CHANNEL DISCHARGE MEASUREMENT BY THERMODILUTION1

ABSTRACT: An investigation was conducted to determine the feasibility of applying thermodilution technology to discharge measurements in small open channels. A series of tests were performed in which the time-temperature dilution curves were recorded and analyzed. The independent variables included the channel discharge, the injectate drop height, the volume of tracer, and the mixing distance. Flows ranged from 0.67 cfs to 2.45 cfs with Froude numbers less than 0.30. The results indicated that the thermodilution technique is a feasible method for discharge measurement. It was determined that a heat content, 1°, of 40°C provides a design criteria in which the mixing distance was related to the flow depth and discharge in a rectangular channel. An empirical expression was derived to determine the approximate mixing distance as a function of the flow depth.