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Design engineer calls on TrendCapture to help fish swim downstream

April 2011

Using a digital multimeter

Greg Wagner with a hydroelectric dam model in the background. Greg Wagner, Design Engineer Iowa Institute of Hydraulic Research (IIHR) - College of Engineering University of Iowa,Iowa City, Iowa (Photo courtesy of Greg Wagner.)

Design Engineer Greg Wagner, from the IIHR unit of the University of Iowa’s College of Engineering, uses the TrendCapture feature in the Fluke 287 True RMS Electronics Logging Multimeter to support fish passage research. His submission regarding that application was chosen as Runner Up for the February Fluke News Plus contest. He won a Fluke 1000 A AC/DC True RMS Clamp Meter.

Fish passage research is just one of many research projects in hydraulics and fluid mechanics conducted by the Iowa Institute of Hydraulic Research (IIHR) unit of the College of Engineering at the University of Iowa. One of the nation’s oldest and most respected fluids research and engineering laboratories, IIHR offers a combination of theoretical training and hands-on engineering practice that attracts students from all over the world.

Wagner designs and supports custom instrumentation for IIHR. One tool used extensively in the unit’s hydraulic models is the Acoustic Doppler Velocimeter (ADV), which uses the speed of sound to measure the velocity of the water and the direction it flows. The results are used, among other things, to assess the impact of changes in hydroelectric dams on fish passage downstream.

To assure the most accurate ADV readings, the equipment needs to register the actual temperature of the water. Since IIHR’s hydraulic models span large areas of the laboratory with varying water depths and heated and unheated environments, the water temperature can vary widely from one end to the other. Wagner explains how he uses the TrendCapture feature in the Fluke 287 DMM to determine when the water temperature is stable enough to get consistent ADV results:

“When the hydraulic model hasn’t been running for a few days the water temperature varies widely in different sections. The ADV is dependent on temperature because the speed of sound changes with temperature. Therefore it’s critical that the water temperature in the hydraulic model be stable. When we start up the pump to get the water moving, we use the TrendCapture feature on the Fluke 287 to record the fluctuations in water temperature and determine when the temperature has stabilized. Once we know the water is uniformly distributed in terms of temperature we can quickly see how the water temperature correlates to the ADV results.”

In this issue also you can read about the two Best of Show winners for the February Fluke News Plus contest.