofer
20.03.15
Optical Techniques in Gasoline Engine Performance and Emissions
Development
Injector Spray Visualisation
Contents
Introduction
■
Spray Box
■
Direct Injection (GDI)
■
■
Spray Visualization
■
■
Penetration, Spray Angle, Bend Angle
Patternator (Spray Distribution)
Drop Sizing (Malvern)
■
■
Injector Dribble
Optical Techniques in Gasoline Engine Performance and Emissions
Development
Injector Spray Visualisation
Introduction
•  Direct gasoline injection engines rely on their spray direction and
formation for good mixing.
•  Using video techniques into spray boxes, the spray form and
movement can be assessed, allowing injectors to be compared
and their properties analysed.
Spray Chamber - Description
Boundary Conditions
Results:
Rail pressure:
Variable - up to 500bar
Overall Structure
Chamber pressure:
Variable - from 0.3 to 11bar abs.
Spray Quality
Test fuel:
n - Heptan
Spray Develoment
Test fuel temperature:
20°C
After injections
Temperature in chamber:
Ambient (approx. 20°C) not
variable
Injection duration:
Variable
View:
Front and side
Size of observation window :
180*180*180 mm.
Set-Up
Compressed Air / Nitrogen
Fuel Supply
Cross Sectional View
Scavenging Air Inlet
Injector
Flow Straightener
Fuel
Supply
Observation
Chamber
Injector
Mounting
Carbon
Filter
Quartz
Windows
Observation Area
Vacuum
Pump
Air
Throttle Valve
Fuel
Water
Bypass Valve
Water
Digital Video System
Experimental Setup for GDI Spray Analysis
Injector
Spray Observation
Chamber
Stroboscope
Stroboscope
Digital
CCDCamera
Light Unit
VisioScope
Digital Engine
Video System
Optical Techniques in Gasoline Engine Performance and Emissions
Development
Injector Spray Visualisation – Spray Observation Chamber
Optical Techniques in Gasoline Engine Performance and Emissions
Development
Injector Spray Visualisation– Spray Observation Chamber
Optical Techniques in Gasoline Engine Performance and Emissions
Development
Injector Spray Visualisation
Contents
Introduction
■
Spray Box
■
Direct Injection (GDI)
■
■
Spray Visualization
■
■
Penetration, Spray Angle, Bend Angle
Patternator (Spray Distribution)
Drop Sizing (Malvern)
■
■
Injector Dribble
Optical Techniques in Gasoline Engine Performance
and Emissions Development
GDI Injectors
Connector below
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Fuel Pressure: 200bar;
Spray Visualisation
Pulse Duration: 1.5ms
Connector - rear
Connector - left
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Injector Spray Visualisation
0.2ms
0.5ms
connector behind
100bar; 1.5ms
0.2ms
0.5ms
connector right
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Injector Spray Visualisation
1.0ms
1.5ms
connector behind
100bar; 1.5ms
1.0ms
1.5ms
connector right
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Injector Spray Visualisation
100bar; 1.5ms
2.0ms
2.0ms
Optical Techniques in Gasoline Engine Performance
and Emissions Development
Injector Spray Visualisation
AVL Visioscope Software
Software allowing to visualize, post-process and export recorded data.
100% In-House development.
Extended library of image post-processing functions (see below)
Automatic assessment of penetration, spray angle, bend angle
Results:
Spray Penetration
Spray Stability/Repeatability
Probablity Distribution
Overlay Image
Trace iso-line
Colour invert
Example of results obtained thanks to AVL visioscope software
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Injector Spray Visualisation
Averaged Pictures
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Injector Spray Visualisation
Statistical Distribution of Fuel Concentration in %
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Injector Spray Visualisation
Definition of Spray Geometry Characteristic Numbers
Spray Angle
Bend Angle
Axial Penetration
Lateral extension
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Injector Spray Visualisation
Penetration
70
View 1
View 2
65
60
55
50
Penetration [mm]
45
40
35
30
25
20
15
10
5
0
0
2
4
6
8
10
CA [deg]
12
14
16
18
20
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Injector Spray Visualisation
Spray Angle
65
View 1
View 2
60
55
50
Spray Angle [deg]
45
40
35
30
25
20
15
10
5
0
0
2
4
6
8
10
CA [deg]
12
14
16
18
20
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Injector Spray Visualisation
Bend Angle
0.0
View 1
View 2
-2.5
-5.0
-7.5
Bend Angle [deg]
-10.0
-12.5
-15.0
-17.5
-20.0
-22.5
-25.0
-27.5
-30.0
0
2
4
6
8
10
CA [deg]
12
14
16
18
20
Optical Techniques in Gasoline Engine Performance and Emissions
Development
Injector Spray Visualisation
Contents
Introduction
■
Spray Box
■
Direct Injection (GDI)
■
■
Spray Visualization
■
■
Penetration, Spray Angle, Bend Angle
Patternator (Spray Distribution)
Drop Sizing (Malvern)
■
■
Injector Dribble
Optical Techniques in Gasoline Engine
Performance and Emissions Development
Patternator
Low resolution mechanical patternator
Results:
Spray Pattern
Spray Angles
SAE2715 does not recommend the
use of a mechanical patternator for DI
injector.
