Hydraulic effects of an inflatable rubber weir located over a wes original spillway profile: experimental and cfd approaches.

Sarai Díaz, Javier González

Tuesday 30 june 2015

9:45 - 10:00h at Africa (level 0)

Themes: (T) Water engineering, (ST) Computational methods

Parallel session: 4F. Engineering - Instrumentation

The behavior of an inflatable rubber weir is highly dependent on the flow conditions, the membrane properties and its inner pressure. These structures can therefore adopt different shapes that interfere with the flow, adapting themselves to a wide variety of scenarios. This flexibility can be of interest in certain situations, such as in reservoirs where an increase in the water storage capacity is required without compromising the weir’s response in case of flooding. The objective of this study is then to analyze the effects of locating an inflatable rubber weir over a WES original spillway profile, studying how this additional piece might affect the main structure and its hydraulic operation. Two approaches are adopted to undertake this study: an experimental and a CFD model. The experimental device consists on a down-scale weir profile on top of which a rubber weir (EPDM 0,4 mm thick) is placed. This structure is controlled by an air valve, which allows to achieve different levels of inflation that are tested for various upstream levels, measuring the pressure evolution of the flow along the spillway and the associated discharge coefficients. Additionally, a CFD model (working with a k-_ model of turbulence and a homogeneous multiphase flow model) of the most critical positions of the inflatable weir allows to explore the changes experimented by the flow as a result of its location over the spillway. This study proves that important changes take place in terms of pressure upstream and downstream the inflatable weir when located over a spillway profile, and highlights the importance of aeration. Good agreement is found between experimental and numerical results. The pressure distribution variation leads to a reduction of the flow evacuated in the spillway as a function of the waterhead.