Experimental observation of the precessing-vortex-core reconnection phenomenon in a combined-flow turbine

Abstract

Some results of experimental studies of the vortex-core reconnection phenomenon in the flowthrough duct of a combined-flow turbine were presented. The studies were performed on a medium-scale hydrodynamic test bench, the design of which was maximally similar to real hydroturbines. Using high-speed recording in a regime with a 75% load in a suction-pipe diffuser, the reconnection of a precessing vortex-core with detachment of vortex rings was observed. Aperiodic pressure surges due to the reconnection of a vortex and the formation of vortex rings were experimentally detected.