15th European Conference on Turbomachinery Fluid dynamics & Thermodynamics

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Main Topic:

Axial Compressors



Valentin Caries - Laboratoire de Mécanique des Fluides et d'Acoustique (LMFA), France; Safran Aircraft Engines, France
Christophe Montsarrat - KTH Royal Institute of Technology, Sweden; Safran Aircraft Engines, France
Jérôme Boudet - Laboratoire de Mécanique des Fluides et d'Acoustique (LMFA), France
Eric Lippinois - Safran Aircraft Engines, France


The complex flow developing from the clearance at the tip of a compressor blade influences the efficiency, the stability and the noise emission. More specifically, the circulation and the trajectory of the tip-leakage vortex (TLV) are key design features. Major benefits can be expected if these aspects are taken into account in the early phases of design, when a great variety of geometries are to be evaluated, through optimization procedures. This requires rapid prediction methods with a broad domain of validity. In the present work, a vortex lattice method has been developed and evaluated for the prediction of the TLV. The wall surfaces are discretized using singularities, whose intensities are calculated to satisfy the slip condition at the walls. First, the discretization requirements are assessed, for the blade and the casing. A grid refinement criterion is introduced, with respect to the tip gap size. Second, the periodicity condition is developed and assessed, and the Prandtl-Glauert correction is introduced to account for mild compressibility effects. Third, the benefits of an object-oriented implementation in Python are presented, and various acceleration techniques are evaluated for the construction of the matrix and the resolution of the linear system. The computation time is reduced to a few seconds, on a single computer core, allowing for extended parametric/optimization studies to be carried out. Finally, the approach is evaluated in comparison with results from the literature, focusing in particular to the influence of the tip gap size. The circulation of the TLV is directly provided by the vortex lattice method, while the trajectory requires an additional correlation from the literature.


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