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Reducing Secondary Flow Losses in Low-Pressure Turbines: The “Snaked” Blade

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Department of Industrial Engineering, University of Florence, Via S. Marta, 3, 50139 Florence, Italy
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Avio Aero, Viale I Maggio, 56, 10040 Rivalta di Torino, Torino, Italy
*
Author to whom correspondence should be addressed.
This paper is an extended version of the paper published in Proceedings of the European Turbomachinery Conference, ETC13, Lausanne, Switzerland, 8–12 April 2019; Paper No. 338.
Int. J. Turbomach. Propuls. Power 2019, 4(3), 28; https://doi.org/10.3390/ijtpp4030028
Received: 7 June 2019 / Revised: 17 July 2019 / Accepted: 5 August 2019 / Published: 21 August 2019
This paper presents an innovative design for reducing the impact of secondary flows on the aerodynamics of low-pressure turbine (LPT) stages. Starting from a state-of-the-art LPT stage, a local reshaping of the stator blade was introduced in the end-wall region in order to oppose the flow turning deviation. This resulted in an optimal stator shape, able to provide a more uniform exit flow angle. The detailed comparison between the baseline stator and the redesigned one allowed for pointing out that the rotor row performance increased thanks to the more uniform inlet flow, while the stator losses were not significantly affected. Moreover, it was possible to derive some design rules and to devise a general blade shape, named ‘snaked’, able to ensure such results. This generalization translated in an effective parametric description of the ‘snaked’ shape, in which few parameters are sufficient to describe the optimal shape modification starting from a conventional design. The “snaked” blade concept and its design have been patented by Avio Aero. The stator redesign was then applied to a whole LPT module in order to evaluate the potential benefit of the ‘snaked’ design on the overall turbine performance. Finally, the design was validated by means of an experimental campaign concerning the stator blade. The spanwise distributions of the flow angle and pressure loss coefficient at the stator exit proved the effectiveness of the redesign in providing a more uniform flow to the successive row, while preserving the original stator losses. View Full-Text
Keywords: secondary flow; LPT; blade redesign; “snaked” blade secondary flow; LPT; blade redesign; “snaked” blade
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Giovannini, M.; Rubechini, F.; Marconcini, M.; Arnone, A.; Bertini, F. Reducing Secondary Flow Losses in Low-Pressure Turbines: The “Snaked” Blade. Int. J. Turbomach. Propuls. Power 2019, 4, 28.

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