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

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

Článek WoS

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

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

swirling flow; vortex rope; passive flow control

swirling flow; vortex rope; passive flow control

URBAN, O.; KURKOVÁ, M.; POCHYLÝ, F.

2023

22.12.2022

AIP Publishing

1070-6631

PHYSICS OF FLUIDS

34

12

Spojené státy americké

1

18

18

https://aip.scitation.org/doi/full/10.1063/5.0128029