flow measurements of power plant discharges using thermal imaging david admiraalunl ce john...
Post on 15-Jan-2016
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Flow Measurements of Flow Measurements of Power Plant Discharges Power Plant Discharges Using Thermal ImagingUsing Thermal Imaging
David AdmiraalDavid Admiraal UNL UNL CECEJohn StansburyJohn Stansbury UNL UNL CECEDonald RundquistDonald Rundquist UNL UNL SNRSNRDennis AlexanderDennis AlexanderUNL EEUNL EEJunke GuoJunke Guo UNL UNL CECEMike DrainMike DrainCNPPIDCNPPID
Laboratory Measurements of Surface Velocity in a Flume
• 70 cm Wide, 10 m Long Flume• Five Discharges• Five Depths• Four Seeding Rates• Discharge Measured Independently with Weir• Surface Temperature Measured with Thermal Imaging Camera Mounted 2 m Above Water Surface
Laboratory Measurements of Surface Velocity in a Flume
Sample AVI of Seeded Flow
Laboratory Experimental Results
Flow Seeded with Hot Water
Time 1: 0.000 s Time 2: 0.264 s
Velocity Vector Determination By Tracking Thermal Structures
Two Algorithms for Seeded Flow
Unaltered Image Contouring of Thermal Gradients
By Filtering or manipulating the thermal data we can improve vector calculations (note improvement in vector
calculation for the image on the right)
Discharge Calculation Results Using Surface Velocities From Contoured
Images Shown in Previous Slide
•Average Surface Velocity Measured with Thermal Camera: 0.309 ft/s• Depth-Averaged Velocity Calculated using
Power Law: 0.271 ft/s• Discharge Computed using Depth-Averaged
Velocity and Flow Area: 0.397 cfs• Discharge Measured with Weir: 0.378 cfs• Percent Difference between Calculated and
Measured Discharge: 5%
Laboratory Experimental Results
Unseeded Flow
Time 1: 0.000 s Time 2: 0.264 s
Note that images have been manipulated to show that there is observable motion of structures. Some of the
structures have been circled in the images.
Velocity Vector Determination By Tracking Thermal Structures
One Algorithm for Unseeded Flow
Thermal Gradients have been Contoured and Images have been
Filtered to Reduce Noise
Contouring and filtering vastly improves vector results, but many of the vectors are still biased to zero because of the correlation algorithm. We are currently attempting a new
algorithm called Minimum Quadratic Difference (MQD)
Summary
• It is feasible to accurately measure surface velocity in seeded flows
• It appears to be feasible to accurately measure surface velocity in unseeded flows,
but a more robust algorithm will be important to reduce the effects of noise• Choice of image interrogation algorithms and
filtering can improve velocity measurement results
Sample of Aerial Measurements at Gerald Gentleman Station Cooling Pond
Field Measurements of Surface Velocity in GGS Cooling Pond
Sample AVI