Study on straight cavitating vortex dynamics generated due to increase in the axial flux of angular momentum

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en

The straight cavitating vortex develops in the discharge pipe geometry of the swirl device. The onset of such a vortex is due to the prevailing flux of angular momentum over the flux of axial momentum. In other words, the flow with a significant magnitude of non-dimensional swirl number is created. These flow conditions are well known for the centrifugal pump running in reverse (turbine) mode and might be dangerous for safe operation of small hydropower devices. For this purpose, the swirling device in the form of a rotating radial blade wheel, placed in the convergent geometry of the spiral case, is used for presented research. Although this vortex seems to be coherent and relatively stable in time, significant flow dynamics exists. The only thing ensuring the quasi-straight shape of the vortex is the constant radius of the discharge geometry domain. The aim of this study is to evaluate dynamics behavior of such vortex using the experimental data and CFD simulations. The pressure signal from measurement together with the high-speed camera record of the vortex movement are correlated with results from simulations. The vortex dynamics is examined through the proper orthogonal decomposition. The vortex identification methods are used for postprocessing of CFD data to verify detailed turbulent behavior of flow. Better understanding of this flow phenomena can serve for optimization of pumps as turbines largely used for energy recovery in water distribution networks.

cavitation; vortex; CFD; pump; turbine

2025-10-23

European Turbomachinery Society

Proceeding of the 16th European Conference on Turbomachinery Fluid dynamics & Thermodynamics

1–8

8