Statistical Analysis of Parameter Variations Using the Taguchi Method

A. Wolf, D. Henes, S. Bogdanski, Th. Lutz, and E. Kramer

Abstract. This project is part of the MUNA-project. It deals with the investigations of uncertainties of a CFD-Simulation caused by variation of numerical parameters, inflow conditions and geometrical parameters. To evaluate the influence of different parameters on the results of an experiment or simulation usually a full parameter analysis must be performed. A full parameter analysis requires a high number of simulations, rising with the number of parameters, which are investigated. In this study the Taguchi method, which is based on DoE (Design of Experiments) meth­ods and well known for the optimization of production cycles, is applied. It reduces the number of required simulations dramatically and therefore also the costs. In this article the basics of the Taguchi Method are explained and a summary of the ANOVA-analysis, is given. The ANOVA analysis is used for the analysis of the results obtained by the Taguchi method. It delivers the relative influences of each investigated parameter and also the influence of interaction among different para­meters can be obtained. The effect of the parameter variations on the CFD result is shown for two – and three dimensional simulations. Numerical, geometrical and also inflow conditions are investigated.

1 Introduction

The aim of this project is to investigate the uncertainties in CFD-results if differ­ent numerical (i. e numerical diffusion) and geometrical (i. e. trailing edge thickness) parameters are varied. Most of the settings used for CFD simulations are based on experience and it is unknown how the result behaves if these parameters are

A. Wolf • D. Henes • S. Bogdanski • Th. Lutz • E. Kramer Institute of Aerodynamics and Gasdynamics, University of Stuttgart e-mail: wolf, lutz@iag. uni-stuttgart. de,

Pfaffenwaldring 21, 70569 Stuttgart

B. Eisfeld et al. (Eds.): Management & Minimisation of Uncert. & Errors, NNFM 122, pp. 247-264. DOI: 10.1007/978-3-642-36185-2_10 © Springer-Verlag Berlin Heidelberg 2013

changed. On the other hand there are also natural variations like fluctuating inflow conditions and production inaccuracies. Their effect is unknown as well. To eval­uate the influence of all these parameters, usually a full parameter analysis must be performed. As such an analysis requires several thousand simulations, the Tagu- chi method is introduced in this article, which requires a much lower number of simulations. The Taguchi method enables to investigate the relative influence of dif­ferent parameters on the CFD result by systematical variation of these parameters. It also enables to investigate the effect of the interactions between two parameters. It could be shown that in some cases the strongest influences on the CFD results stem from such interaction effects. In the first part of this article the Taguchi Method is explained and the results of the simulations are presented in the second part. The parameters are arranged in different groups depending whether they are numerical based, geometrical based or belong to inflow conditions. As test case the RAE2822 is chosen. The inflow conditions are taken from [1].