ABSTRACT
ABSTRACT: Piano Key Weirs (PKW) are new cost-effective free-flow spillways, designed to substantially increase the discharge capacity of dams. Four have alreadybeen achievedonEDFdams to meet the new hydrology requirements. However, their structure involves a lot of geometrical parameters and the hydraulic behaviour is complex. A better understanding of flow patterns in PKW and an optimisation of their shape are becoming real issues. A 3D numerical model has been developed at EDF on the CFD-Software Flow-3D®. Calibrated on the physical model results of Lempérière et al. (2003) and validated on other EDF physical model studies data, the numerical model has been used to carry out a sensitivity analysis for geometrical parameters of PKW. Several geometrical parameters (alveoli width ratios, deflectors, etc.) have been tested on the PKW model A of Lempérière et al. (2003) for a large range of flowrates. This paper presents the results of the sensitivity analysis and makes recommendations for these parameters according to the results of more than a hundred numerical simulations. These optima are likely to be valid only for the given configuration and dimensions of the PKW model A, but they give a first idea of the influence of the tested parameters.
