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