Computer modeling of the stress state and reliability assessment of bolted connections of the rotor and runner of Kaplan turbines

Ensuring the trouble-free operation of hydroelectric power stations is an important element of the stability of the power grid. Hydraulic turbines are often used to regulate daily fluctuations in electricity consumption. It is the start/stop modes of the hydraulic unit that are the most dangerous and lead to the highest levels of mechanical stress. Therefore, the work is devoted to the development of detailed three-dimensional models for assessing the stress state of bolted connections of the impeller, and on their basis determining the stress state in different operating modes of the hydraulic unit. The similarity method based on known experimental data is used to determine the load acting on the bolted connection. Determination of the stress state is carried out using the finite element method. The developed three-dimensional detailed finite-element model takes into account the non-linear interaction between the connecting parts: the bolt, the shaft flange, and the impeller body. Determined stresses as a function of time, which occur during the start/stop of the hydraulic unit and are used to estimate the life (including the residual) of the bolted connection.