TY - JOUR

T1 - Loss assessment of the axial-gap size effect in a low-pressure turbine

AU - Oettinger, Marcel

AU - Mimic, Dajan

AU - Henke, Michael

AU - Schmunk, Oleg

AU - Seume, Joerg R.

N1 - Funding Information: MTU Aero Engines AG.

PY - 2021/1/26

Y1 - 2021/1/26

N2 - The aim of this work is the decomposition, quantification, and analysis of losses related to the axial-gap size effect in a 1.5-stage low-pressure turbine. Both experimental data and unsteady RANS calculations are investigated for axial gaps equal to 20%, 50% and 80% of the stator axial chord. A framework for identifying sources of loss typically encountered in turbomachinery is derived and utilized for the low-pressure turbine presented. The analysis focuses on the dependency between these losses and the axial-gap vari-ation. It is found that two-dimensional profile losses increase for smaller gaps due to higher wake-mixing losses and unsteady wake-blade interaction. Losses in the end-wall regions, however, decrease for smaller gaps. The total system efficiency can be described by a superposition of individual loss con-tributions, the optimum of which is found for the smallest gap investigated. It is concluded that these loss contributions are characteristic for the medium aspect-ratio airfoils and operating conditions investigated. This establishes a deeper physical understanding for future investigations into the axial-gap size effect and its interdependency with other design parameters.

AB - The aim of this work is the decomposition, quantification, and analysis of losses related to the axial-gap size effect in a 1.5-stage low-pressure turbine. Both experimental data and unsteady RANS calculations are investigated for axial gaps equal to 20%, 50% and 80% of the stator axial chord. A framework for identifying sources of loss typically encountered in turbomachinery is derived and utilized for the low-pressure turbine presented. The analysis focuses on the dependency between these losses and the axial-gap vari-ation. It is found that two-dimensional profile losses increase for smaller gaps due to higher wake-mixing losses and unsteady wake-blade interaction. Losses in the end-wall regions, however, decrease for smaller gaps. The total system efficiency can be described by a superposition of individual loss con-tributions, the optimum of which is found for the smallest gap investigated. It is concluded that these loss contributions are characteristic for the medium aspect-ratio airfoils and operating conditions investigated. This establishes a deeper physical understanding for future investigations into the axial-gap size effect and its interdependency with other design parameters.

KW - Axial gap

KW - Axial turbines

KW - CFD

KW - Loss breakdown

KW - Turbine efficiency

UR - http://www.scopus.com/inward/record.url?scp=85116783129&partnerID=8YFLogxK

U2 - 10.33737/jgpps/127834

DO - 10.33737/jgpps/127834

M3 - Article

AN - SCOPUS:85116783129

VL - 5

SP - 1

EP - 14

JO - Journal of the Global Power and Propulsion Society

JF - Journal of the Global Power and Propulsion Society

ER -