Development of the pressure-time method for low-head machines

Hydropower is a renewable energy source that can regulate fluctuations in the electricity grid. Many hydropower plants were built decades ago and now need major upgrades. Turbine efficiency is an important factor to verify before and after a turbine upgrade. In most methods for this purpose, the flow rate must be determined.

The pressure-time method is an efficiency measurement method and is relatively cheap and easy to apply compared to other methods. It estimates the flow rate by integrating the measured differential pressure and the pressure loss between two cross-sections in a water system during the deceleration of the fluid mass when the flow is throttled by a valve or guide vanes. The pressure-time method has limitations specified in standard IEC-60041, which makes it difficult to apply to low head turbines due to the short water paths where the flow field develops. The main focus of this project is to improve the accuracy of the pressure-time method and extend its application to low head turbines. Numerical simulations and an experimental study are carried out. A laboratory setup is designed and built to test the pressure-time method. The method is tested on cases with tubes of variable cross-section, bend and shorter length than what IEC-60041 recommends.