CFD modeling of two-phase flow of a spillway chute aerator of large width

Abstract

An aerator is frequently used to prevent cavitation damages in high-velocity spillways. To understand its characteristics, one often resorts to physical model tests. To complement physical model tests, computation fluid dynamics simulations are used to determine water–air flow behaviors. With Bergeforsen's 35 m wide aerator, numerical modeling has been performed to evaluate its performance and improve its configuration. The parameters of interest include spillway discharge capacity, air entrainment rate, duct subpressure and air concentration in the aerated flow. The simulated discharge capacity agrees reasonably with experimental data. Due to the larger chute width, empirical formulas do not reasonably predict the air demand. To provide the air required by the aerator, its distribution in the cavity must be guaranteed. We thus looked into the air supply system and the air flux in the cavity to improve the aerator function. Larger vent openings in the middle of the chute are preferable for large-width aerators.

Keywords:

• spillway
• chute aerator
• air demand
• air–water flow
• CFD
• subpressure

Acknowledgements

The authors are indebted to Mr Cristian Andersson and Ms Sara Sandberg of SVC for project co-ordinations. The authors would also like to thank the four anonymous reviewers for their valuable comments, which improved the quality of the paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Penghua Teng is a Ph.D. student with Hydraulic Engineering, Royal Institute of Technology (KTH), Stockholm. He received a BSc degree from Changan University and a MSc degree from Northwestern Polytechnical University, Xi'an. His present research focuses on water–air two-phase flow phenomena in spillway structures, in which both computational methods and experiments are involved.

James Yang obtained his Licentiate and Ph.D. degree from Royal Institute of Technology (KTH), Stockholm. He is a professor of hydraulic design at KTH and a R&D principal with the Vattenfall Group. The majority of his research and consulting activities are in the areas of dam safety and hydraulics in conduits, open channels and porous media. He is a member of the ICOLD Committee on Hydraulics for Dams.