Velocity measurements of Sprays
En’Urga Inc.1201 Cumberland Ave., West Lafayette, IN 47906
Background
Several instruments available on the market
Single point measurements obtained using LDV, PDA, hot wire anemometry
For planar velocities, PIV is the most commonly used instrument (requires capture of images of
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1201 Cumberland Avenue, West Lafayette, IN 47906
used instrument (requires capture of images of individual particles)
Image correlation velocimetry does not require resolution of individual particles, but requires distinct patterns
Basic Arrangement
High speed camera
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1201 Cumberland Avenue, West Lafayette, IN 47906
Uniform background light
High speed camera
Spray
An Overview of Process Flow
Install camera with diffuse light source
Configure camera f-stop and focus
Calibrate millimeters to pixels conversion
Record reference frames with no spray
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1201 Cumberland Avenue, West Lafayette, IN 47906
Record reference frames with no spray
Configure settings in SPIV
Processing and post-processing
Statistical Pattern Imaging Velocimetry
Does not rely on capturing individual particles or distinct patterns
Requires large ensemble of images
Computes statistical correlation between patterns over the entire pixel range
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1201 Cumberland Avenue, West Lafayette, IN 47906
patterns over the entire pixel range
Image correlation velocimetry does not require resolution of individual particles
Sample Results (GDI Injector)
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1201 Cumberland Avenue, West Lafayette, IN 47906
Full Flow Field Mean Axial Velocity of GDI Injector
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1201 Cumberland Avenue, West Lafayette, IN 47906
Comparison of our SPIV with PDA
0
25
50
75
100
50
75
100
20 MPa, PDA 20 MPa, SPIV 12 MPa, SPIV 12 MPa, PDA 12 MPa, CFD
x = 5 mm
Axia
l ve
locity (m
/s)
x = 30 mm
GDI injector
PDA fails near injector due to high obscuration
10000 Hz camera
Good agreement at
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1201 Cumberland Avenue, West Lafayette, IN 47906
0 5 10 15 20 25 30 35
0
20
40
60
80
0
25
x = 50 mm
Distance (mm)
Axia
l ve
locity (m
/s)
Good agreement at lower positions
Full planar axial velocity available
Example results with low spray opacity
Raw DataProcessed Velocimetry Results
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1201 Cumberland Avenue, West Lafayette, IN 47906
Signal to noise of 1.1
Example results ensemble averaging 4ms spray bursts
E = 5 eventsE = 1 events
E = 10 events E = 30 events
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1201 Cumberland Avenue, West Lafayette, IN 47906
E = 10 events E = 30 events
Questions?
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1201 Cumberland Avenue, West Lafayette, IN 47906