A practical approach to use the thermodynamic efficiency method for flow measurements

The thermodynamic efficiency method represents the most accurate technique to measure the efficiency of hydraulic machines exceeding 1 kJ/kg of specific energy. On large-scale machines, it is common to use this method also to measure the discharge by simultaneous measurement of the mechanical power. This is either done iteratively or by the use of analytical solutions for simple test setups. We present here an extension of these analytical solutions to arbitrary test setups and conditions, which appear in practical applications. A sign convention has been introduced to harmonize relevant test codes, which deal with performance testing of hydraulic turbines and pumps, in the future.