Automatic Design of Hydropower Flows: The Draft Tube

Abstract

The focus is set on a redesign of an existing draft tube by usage of an automated optimisation based on CFD calculations. By this method a design can be predicted in terms of a predefined objective function, here the pressure recovery factor. The design parameters used are based on spline-functions that are set under certain restrictions. One is that the new design should fit into the old one. The optimisation is performed with the Response Surface Method (RSM) implemented on the commercial code iSIGHT6.0. The flow simulations are carried out with the commercial code, CFX4, with the standard k-ε turbulence model and with boundary conditions based on detailed experimental data. With this set-up and the chosen parameterisation the highest value is found at the edge of the design space allowing for further improvements.