Experimental and numerical study of a chute spillway

Abstract

This paper presents a combined approach, including CFD numerical and scale physical modelling, to address the hydraulic behavior of the spillway of a dam. The spillway studied is an open channel flow which crosses the right abutment of the dam, it runs in that part of the hillside and it has three separate spans controlled by Taintor Gates of 9.5 x 6.8 m. The design flow of the spillway is 1,648.5 m3/s and the verification flow is 1,885.4 m3/s. Choosing and setting the spillway different forms, such as feeding, piers, gates positioning, curve at the beginning of the chute, spans convergence, height of the walls and bucket type, was performed after analyzing numerous options and through numerical methods in fluid computational hydraulics. The software used was FLOW 3D, it solves Navier Stokes equations by finite differences. The different options are now being verified on a physical scale model in the Laboratório Nacional de Engenharia Civil (LNEC). The use of numerical methods in fluid computational hydraulics is very useful when used by the designer in combination with the physical modelling. It allows analysing different options until getting hydraulically optimal solutions which can be tested in a laboratory. This method provides undisputed advantages in the technical field as well as on the use of time and resources. In this presentation there are a variety of approaches created by fluid computational hydraulics in relation to the spillway dam. It is analysed the hydraulic behaviour of the different options and the results of numeric model are compared with the obtained in tests carried out in the physical scale model.