Axial-Gap Size Effect on the Unsteady Flow Field at Midspan in a 1.5-Stage Low-Pressure Turbine

verfasst von: Marcel Oettinger, Michael Henke, Florian Herbst, Jörg Reinhart Seume
Abstract: The unsteady pressure field at midspan in a 1.5-stage low-pressure turbine is analyzed for axial gaps equal to 20%, 50% and 80% of the stator axial chord. The stator blading is instrumented with unsteady pressure taps which are compared to numerical URANS calculations. The primary unsteady interaction mechanisms are the upstream stator and rotor wakes as well as the potential-field interaction between rows. As one might expect, the intensity of these effects generally diminishes with an increase in axial-gap size; some superposition effects do, however, counteract this trend. Due to the blade count ratio of the stators, the second stator row can be divided into blades strongly affected by the upstream stator wake and blades that are affected to a lesser degree. The blades more strongly affected show higher pressure amplitudes and higher order modes induced by wake-wake interaction. As a result of wake-wake interaction, the stator 1 wake inhibits the commonly observed negative-jet effect. This, in turn, affects the wake-blade interaction inside the passage and the resulting loss generation. Additionally, strong inter-dependency of wake and potential field interaction is observed. These superposition effects also modulate the loss generating mechanisms and their dependency on the axial-gap size.
Organisationseinheit(en): Institut für Turbomaschinen und Fluid-Dynamik
Typ: Aufsatz in Konferenzband
Publikationsdatum: 2019
Publikationsstatus: Veröffentlicht
Peer-reviewed: Ja

BibTeX

@inproceedings{838a23a3e21b4908a2f3020d858d7a9a,
title = "Axial-Gap Size Effect on the Unsteady Flow Field at Midspan in a 1.5-Stage Low-Pressure Turbine",
abstract = "The unsteady pressure field at midspan in a 1.5-stage low-pressure turbine is analyzed for axial gaps equal to 20%, 50% and 80% of the stator axial chord. The stator blading is instrumented with unsteady pressure taps which are compared to numerical URANS calculations. The primary unsteady interaction mechanisms are the upstream stator and rotor wakes as well as the potential-field interaction between rows. As one might expect, the intensity of these effects generally diminishes with an increase in axial-gap size; some superposition effects do, however, counteract this trend. Due to the blade count ratio of the stators, the second stator row can be divided into blades strongly affected by the upstream stator wake and blades that are affected to a lesser degree. The blades more strongly affected show higher pressure amplitudes and higher order modes induced by wake-wake interaction. As a result of wake-wake interaction, the stator 1 wake inhibits the commonly observed negative-jet effect. This, in turn, affects the wake-blade interaction inside the passage and the resulting loss generation. Additionally, strong inter-dependency of wake and potential field interaction is observed. These superposition effects also modulate the loss generating mechanisms and their dependency on the axial-gap size.",
author = "Marcel Oettinger and Michael Henke and Florian Herbst and Seume, {J{\"o}rg Reinhart}",
year = "2019",
language = "English",
booktitle = "Proceedings of the International Gas Turbine Congress (IGTC) 2019",
publisher = "Gas Turbine Society of Japan (GTSJ)",
address = "Japan",
note = "International Gas Turbine Congress (IGTC) 2019 ; Conference date: 17-11-2019 Through 22-11-2019",
}