Power production from intermittent renewable energy resources, such as solar and wind, has increased in the past few decades, leading researchers and engineers to establish techniques to preserve a stable electrical grid. The flexibility and fast responsiveness of hydropower systems make them a reliable solution to balance the electrical grid. Consequently, hydraulic turbines are being used more frequently in transient operating modes to regulate the grid. Therefore, investigating the complex flow fields during such operation is essential to increase the reliability and life-time of future hydropower systems. The present work provides comprehensive numerical studies on the transient flow field of different hydraulic turbines model throughout the shutdown, startup, and load change. The flow-induced forces are used for structural analysis and lifetime assessment and for determing cost of operation.