Clean water is crucial in hydropower, as sediments such as rock, gravel, sand, and clay can damage turbines, leading to costly maintenance. While the majority of research focuses on suspended sediment, cobbles and stones with diameters of approximately 5-10 cm can also pass through trash racks and potentially reach the turbine section, which is undesirable. Many hydropower tunnels in Norway are excavated using drilling methods, making them susceptible to rock failure within the tunnels. Large pieces of rock can travel downstream toward the turbines, posing additional risks. For optimal system design, it is essential to understand the incipient motion of large particle sediment, but current literature lacks accurate approaches to calculate this.
The main goal of this master’s thesis is to conduct hydrodynamics analyses, specifically to investigate the lift effect under various hydraulic boundary conditions in pressurized flow. In this analysis, the shape of the rocks or cobbles will be simplified to cubes or rectangular prisms, and it will be conducted on a single sample. This thesis will extend the scope of the current PhD project, which investigates the incipient motion of large particle sediment in free-surface flow. The observed data will be presented to Statkraft.
The experiment can be conducted either numerically using OpenFOAM or physically in the experimental flume at the Norwegian Hydrotechnical Laboratory, NTNU, Trondheim.