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Research Papers

Blade–Row Interactions in a Low Pressure Turbine at Design and Strong Off-Design Operation

[+] Author and Article Information
Martin Lipfert

Institute of Aircraft Propulsion Systems,
Stuttgart University,
Pfaffenwaldring 6,
Stuttgart D-70569, Germany
e-mail: lipfert@ila.uni-stuttgart.de

Jan Habermann, Martin G. Rose, Stephan Staudacher

Institute of Aircraft Propulsion Systems,
Stuttgart University,
Pfaffenwaldring 6,
Stuttgart D-70569, Germany

Yavuz Guendogdu

MTU Aero Engines,
Dachauer Strasse 665,
Munich D-80995, Germany

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received June 30, 2014; final manuscript received July 10, 2014; published online August 26, 2014. Editor: Ronald Bunker.

J. Turbomach 136(11), 111002 (Aug 26, 2014) (10 pages) Paper No: TURBO-14-1102; doi: 10.1115/1.4028213 History: Received June 30, 2014; Revised July 10, 2014

In a joint project between the Institute of Aircraft Propulsion Systems (ILA) and MTU Aero Engines, a two-stage low pressure turbine is tested at design and strong off-design conditions. The experimental data taken in the Altitude Test Facility (ATF) aims to study the effect of positive and negative incidence of the second stator vane. A detailed insight and understanding of the blade row interactions at these regimes is sought. Steady and time-resolved pressure measurements on the airfoil as well as inlet and outlet hot-film traverses at identical Reynolds number are performed for the midspan streamline. The results are compared with unsteady multistage computational fluid dynamics (CFD) predictions. Simulations agree well with the experimental data and allow detailed insights in the time-resolved flow-field. Airfoil pressure field responses are found to increase with positive incidence whereas at negative incidence the magnitude remains unchanged. Different pressure to suction side (SS) phasing is observed for the studied regimes. The assessment of unsteady blade forces reveals that changes in unsteady lift are minor compared to changes in axial force components. These increase with increasing positive incidence. The wake-interactions are predominating the blade responses in all regimes. For the positive incidence conditions, vane 1 passage vortex fluid is involved in the midspan passage interaction, leading to a more distorted three-dimensional (3D) flow field.

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References

Figures

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Fig. 2

NGV2 midspan—incidence definition and Kulite-positions

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Fig. 1

Meridional view of the ATRD-rig annulus

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Fig. 5

Experimental results of unsteady lift coefficient distribution on NGV2 midspan streamline for all operating points. (a) Off-design i = +18 deg, (b) ADP, and (c) off-design i = −18 deg.

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Fig. 6

Numerically predicted results of unsteady lift coefficient distribution on NGV2 midspan streamline for all operating points. (a) Off-design i = +18 deg, (b) ADP, and (c) off-design i = −18 deg.

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Fig. 7

Range of NGV2 lift coefficient cp; lines indicate CFD-results; (solid line) average; (dashed–dotted) minimum; (dashed line) maximum. (a) Off-design i = +18 deg, (b) ADP, and (c) off-design i = −18 deg.

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Fig. 3

NGV2 midspan—lift distribution; lines indicate CFD-results; symbols mark the measured data

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Fig. 4

NGV2 Inlet—variation of incidence

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Fig. 8

NGV2 passage characteristics at positive incidence operation i = +18 deg; lines indicate wake fluid. (a) t/τR1=0.5, (b) t/τR1=0.75, and (c) t/τR1=0.85.

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Fig. 10

NGV2 outlet—variation of axial Mach number

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Fig. 9

NGV2 outlet—variation of turning

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Fig. 11

NGV2 midspan—unsteady lift

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Fig. 12

NGV2 midspan—unsteady axial thrust

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