An alternative approach to the Von Karman vortex problem in modern hydraulic turbines

The usual method of dealing with resonance resulting from Von Karman vortex shedding from the trailing edges of hydraulic turbine components is to calculate the shedding frequency of the vortex street using a suitable Strouhal Number, and compare this frequency with the natural frequencies of the component. If the natural frequency is higher than the highest shedding frequency (say by 30 per cent) then the component can be considered safe from vortex-induced resonance. In this paper the authors review traditional approaches to the problem and detail the advantages of adopting a new approach in the context of modern turbine design features.