Abstract
The investigation of a (complete) failure of a penstock is part of a global risk analysis of a high-pressure hydropower plant. The paper summarizes basic facts about the reason for such events, the process of development and possible ways to reduce the damage caused by such a hazard. In the second part possible modelling strategies for such failures are presented. Therefore, the commercial 1D numerical software WANDA is used and the results are compared with the basic Bernoulli equation. The critical part of such an investigation is that cavitation can occur based on the extreme acceleration of the water caused by the local reduction of the pressure at the defect. The high speed of the water can also lead to further local head losses which exceed the normal values. To implement such effects in the numerical simulation, an adapted numerical model is presented, which uses control points in the hydraulic system to limit the reduction of the chosen boundary condition at the failure. All in all, this paper should present possible modelling concepts and highlight open research questions.