Numerical Simulation of Air–Water Two-Phase Flow on Stepped Spillways Behind X-Shaped Flaring Gate Piers under Very High Unit Discharge
| Autor: | David Vetsch, Robert M. Boes, Zongshi Dong, Junxing Wang, Guangming Tan |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
lcsh:Hydraulic engineering
Geography Planning and Development Flow (psychology) 0207 environmental engineering Stepped spillway stepped spillway 02 engineering and technology Aquatic Science Computational fluid dynamics 01 natural sciences Biochemistry 010305 fluids & plasmas cavitation erosion lcsh:Water supply for domestic and industrial purposes lcsh:TC1-978 0103 physical sciences 020701 environmental engineering Water Science and Technology lcsh:TD201-500 Spillway Computer simulation business.industry Mechanics X-shaped flaring gate piers self-aerated free-surface flow CFD Cavitation Environmental science Two-phase flow Air entrainment business |
| Zdroj: | Water, 11 (10) Water, Vol 11, Iss 10, p 1956 (2019) Water Volume 11 Issue 10 |
| ISSN: | 2073-4441 |
| DOI: | 10.3390/w11101956 |
| Popis: | Stepped spillways are commonly used under relatively low unit discharge, where cavitation pitting can be avoided by self-aerated flow. However, there are several dams in China with stepped spillways in combination with X-shaped flaring gate piers with unit design discharge considerably larger than specified in the available guidelines. Consequently, air&ndash water two-phase flow on stepped spillway behind X-shaped flaring gate piers under very high unit discharge was investigated using Computational Fluid Dynamics (CFD) simulations. The 3-D Reynolds-averaged Navier&ndash Stokes equations were solved, including sub-grid models for air entrainment, density evaluation, and drift-flux, to capture self-aerated free-surface flow over the spillway. The pressure on the vertical step faces was compared with laboratory data. In addition, the air&ndash water two-phase flow characteristics and prototype step failure of the simulated prototype spillway were analyzed based on the numerical results of velocity, pressure, and air concentration. Moreover, an optimized bottom-aeration was further studied. The results reveal that the involved models can predict the air concentration near the steps. The cavitation index at the stepped surface is below the threshold value, and the air concentration is insufficient under high unit discharges. Moreover, with the proposed optimization of the aerator air entrainment can be improved and thereby cavitation erosion risk can be reduced. |
| Databáze: | OpenAIRE |
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