F. Blaim, R. Niehuis

This paper gives an overview of the capabilities for unsteady flow simulations of low pressure turbine cascades by using modern transition models. The numerical results are compared to the experimental test case T106D-EIZ measured at the high-speed test facility of the University of German Armed Forces Munich. The T106D-EIZ is an ultra-high-lift profile with a pitch to chord ratio of 1.05 and therefore has a big separation bubble even at a high Reynolds number. Many transition models are calibrated with the moderately loaded (pitch to chord ratio of 0.799) T106A test case, which makes the T106D-EIZ a very demanding test case for the prediction capabilities of modern transition models using the Unsteady Reynolds Averaged Navier Stokes (URANS) equations. A special focus lies on the comparison between the different correlations proposed by Menter and Malan for the local quantities transport transition model. Both correlations are compared to the experimental results and results obtained by a transition model relying on integrated boundary layer parameters. In a first step the results of the steady test case situation are analysed to calibrate the correct axial velocity density ratio for the quasi 3D calculation. After that time averaged isentropic Mach number distributions, obtained by unsteady flow simulations, are analysed to highlight the differences between the different transition models. This also includes comparisons of time space distributions of the quasi wall shear stress rate with computed shear stress rate. Especially in that analysis larger differences were found, which could not be explained using the conventional time space diagram. Therefore, a 3D time space diagram was used to highlight the differences within the local quantities used by the transition model. This analysis lead to a proposal in which way this model could be improved to gain better prediction capabilities.

Deutscher Luft- und Raumfahrtkongress 2012, Berlin

Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn, 2013

Conference Paper

englisch

21,0 x 29,7 cm, 10 Seiten

urn:nbn:de:101:1-201301282239

Low-Pressure-Turbine, Transitionsmodellierung

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25.01.2013