New Publication: Vortex Breakdown in a Hydropower Turbine Draft Tube

The study investigates the formation of the helical vortex rope in a Francis turbine draft tube from the perspective of vortex breakdown. Using a simplified laminar-flow setting, the work shows that the vortex rope emerges from an axisymmetric baseflow through a supercritical Hopf bifurcation. It further reveals subcritical solutions and hysteresis at partial-load conditions, as well as the formation and subsequent destruction of an axial recirculation bubble associated with the emergence of the helical vortex rope. As the flow discharge is increased toward nominal turbine load, the steady solution branch undergoes a transcritical bifurcation at finite Reynolds number.

The findings provide new insight into the bifurcation dynamics underlying vortex breakdown and vortex-rope formation in hydropower turbine flows.

Congratulations to Artur and Eunok on the publication!