Comparison of Turbine Discharge Measured by Current Meters and Acoustic Scintillation Flow Meter at

Performance tests were conducted at Unit 22 at Hydro-Québec’s Laforge-2 plant between June 11 and 15, 1997. These tests included measurements of the discharge through the turbine using current meters. Simultaneous measurements were also taken in one bay of the intake with an Acoustic Scintillation Flow Meter (ASFM). The ASFM is a new instrument which offers unique advantages for measuring intake flows in low-head, short intake plants for which current meters have been the traditional and only effective method. It is non-intrusive, and its deployment in intake gate slots is straightforward, allowing data to be collected with a minimum of plant downtime. Laforge-2 is typical of large to medium-sized plants of that type: it is equipped with two 147 MW Kaplan turbines, each with a three-bay intake. The bays at the metering section are 19.7m high and 6.1m wide. The net head for the plant is 27.4m. The current metering used one hundred ninety measuring points in each bay, obtained using forty individual current meters mounted in four rows of 10 on a frame 4.6m high. The current meter rows were spaced 1.08m apart vertically. The inclination of the meters was controlled by a hydraulic adjustment system to align them with the flow. The ASFM transducer arrays were mounted on the same frame as the current meters in Bay 1, at the trailing (downstream) edge o