Tandem compressor cascades are two similar blade rows behind one another. In contrast to single vanes the numerical and experimental investigations of tandem vanes show that these are able to perform greater turning and less losses. This makes them much more attractive to be used in highly loaded areas within the compressor. Though previous studies had been conducted mainly in 2D flows. Due to pressure gradients within the passage, high turning tandem vanes show massive areas of secondary flow near hub and casing. The strength and position of those secondary flows in the tandem passage are mainly depended on the load split between the front and the rear vane. Studies support the fact that a load split of 50% shows the best distribution. In this context it cannot be clarified which definition of load has to be used. This paper aims at answering the question whether the de Haller or diffusion number need to be utilized. Therefor, numerical and experimental investigations of a single and two tandem vanes with a turning of ∆β = 50◦ are being presented. A load split of LS = 50% is being applied to both tandem vanes. Each vane is being made up of an aspect ratio of AR = 1 which leads to high secondary flow effects. The experimental data is collected with in a subsonic compressor cascade with an inlet mach number of Ma = 0.6. In addition to that, numerical data is calculated. Therefore RANS calculations are performed using the Spalart Allmaras and the k − ω-SST EARSM turbulence model as well as the γ-ReΘ transition model. In order to compare the numerical and experimental data loss loops, radial profiles and streamlines are being shown. To identify the advantages of the tandem vanes a pure numerical investigation is performed by use of the Spalart Allmaras turbulence model. The results show that the tandem vanes are superior compared to the single vane. Moreover the tandem vane with a load split of 50% based on the de Haller number shows less secondary flow effects on the front vane because of a lower loading.
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Tandem compressor cascades are two similar blade rows behind one another. In contrast to single vanes the numerical and experimental investigations of tandem vanes show that these are able to perform greater turning and less losses. This makes them much more attractive to be used in highly loaded areas within the compressor. Though previous studies had been conducted mainly in 2D flows. Due to pressure gradients within the passage, high turning tandem vanes show massive areas of secondary flow...
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