61 pipes
30
30
25
25
y [mm]
10
5
0
-5
-10
-15
-20
13
12
20
15
Relativ Mass [%]
15
-0.022
0.03
0.004
0.009
-0.026
0.056
-0.004
0.013
0.017
-0.013
0.009
0.013
1.488
4.288
0.034
0.03
2.198
1.071
0.275
0.017
0.013
11.01 11.944
0.034
0.022
0.314
1.548
0
0.026
0.009
0.938
0.396
0.056
0.009
0.292
6.477
0.052
0.03
0.034
3.213
1.071
0.017
0
12.219
8.073
0.366
0.06
0.955
6.486 10.288
0.017
-0.004
1.557
3.144
0.12
0.034
8.774
0.099
0.052
0.576
0.194
10
y [mm]
20
5
0
-5
-10
-15
-20
-25
-25
-30
-30
-30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30
x [mm]
∅ 4 mm
20
18
16
14
12
10
8
6
4
2
0
20
11
10
9
8
7
6
5
10
y [m
m]
-30 -25 -20 -15 -10 -5 0 5
x [mm]
10 15 20 25 30
0
-10
-20
-20 15
0
-10 -5
5
20
10 15
]
x [mm
4
3
2
1
0
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Patternator
Testing Conditions and Mass capture efficiency
20 mm distance between injector tip and patternator (Open pipes ends).
500 injections (100 bar fuel pressure into ambient at 1.5 ms PW) were performed corresponding to 60s
measuring time and 120 ms injection period.
At PW = 1.5ms and 100 bar fuel pressure , the dynamic flow is 9.24 mg/inj (see slide 16).
This leads to a total injected mass of 4.62g.
The sum of the masses found in the pipes of the patternator equal 2.33g.
The mass capture efficiency is therefore approx. equal to 50%.
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Patternator
Measurement Program
The table below shows the settings investigated :
Pulse widths
Absolute Fuel Pressure [bar]
100
Absolute Back-Pressure
[bar]
1
1.5 ms
Work Scope :
•  Installation of injector in spray chamber with high resolution mechanical mass patternator and verification
of alignment.
•  For the settings mentioned in the table below performance of a number of injection allowing the collection
of a significant amount of fuel in each of the 61 tubes of the AVL high resolution mechanical mass
patternator
•  Weighing the amount of fuel in each tube.
•  Post-processing.
Deliverables :
•  Fuel mass distribution and mass capture efficiency
Optical Techniques in Gasoline Engine
Performance and Emissions Development
Patternator
13
12
11
Relativ Mass [%]
10
20
16
12
8
4
0
20
9
8
7
6
5
10
20
4
10
3
0
-5
]
m
[m
5
y
-10
15
0
0
-1
5
-1
0
-2
-20
2
m
x [m
]
1
0
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Patternator
Views definition
30
0.13
25
0.12
20
0.11
15
0.1
10
0.09
0.08
y [mm]
5
0.07
0
0.06
-5
0.05
-10
0.04
-15
0.03
-20
0.02
0.01
-25
0
-30
-30
-25
-20
-15
-10
-5
0
x [mm]
5
10
15
View 1
20
25
30
View 2
Optical Techniques in Gasoline Engine
Performance and Emissions Development
Patternator
Optical Techniques in Gasoline Engine Performance and Emissions
Development
Injector Spray Visualisation
Contents
Introduction
■
Spray Box
■
Direct Injection (GDI)
■
■
Spray Visualization
■
■
Penetration, Spray Angle, Bend Angle
Patternator (Spray Distribution)
Drop Sizing (Malvern)
■
■
Injector Dribble
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Measurement Equipment - Malvern Spraytec STP2000
Main characteristics
Results
Laser
2 mW Helium-Neon laser (wave length 633 nm)
Beam expansion
10 mm
Characteristic diameters
Receiver
Fourier transformer lens f = 300 mm
Time history of characteristic diameters
Detection System
36 element log-spaced silicon diode detector array.
