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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
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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 Poorly seeded TR measurements often have that POD as filtering POD Projection (90% of energy) Vectors Image
Example – a jet where the surrounding air has not been seeded POD as filtering
Two different endoscopes: Normal end 45 slanted end EndoscopesSetup for 3D PIV
Results Rotor - Position 1in-plane velocity 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
Large area TR-PIV • 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 mmI.e. almost 1 m2 !!!
x/b=6.8 0.2 nm x/b=30.0 0.9 nm x/b=63.0 2.0 nm K. & C. Huenecke, Airbus Wingtip vortices, then and now Understanding tip vortices in details with PIV measurements in water 1962 CTA measurements in open air, waiting for the fly-by of the aircraft
Submerged PIV for large towing tank Cross section of HSVA tank Power supply on platform Towed aircraft model 10 m laser umbilical Laser housing on vertical traverse 1 - 6 m down
Vector Field Vorticity Click on the picture
Vector Field and Velocity Magnitude Click on the picture