Developing a traversing acoustic discharge measurement technique for the performance testing of low-head hydroelectric turbines

Abstract

The efficient operation of a hydroelectric generating plant requires an accurate definition of the performance relationships for each turbine-generator unit. Of the information obtained during performance testing, discharge is the most difficult to measure accurately. Acoustic transit-time velocity measurement technology is applied herein to obtain more accurate discharge measurements than current velocity - area method practices. The technique proposed involves continuously traversing a number of acoustic paths, each providing a chordal average velocity measurement, across the turbine intake to obtain a complete integration of the complex velocity profile typical of low-head hydroelectric plants. Data from hydraulic laboratory testing of a single acoustic cell were compared with known flow rates to assess the accuracy and repeatability of the proposed discharge measurement technique. A range of continuous traverse rates was evaluated. The results indicate that the proposed continuous traversing acoustic discharge meter (TADM) can provide efficient, accurate (1-2% error), and repeatable discharge measurements.Key words: turbine, performance testing, acoustic discharge measurement, traversing.