These two videos are a result of the CFD simulation of flow in a Francis turbine, operating at deep part load (less than 35% of flow rate at the best efficiency point). It can be observed that the nature of the flow is unsteady, with a large swirl in the draft tube.
More information about the CFD simulation with the zonal LES turbulence model can be obtained in the paper:
Jošt, D., Škerlavaj, A., Morgut, M., Mežnar, P., and Nobile, E., 2015. Numerical simulation of flow in a high head Francis turbine with prediction of efficiency, rotor stator interaction and vortex structures in the draft tube. Journal of Physics: Conference Series 579(1), 012006. doi:10.1088/1742-6596/579/1/012006