POD used as a filtering method
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Slide 1 Den Haag September 2007 POD used as a filtering method Example: Poorly seeded Helium Jet Raw Images Subtract the Mean image Calculated Instantaneou s velocity vectors Decompose the flow, and preserve the highest energy levels (Here upper 10%)
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Decompose the flow, and preserve the highest energy levels (Here upper 10%). Calculated Instantaneous velocity vectors. Subtract the Mean image. Raw Images. POD used as a filtering method. Example: Poorly seeded Helium Jet. Holes in gappy dataset - PowerPoint PPT Presentation
Transcript of POD used as a filtering method
Slide 1 Den Haag September 2007
POD used as a filtering methodExample: Poorly seeded Helium Jet
Raw ImagesSubtract the Mean image
Calculated Instantaneous
velocity vectors
Decompose the flow, and preserve the highest energy levels (Here
upper 10%)
Slide 2 Den Haag September 2007
POD as filtering• Holes in gappy dataset
• Poorly seeded TR measurements often have that
VectorsImage POD Projection (90% of energy)
Slide 3 Den Haag September 2007
POD as filtering• Example – a jet where the surrounding air has not been seeded
Slide 4 Den Haag September 2007
EndoscopesSetup for 3D PIV
Two different endoscopes:
-Normal end
-45 slanted end
Slide 5 Den Haag September 2007
Endoscopic light sheet optics
Slide 6 Den Haag September 2007
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ResultsRotor - Position 1in-plane velocity
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Rotor - Position 1out-of--plane velocity
Rotor-Position 1Instantaneous Vortivcity
More details about the measurements in a transonic test turbine can be found in: Lang et al., "Stereoscopic particle image velocimetry in a transonic turbine stage", Experiments in Fluids 32, 2002, pp 700-709
Slide 7 Den Haag September 2007
• Slow, low-turbulentwater flow
• 60 µm polyamide particles
• 20W AR-Ion laser w. scanning mirror
• NanoSense camera
• Frame rate ~100 Hz
• Measuring distance 3.7m(1.2 m in water)
• Measuring area820 x 1000 mm
I.e. almost 1 m2 !!!
Large area TR-PIV
Slide 8 Den Haag September 2007
Understanding tip vortices in detailswith PIV measurements in water
x/b=6.80.2 nm
K. & C. Huenecke, Airbus
x/b=30.00.9 nm
x/b=63.02.0 nm
1962 CTA measurements in open air,waiting for the fly-by of the aircraft
Wingtip vortices, then and now
Slide 9 Den Haag September 2007
Laser housing on vertical traverse
1 - 6 m down
10 m laserumbilical
Power supplyon platformTowed
aircraftmodel
Cross section of HSVA tank
Submerged PIV for large towing tank
Slide 10 Den Haag September 2007
Vector Field Vorticity
Click on the picture
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Trajectory of the Vortex Core
y-z
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Vector Field and Velocity Magnitude
Click on the picture
Slide 13 Den Haag September 2007
Thank you!
