Multidisciplinary optimization of an axial turbine

Abstract The results of three different optimization setups for an axial propeller turbine consisting of a guide vane, a runner and a draft tube are presented. The first setup only contains the efficiency as objective and the design head as a constraint. In the second setup, the minimization of the cavitation volume is added as a further objective while in the third, the compliance with a permissible stress is included as an additional constraint. Three operating points are simulated during the optimization. Comparing the results of the first two setups, the minimization of the cavitation volume leads to a lower plant efficiency at all operating points. Including structural mechanical aspects results in a further decrease of the plant efficiency at all operating points. Nevertheless, none of the best individuals from the setups have a maximum von Mises stress below the permissible stress without taking the structural stress limits into account. This points out the importance of considering both, structural as well as fluid mechanical aspects in the optimization process of hydraulic machines.