Analytical solutions using the thermodynamic efficiency method for absolute flow measurement

Manufacturers of large-scale hydraulic machines face high liquidated damages if they cannot meet performance guarantees. Accurate determination of efficiency, power and flow is therefore of great interest. For plants exceeding heads of 100 m, the thermodynamic method is the standard approach. We present a mathematical refinement that uses additional power measurements to achieve an analytical solution for the flow. Under excellent thermal conditions, the measurement uncertainty is lower than that associated with other methods of absolute flow measurement at medium heads. For higher heads an even lower uncertainty can be expected.