The average age of Norwegian hydro power plants are 45 year, and many show sign of fatigue and needs to be constantly maintained or refurbished. Additionally, some power plants in Norway has experienced failures when installing new Francis turbines. The main problem is the formation of cracks in the turbine runner originating from high pressure amplitudes and/or resonance. The Norwegian hydropower industry have therefore addressed the risk of failure as a problem and want to see that the turbine manufacturers are capable of delivering turbines without formation of cracks before the end of the lifetime. Altogether, 9 utility companies, 4 turbine manufacturers, 3 consultants, Energi Norge, NVKS and NTNU are partners in this project.

The main challenges for this project is to carry out model turbine measurements, which can be utilized to build a procedure for the numerical analysis of the Fluid-Structure Interaction (FSI) on high head Francis turbines. This procedure will reduce the risk for resonance and breakdown in future installation of high head turbines.

The project will work with simplified models for the turbine runner and a complete Francis turbine model, and thorough measurements combined with FSI-analysis will be carried out. The flow conditions in a Francis turbine runner will be simplified and isolated in a blade cascade and the material properties such as the natural frequency of the runner will be tested with simplified geometry. The model of the Francis turbines at Tokke power plant will be utilized for the measurements. Here, steady state and transient operation of the turbine will be investigated. The main challenge is to carry out good measurements of the pressure and stress in the runner. The measurements from the Tokke model turbine will be provided to other researchers through the Francis-99 workshops. The Francis-99 workshops aim to determine the state of the art of high head Francis turbine simulations (flow and structure) under steady and transient operating conditions as well as promote their development and knowledge dissemination openly.

The budget for this project is approximately NOK 16 million. 

Project period: January 2016 - December 2019

Onboard measurements in a Francis model turbine, including measurements in the vaneless space and between the guide vanes. Waterpower Laboratory, NTNU.