|Reference : Investigating Circumferential Non-Uniformities in Throughflow Calculations using an Harm...|
|Scientific congresses and symposiums : Paper published in a book|
|Engineering, computing & technology : Mechanical engineering|
Engineering, computing & technology : Aerospace & aeronautics engineering
|Investigating Circumferential Non-Uniformities in Throughflow Calculations using an Harmonic Reconstruction|
|Thomas, Jean-Philippe [Université de Liège - ULg > Département d'aérospatiale et mécanique > Turbomachines et propulsion aérospatiale >]|
|Léonard, Olivier [Université de Liège - ULg > Département d'aérospatiale et mécanique > Turbomachines et propulsion aérospatiale >]|
|Proceedings of the ASME Turbo Expo 2008|
|ASME Turbo Expo 2008: Power for Land, Sea and Air|
|du 9 juin 2008 au 13 juin 2008|
|[en] The ﬂow ﬁeld in a multistage turbomachine is very complex. It is 3D, unsteady and turbulent. Even if modern simulation tools can describe most of the ﬂow features, the computation time needed and the extraction of useful information remain severe drawbacks to systematic use of URANS codes in a design procedure. In this context the throughﬂow simulation proved to be more convenient. Nevertheless the need for empiricism limits the potential of throughﬂow solvers.
As an alternative, Admaczyck (1984) proposed three averaging operators (ensemble, time and passage) that lead to the average-passage model, linking the unsteady turbulent ﬂow ﬁeld to a steady ﬂow ﬁeld in a typical blade passage. This model involves additional terms that respectively bring back the mean effect of turbulence, deterministic unsteadiness and aperiodicity on the mean periodic ﬂow. These terms need to be modelled; it is the closure problem. Harmonic closure, which consists in solving a linearized perturbation system in the frequency domain, revealed to be an efficient method to approximate deterministic stresses (He and Ning, 1998, Stridh, 2005, Vilmin, 2006).
A fourth averaging can be performed, a circumferential averaging, giving rise to the throughﬂow model. Additional terms appear: the so-called circumferential stresses. It has been proven that these terms play an important role in the description of the ﬂow (Jennions, 1986, Perrin, 1995), being at least as considerable as deterministic stresses. Introducing these terms in a throughﬂow simulation allows to reproduce the averaged 3D steady ﬂow ﬁeld (Simon, 2007). The aim of the present contribution is to prove that harmonic method can potentially be used to reconstruct circumferential stresses.
The importance of circumferential stresses in a throughﬂow simulation is ﬁrst highlighted on a single stage low speed compressor testcase, for viscous and non-viscous ﬂow ﬁelds. The second step is the characterization of the frequency spectrum of the circumferential perturbation ﬁeld. Next are compared the stresses associated to a Fourier reconstruction of the perturbation ﬁeld with the real ones. Finally the approximated circumferential stresses are injected into a throughﬂow simulation tool to analyse and demonstrate their capability to reproduce a 3D averaged ﬂow ﬁeld.
|Researchers ; Professionals ; Students|
|ASME Paper GT2008-50328|
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