Size range
Measurement triggering
0.1 – 900 µm for 300 mm lens
Acquisition Rate
10kHz
Drop size distribution
Example of results
External Based on TTL input
Experimental set-up
Fuel
Average Derived Parameters
Injector
12 Apr 2011 - 10:29:42.9572
(average scatter, weighted)
PSA_Ford.smea\Z50_2000rpm - 12 Apr 2011\Averages\35bar_1,5ms_Z 50_10aus 1 1.psd
Sample : 35bar_1,5ms_Z 50_10aus
Event: 1 +0.0020 (s) :: Event: 100 +0.0200 (s)
Title
Average
Π
Min
Max
Trans (%)
Dv(10) (µm)
Dv(50) (µm)
Dv(90) (µm)
%V < 10µ (%)
D[4][3] (µm)
D[3][2] (µm)
Cv (PPM)
Span
Dv(0) (µm)
D[1][0] (µm)
D[2][0] (µm)
D[3][0] (µm)
4528 Records Averaged
86.8
12.42
23.23
42.53
3.693
25.7
20.72
16.11
1.296
6.274
13.97
15.32
16.94
5.347
2.937
4.514
7.72
2.297
4.854
4.335
6.501
0.1311
2.74
5.768
5.71
5.489
71.4
9.398
19.42
32.57
0
21.02
15.33
0.1177
0.5947
0.393
0.4532
1.041
3.379
100.0
39.09
56.28
94.6
11.71
61.65
53.34
45.85
1.642
23.4
46.33
47.93
49.61
Variation of the
Injector Position
Measuring volume
Receiver
Lens
He-Ne Laser
Detector
Array
Laser Beam
ø 10 mm
Vacuum
Pump
Air
Carbon
Filter
Device
Throttle Valve
Fuel
Water
Bypass Valve
Water
Meas.
Electr.
Computer
Monitor
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Measurement Equipment - Malvern Spraytec STP2000
30
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Measurement Equipment - Malvern Spraytec STP2000
Measuring Principle (Source SAEJ2715)
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Injector Variant Investigations
Physical and Chemical Characteristics of n-Heptane
Value / Region
Unit
Method
Density (15°C)
0.687 – 0.693
g/cm³
DIN 51757
Viscosity, kinematic (20°C)
0.641
mm²/s
ISO 3104
Surface tension (25°C)
19.7
mN/m
Wilhelmy Plate
Vapour Pressure (25°C)
6.1
kPa
Calculated (CONCAWE 2010a)
Boiling Point
93 – 100
°C
ASTM D1078
Ignition Temperature
204
°C
According to Lide (2005)
Melting Point
< -20
°C
Flame Point
-4
°C
According to Lide (2005)
Solubilty in Water (25°C)
2.5
mg/L
According to Lide (2005)
Distribution Coefficient in n-Octanol / Wasser
4.5
log pOW
According to Lide (2005)
Droplet size measurements, based in the principle of light scattering in the forward direction contain the risk of adulteration
caused by fuel vapourisation. Therefore, n- Heptan, which does not vapourise significantly, is used as test fluid.
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Measurement Programme
The box below shows an abstract of the binding commercial offer.
The table below shows the different settings investigated :
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Drop Size Distribution - Time History - 1
Results Description and Correlation to Spray Chamber Imaging
Pfuel = 100 bar, PW = 1.5 ms, Z = 30 and 50 mm
Fuel covers LD beam
(Z = 30 4.8°CA / 0.8 ms)
SOF (~ 1.6°CA / 0.25 ms)
SOL
Fuel covers LD beam
(Z = 50 7.2°CA / 1.2 ms)
EOF
0
1
2
3
4
Time [ms]
5
6
7
8
9
10
100
0.1
90
Transmission [%]
80
70
60
50
40
30
Min Trans at Z = 30 mm
(Z = 30 ~ 12°CA / 2 ms)
Transmission Z = 30 mm
20
Transmission Z = 50 mm
10
0
0
0
10
20
30
CA [deg]
40
50
N = 1000rpm
60
Min Trans at Z = 50 mm
(Z = 50 ~ 14.4°CA / 2.4 ms)
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Result Values Generated:
D (0,1) ; Dv(10)
10% of the measured droplet volume has a diameter below this value
D (0,5) ; Dv(50)
This is the average diameter of the droplets measured. i.e. 50% of the total
volume is made up of droplets smaller than this value and 50% are larger.
D (0,9) ; Dv (90)
90% of the measured droplet volume has a diameter less than this value.
D (3,2); SMD
This is a means of expressing the spray in terms of surface area produced
by the spray. It is the size of a drop having the same surface area to volume
ratio as all the total volume of all the drops to the total surface area of all the
drops
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Drop Size Distribution – cycle by cycle
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Drop Size Distribution – average
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Drop Size Distribution – average
Optical Techniques in Gasoline Engine Performance and Emissions
Development
Injector Spray Visualisation
Contents
Introduction
■
Spray Box
■
Direct Injection (GDI)
■
■
Spray Visualization
■
■
Penetration, Spray Angle, Bend Angle
Patternator (Spray Distribution)
Drop Sizing (Malvern)
■
■
Injector Dribble
Optical Techniques in Gasoline Engine Performance and
Emissions Development
Injector Spray Visualisation – Split Injection - Close Up
Spray Chamber Visualizations
Injector Tip
Overview Spray Characterization and Flow Characteristics
Summary
For Gasoline direct injection, the quality and form of the spray is
important for the mixture formation.
By means of optical techniques such as spray visualisation and laser
diffraction, we can assess the quality of an injector before engine
test, and ensure that the injector is suitable for its intended purpose.
The results of these tests can be used to support both CFD
modelling and the glass engine development work.
AVL – your reliable partner in powertrain development