Flow Measurement Methods Applied to Hydro Power Plants

Efficiency and maximal power output are two of the most important goals to analyze in hydraulic turbines. Turbines normally operate in variable head conditions; therefore, tests to analyze performance are frequently realized for a selected number of power plant heads. Usually it is limited to three heads: low, medium and high. The efficiency of water turbines is most frequently expressed using the weighted average efficiency or arithmetic mean efficiency, calculated from the measured results in the examined heads. To perform the calculation of efficiency is necessary to know several parameters such as kinetic and potential energy of water due to the position, because of this is required to know the flow rate entering the turbine. The flow rate of water through the turbine (Q) is determined by the volume of water flowing in time unit. The measurement of this quantity is one of most difficult tasks in water turbine tests. Three basic methods of flow rate measurement and results of them will be presented in this chapter.