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Open AccessArticle

The Influence of Different Wake Profiles on Losses in a Low Pressure Turbine Cascade

1
Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, UK
2
Department of Mechanical Engineering, University of Melbourne, Melbourne 3010, Australia
*
Author to whom correspondence should be addressed.
This paper is an extended version of our paper published in Proceedings of the European Turbomachinery Conference ETC12 2017, Paper No. 213.
Int. J. Turbomach. Propuls. Power 2018, 3(2), 10; https://doi.org/10.3390/ijtpp3020010
Received: 14 December 2017 / Revised: 21 March 2018 / Accepted: 11 April 2018 / Published: 17 April 2018
Large eddy simulations were carried out in order to investigate the influence of unsteady incoming wakes with different profiles on the loss mechanisms of the high lift T106Alinear low-pressure turbine (LPT) cascade. Bars placed upstream of the LPT blade were set into rotation around their axis, thus generating circulation, as well as asymmetrical wake profiles. Three different rotation rates were simulated, yielding different wake parameters that were then compared to an actual turbine blade wake profile. Whereas the commonly-used non-rotating bars generated wakes with turbulent kinetic energy levels several times higher than that of an actual blade wake, the case with counter-clockwise rotation led to more rapid wake mixing. All three wakes were able to trigger boundary layer transition and thus intermittently prevent separation on the suction surface. However, the weaker the wakes, the larger and longer lasting the separation bubbles became, and an increase in profile losses could be observed. Interestingly, the configuration with the weakest wake and the largest separation bubble resulted in a reduction of the overall LPT loss. View Full-Text
Keywords: low-pressure turbine; wake boundary layer interaction; transition; incoming wakes; unsteady effects low-pressure turbine; wake boundary layer interaction; transition; incoming wakes; unsteady effects
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Hammer, F.; Sandham, N.D.; Sandberg, R.D. The Influence of Different Wake Profiles on Losses in a Low Pressure Turbine Cascade. Int. J. Turbomach. Propuls. Power 2018, 3, 10.

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