Mitigation of swirling flow with a vortex rope by passive installations—Theory, simulations, and experiments

This work is focused on reduction of swirling in cases from hydraulic machinery and, thus, mitigation instabilities associated with flow. We study this problem analytically using the torque integral equation, numerically computational fluid dynamics (CFD) simulations, and experimentally a swirl generator that generates flow approximating draft tube hydro turbine operating at part load, featuring an unsteady spiral vortex—the vortex rope. The analytical description elucidates effect different installations circumferential velocity. Unconventional conical perforated targeting increasing dissipation were proposed tested. rather unsatisfactory results led to proposing fins placed unconventionally away wall, closer diffuser axis, which subsequently shown be able reliably suppress Their documented by analysis CFD including proper orthogonal decomposition as well experimental observations measurements.