Investigating Circumferential Non-Uniformities in Throughflow Calculations Using an Harmonic Reconstruction

The computation time and the extraction of useful information remain severe drawbacks to systematic use of modern three-dimensional Navier-Stokes codes in a design procedure of multistage turbomachines. That explains why throughflow simulation is still widely used at industrial scale. The main limitation of throughflow is however the need for empirical models to reproduce blade-flow interactions and major 3D flow features. The purpose of this work is to investigate the degree to which empiricism could be reduced by using the averaged-passage equations of Adamczyk, combined with an harmonic closure strategy. To that aim, results of a computation performed with a steady three-dimensional Navier-Stokes code are used to calculate some of the additional terms of the circumferentially-averaged equations, the so-called circumferential stresses. The importance of the latter to bring back the mean effect of circumferential non-uniformities is proven by injecting them into a throughfow simulation. The frequency spectrum of these terms is next investigated and it is demonstrated that an harmonic reconstruction can model the circumferential stresses.Copyright © 2008 by ASME

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