Optimization and Computational Fluid Dynamics - Department of ...

Chapter 6
Numerical Optimization for Advanced
Turbomachinery Design
René A. Van den Braembussche
Abstract The multilevel-multidisciplinary-multipoint optimization system
developed at the von Kármán Institute and its applications to turbomachinery
design is presented. To speed up the convergence to the optimum
geometry, the method combines an Artificial Neural Network, a Design Of
Experiment technique and a Genetic Algorithm. The different components
are described, the main requirements are outlined and the basic method is
illustrated by the design of an axial turbine blade.
A procedure for multipoint optimization, aiming for optimal performance
at more than one operating point, is outlined and applied to the optimization
of a low solidity diffuser.
The extension to a multidisciplinary optimization, by combining a Navier-
Stokes solver with a Finite Element Analysis, allows an efficient search for
a compromise between the sometimes conflicting demands of high efficiency
and respect of mechanical constraints. It is shown that a significant reduction
of the stresses is possible with only a small penalty on the performance and
that this approach may lead to geometries that would normally be excluded
when using less sophisticated methods.
6.1 Introduction
Computational Fluid Dynamics (CFD) has seen a very important development
over the last 30 years. Navier-Stokes (NS) solvers have reached a high
level of reliability at affordable cost. They are now routinely used to ana-
René A. Van den Braembussche
von Kármán Institute for Fluid Dynamics,
Turbomachinery and Propulsion Department,
Waterloose steenweg, 72, 1640 Sint-Genesius-Rode, Belgium
(e-mail: vdb@vki.ac.be)
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